Bovine Reproduction Flashcards by Bibi S

Why is heat detection important?

Detection is important as most dairy herds rely on achieving 1 calf per cow per year.
Loss of $100-$200 per heat missed.

Poor heat detection results in increased calving-conception intervals thus reducing productivity and genetic gain.

Inseminating cows at the wrong stages of the oestrus cycle results in reduced pregnancy rates. Thus increasing costs and decreasing reproductive performance.

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What is a definitive sign of oestrus?

Cow standing still whilst being mounted

Secondary signs:
- Attempting to mount other cows/mounting without standing/disoriented mounting
- Vulvar mucous discharge, vular swelling
- Sniffing, licking, rubbing, chin resting
–> Rubbed pin bones or base of tail
- Restlessness, aggressive behaviour.

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What are endocrine characteristics of oestrus?

Progesterone: Low
Progesterone comes down as the follicle gets bigger at the end of diestrus

Oestradiol: High
Follicles increasing in size producing more oestrogen

LH: High
High amount of oestrogen generates the LH surge. After this the oestrogen comes down.

FSH: Coincides with LH surge. LH surge at the start of oestrus

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What are some factors affecting oestrus behaviour?

Moving animals: Increases oestrous behaviour as more interaction between cows
Temperature: less frequent with extreme weather
Number of cows in heat simultaneously increases
Stress decreases LH surge
Lamenesses decreases mounting activity
Nutrition/milk production: Greater negative energy balance –> less intense oestrus
Type of house (Slippery housing decreases oestrus)
Breed (Bod indicus decreases, holstein increases)
Age (Older, less intense)
Time of day: Increases in the night
Overall health: Sick cows less likely to demonstrate behavioural signs

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What is silent heat?

The cow is in oestrus but does not show signs of standing to be mounted

Causes: Factors that affect oestrus having a negative effect on cow behaviour: Common with first ovulation post partum

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How can you evaluate heat detection?

Sensitivity: (Number of cows detected in oestrus)/(number of cows in oestrus) x 100

Positive predictive value (PPV): (Number of correct detections)/(No. of correct correct + false positive detections) x 100

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How to improve efficiency of heat detection/PPV?

Synchronise oestrus in significant problem
Suspicious cows placed with oestrus cows
Heat detection aids
Cow identification and record keeping
Observe cow behaviour
Nutrition and health optimise
Train staff for good heat detection skills

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What are some heat detection aids?

Tail paint: Highest sensitivity/PPV
Apply strip on base of tail, liquid is better than aerosols.
Disadvantage: Have to repeat every 5-7 days, repeat causes crusting making it harder to rub off in oestrus.
Marking crayons: Similar to tail paint
Dis: Labour intensive, difficult when cows are sheding
Rum Mounted devices.
Kamars: Capsules with red dye and plastic dome on top. When cow jumps on top, it pushes dye through the small capillary tube and stains the dome. If red: in heat.

High sensitivity in Bos Indicus herds.
Dis: Removed during AI, can be false due to rubbing on branches, expensive, glue can be messy to deal with

Oestrus Alerts: Top is scratched off when cows mount
Dis: Enviromental contamination, cost, hard with wet cows, needs warmth for glue to stick, wears with time and hard to interpret
Pedometers: Walking increases with oestrus: Neck or leg anchored
Dis: Cost, changes in distance walked can affect interpretation, false negatives/positives
Progesterone Concentration: Concentrations of progesterone in plasma/milk to determine when cows are likely to be in oestrus.
Dis: Costs, delay in result if sent to lab, multiple samples needed.
Hormone Detector Animals:
Cows or Steers
Surgically modified males: Vasectomy, epididymectomy, penile deviation, penile fixation.
Dis: Costs, hazards via bulls, libido decreased
Electrical resistance of mucous: Probe inserted in the vagina and electrical resistance is measured.
Lowest reading in cow coincides with oestrus
Dis: Labour intensive, multile reading required to detect changes

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What are submission Rates?

Evaluates oestrus detection efficiency.
Is the percentage of cows submitted for AI within a given period of time.

Check the rate of cows calved <6 weeks before start of mating OR > 4 years of age

Low rates: High proportion of non cycling cows or poor oestrus detection

High rates: High oestrus detection or low accuracy of heat detection.

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How can you assess submission rates to evaluate heat detection in a herd for split calving and year round calving?

Seasonal/split calving: 3 week submission rate for early calved
Mature cows on day 22 of mating
Cows most likely to be calving
Target: 86%

Year round: At least every 2 months measure for 80 day submission rate
Target: 73%

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Why is the synchronisation of oestrus important?

Acronym: CRAM BLOOE
Synchronise oestrus causes:
- Calving-conception interval decreased. Calve early so there is more time to recover before next heat.
- Replacement heifers increased
- AI. Facilitates AI: Improves genetic gain
- Management: Synchronises parturition and drying off, transition feeding and calving.
- Bull no: Decreases
- Lactation length: Increases
- Oestrous detection and labour decreases as it confines it a shorter period of time
- Oestrus detection improved. As large number in oestrus simultaneously
- ET facilitation (embryo transfer).

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What are the disadvantages of synchronisation?

Acronym: UC CHOAR
- Unrealistic owner expectations
- Cost
- Conception rates reduced in spontaneously ovulating cows
- Handling increased: 3-4 interventions before AI, hard in a beef herd.
- Organisation skills required: Know which cows are not pregnant, enough inseminators available for amount of cows
- Appropriate handling & facilities
- Requirements for optimal reproductive performance still apply e.g. breeding weight

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What are the characteristics of an ideal oestrous synchronisation treatment?

Acronym: ME PANE
- Minimum duration/manipulation. Few manipulations/interventions as possible.
- Economic and acceptable residue of tissue/milk
- Precise synchronisation in time of oestrus and ovulation
- Any stage in/out of cycle.
- Normal fertility at the regulated oestrus and normal return to oestrus.
- Eliminates detection of behavioural oestrus & allows fixed AI

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What are the physiological requirements for synchronising oestrus?

Sync a decline in plasma/exogenous progesterone
Sync follicular development
Sync pre-ovulatory LH surge/stimulus
Ovulate follicles at optimum stage
Ovulating follicles have normal fertility
Concentration of progesterone is normal following sync oestrus.

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What are some strategies for achieving synchronisation goals?

a) Start of treatment (Tx): Sync new wave emergence
- 1. Induction of Ovulation/Lutenisation: GnRH or hCG (Expensive)
MOA: LH surge and new CL forms (follicle > 10mm).
Wave emergence: 1-2 days
Dis: Ineffective on immature follicles
Adv: Timed AI< decrease behavioural oestrus thus decrease in pasture damage
- 2. Atresia of Dominant Follicles: Oestrogen (oestrodial benzoate) with Progesterone (CIDR/Cue-Mate).
MOA: Decrease FSH and LH support for existing growing follicles (atresia)–> allows for New wave via increased FSH at emergence.
Wave emergence: 3-4 days
Dis: Not for lactating dairy cows (oestrodial not allowed)

b) At the end of treatment: Synch decline in Progesterone/P4
Inject PGF2a
Remove exogenous source of P4

c) During Follicular Phase: Sync pre-ovulatory LH surge to induce ovulation
Purpose:
- Increase sync of ovulation
- Enable fixed-time of insemination
- Increased probability that ovulation occurs in animals at risk of no ovulation e.g. prepuberty, anoestrous
Steps:
–> Inject GnRH/hCG: When progesterone is low, inject oestrogen to increase GNRH and cause LH surge
LH surge: 24-35 hrs
Ovulation: 24-34 hrs
AI: 12-16 hrs
–> Oestradial benzoate:
LH surge: 20 hours, Ovulation: 40-60 hours, AI: Heifers - 48 hours, Cows - 56 hours
Cheaper then GnRH, enables time/detected AI.
Dis: Not for lactating, intense behaviour, ineffective with immature follicles
–> Oestradiol cypionate:
LH Surge: 50 hours
Ovulation: 48-80 ours
AI: 48-56 hours after
Dis: Same as benzoate
Adv: Can admin at time of P4 removal which lowers yarding
–> eCG:
MOA: Stimulates follicular development
LH surge: N/A. Ovulation: 67 hr
Dis: Increase twinning rate, cost, less reliable (indirectly induces), sync is less
Adv: Increase progesterone following ovulation, increased probability in undernourished/anoestrus cows

d) Ovulate oocute with optimal fertility
- Restrict duration of dominance to 4days by limiting length of P4 treatment (7-10 days).
Progesterone inhibits GnRH, if it is not high GnRH persists and have long dominance that effects fertility.

e) Optimimum concentration of P4 ost ovulation
Induce ovulation of follicles > 10mm (good maturity).
Admin eCG when CIDER/Cue-Mate/DIB removed
Do not want to force ovulate growing follicles.
Immature follicles: Low fertility –> Either no ovulation or low production of P4 (small CL)
If too Mature Follicles: Fertility declines
There is an optimum follicle age for inducing ovulation

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Describe in more detail the profile of LH after administration of oestradiol benzoate/oestradiol cypionate

After removing progesterone releasing insert given at the end of last treatment, you can administer benzoate 24 hours LATER.
There will be a rise in oestrogen and LH 24 hours later.
Then Inseminate
3 yardings: more intervention as you have to remove device, bring cows back after 24-48 hours to inject with benzoate, and then another 24 hours to inseminate them.
Need time to let follicle get bigger as the emerging follicle initially is too small –> Compromising pregnancy rates.

Cypionate on the other hand can be injected immediately after removing the progesterone releasing insert. However it takes 48 hours for the LH to rise. It takes longer to act
Adv: When you pull out the device you can give cypionate immediately and bring cows back 48 hours later to inseminate.
One less yarding than with benzoate

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What are PG Programs?

Aim is to synchronise decline in plasma concentrations of progesterone and initiate follicular phase

Administer intramuscular PGF2a or analogue (Cloprostenol), to cause luteolysis to sync P4 decline and follicular wave.
Cows: Day 7-18 of cycle.
Heifers: 5-18 days of cycle

One shot or two shot protocol:

2 injections, 12-14 days apart:
Ovulates day 3, by day 12: CL will be 10-11 days old. So give a second shot to ovulate again.
For Heifer: Ovulates by day 6.

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What are the advantages and disadvantages of PG programs?

Adv:
- Easy to administer IM injection
- Variety of programs to suit specific needs
- Fertility is normal
- Economical ($2-3 per injection)

Dis:
- Abortion in <5 months pregnant cows. Cows are accidentally injected.
- Health/Safety in humans: resp. difficulty, abortion
- Ineffective in anoestrus (non-cycling cows)
- Does not sync. follicular development so pattern of onset of oestrus is spread over 5-7 days.

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What is the progesterone or progestogen-based systems for synchronising oestrus in cattle?

Intravaginal, SC implants or Oral
Duration: 5-7 days
MOA: Acts as artificial CL, increases P4, removal causes decline of P4 –> Enter follicular phase
Can work on an oestrus cows, increase ovulation rates

Concurrent treatments:
- Luteolytic treatment is given to remove endogenous source of P4
- Post-sync of ovulation: GnRH/EB to sunchronise emergence of new follicular wave. Also synchronises ovulation at the end of treatment.

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How can you disinfect progesterone releasing devices

Autoclave
Submerge on removal and pressure hose
Soak in disinfectant
Dry and place in sealed container

Reuse only once – Depleted after 3 x

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How do animals with anoestrus benefit from treatment with progestogen?

Normally there is an increase in GnRH secretion to the point where the follicle can grow, develop and ovulate.
Progesterone device: First ovulation after induce: Increases chance for a normal post cycle treatment.

If anoestrus or pre pubital: There is a lot of oestradial receptors in the hypothalamus, sensitive to oestrogen. This can negatively feedback on GnRH and stop the animal from ovulating.
If you treat with PG: Decreases sensitivity of hypothalamus to oestradial, decreases the receptors. If remove progesterone, follicle starts producing oestrogen, and the hypothalamus is less sensitivie.
Instead of suppressed, it is stimulated.

Pre-treatment with progesterone increases the chance that pre-pubital/anoestrus animal will ovulate.
As the depth of anoestrus increases, it is harder to get animals to ovulate in response to oestrus synchronisation treatments.

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What is the adv/disadv of the GnRH program to synchronise oestrus

Adv:
- Simplicity
- Effective in non-cycling
- Intermediate cost
- Recommended if heat detection is a problem

Dis:
- 1st injection doesn’t always equate ovulation/lutenisation
- Low conception rates
- Decrease in cows showing heat proportionally
- Not recommended in heifers, as it can decrease pregnancy
- Prevents spontaneous ovulation (Decreases chance of responding to PG at end of treatment)
- No sync. of new wave
- high labour

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What is Ov-Synch?

It is a hybrid synchronisation of both GnRH and progesterone to increase response rates of first injection of GnRH.
Not always used due to increased cost and workload.
1. Inject GnRH (0 days –> Dominant follicule increases).
2. 7 days later inject PG (Luteolysis & new dominant follicule)
–> Prevents cows that do not responsd to GnRH from ovulating/entering oestrus.

9 days after this inject with GnRH again for ovulation of dominant follicle
Follicle ovulated 48 hours later.
TAI/insemination 16 hours after this

Others:
Co-Synch:
Inject GnRH at 0 days
PG at 7 days
Then at 9 days inject GNRH with insemination at the same time

Heat Sync: Oestradial not used in dairy cows anymore.
GnRH 0 days, PG 7 days then instead of GnRH at the 8-9 day mark, inject benzoate. Inseminate day 9-10.

Select Synch:
GnRH day 0, PG day 7.
Detect heat and AI. PG those who are not in heat.

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What are different techniques used in hybrid synchronisation protocol?

Pre-sync before ov-synch
Aim: Increase percentage of follicles that respond to the first GnRH injection of the OvSynch treatment.
Dis: Increase cost and handling
Different strategies for presynchrony:
a) Administer 2 x PG 14 days apart –> Ov-synch 12-14 days later
b) Inject PG and detect heat/AI for 3 days. Then start program with GnRH injection for non-inseminated cows
c) PG inejctions are followed by GnRH injection to increase chance of dominant follicle being present at start of an Ovsync
d) Double Ov Synch
Two injections of PG at end of ovsync treatment:
Timing:
a) 2 x PG 7 days after injecting GnRH either AM/PM or 1 day apart
b) Interval between 1st GnRH & PG can be decreased from 7 days to 5 days. Then 2 x 8-10 hours apart.
This can increase pregnancy rates following ov-synch, and increase proportion of cows with low progesterone at AI.
Beef Cattle
Aim: Reduce handling/yarding
Inject GnRH at same time of AI (60-66 horus post removal of CIDR/Cue-Mate)

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What are the indications for using OvSynch?

Poor heat detection
Not practicing continuous detection of heat
Simple reproductive program
Treatment of anoestrus.

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What is a CO-Sync and CIDR protocol?

Short-term protocols
Two types:
7 day CO-Synch + CIDR
GnRH day 0, PG day 7.
AI and GnRH at the same time day 9: Ones that aren’t in heat –> Ovulate with GnRH 24 hours later at the end

5 day CO-Sync + CIDR
Inject GnRH, 5 days later inject PG. Day 7 do AI and GnRH at the same time.
Heifers: follicle may be too small/luteolysis may not occur.
Give 2 injections of prostaglandin 24 hours apart to make sure luteolysis occurs.

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How can you resynchronise oestrus cycles?

Role: Synchronise return to oestrus after 1st or 2nd AI

Timing: Implemented following AI without knowledge of pregnancy status
Inseminate and synchronise those who did not get pregnant after the first insemination.
Pregnant ones are dropped out of the system

2 Strategies:
1. Resync without early preg testing:
Oestradial benzoate/EB: Relies on oestrus detection to ID those who need to be inseminated
W/o EB: CDRI, GnRH, PG: No visible oestrus to show, relies on TAI (AI)

Early Preg Testing & Resync
Allows non-pregnant cows to be ID’d and treated with PG
–> Insemination on detection or fixed (Or both)

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What is some important terminology with AI in cattle?

Conception Rate: (No. of inseminations with pregnancy x 100)/No. of Inseminations
Range: 30-60%
Pregnancy Rate: (No. of cows in herd selected that are pregnant x 100)/Total no. of cows selected
In-calf rate: Percentage of animals that are diagnosed as pregnant after a specific duration
E.g. 6 week in calf rate: The % of cows that are diagnosed as pregnant in first 6 weeks of the breeding period.

Non-Return date: Percentage of cows that are not detected in oestrus after insemination
Dis: Assumed to be pregnant (Imprecise)
Role: Positive correlation with conception rate,
Used by semen semen suppliers assess conception rates of different bull/AI Technicians where pregnancy data is not available.

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What are advantages and disadvantages fo AI?

Adv:
- Genetic Progress (Production increase) –> Genetic selection for desirable traits. EBV to select sires
- Disease control: Venereal diseases can be eliminated
- Wider sire choice
- Safety (bulls)
- Increased record keeping

Dis:
- Expensive (Beef > Dairy)
- Increased management for optimum condition of cows
- Decreased Repro performance in some circumstances e.g. poor quality semen/handling/technique/detection
- Skills required
- Increased undesirable traits (Dystocia)

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What are some AI equipments that are needed for insemination technique?

Equipment:
- AI guns & sheaths
- Semen (In straws)
- Lubricant
- Gloves
- Forceps, scissors
- Thawing container

Method: Wipe the vulva clean, enter insemination gun through the vulva and press arm down in the rectum to open the vulvar lips.
Follow progress of the gun with your hand in the rectum and work gum through the cervix.
Use index finger at the front of the cervix to feel the gun passing through. Do not want to progress too deep into the uterus. Only protruding from the front of the cervix.
Deposit semen slowly into the body of the uterus. (less chance of pregnancy in horn)
remove gun smoothly while arm is still inserted in the rectum.

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What is the method for semen collection?

Method: Artificial vagina (preferred), electroejaculation, artificial breeding mount (Steers > Cows)

Frequency: 3x per week total, up to 2x day

Amount: 4ml/ejaculate

Licensed: Free from physical defects and normal conformation
Must be free of: EBL (Enzootic bovine lucosis), IBR (Infectious bovine rhintoracheitis), Johne’s, tuberculosis, trichomonas, Lepto, BVDV, Q-Fever, Brucellosis, Ephemeral fever, Camplyobacteriosis

Unlicensed: Quality & Disease status not gurranteed

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How can you preserve semen?

Frozen semen: Most commonly used
1 step or 2 step method
2 step method:
Dilute semen in extender: Glucose, fractose, egg yolk, sodium chloride/citrate.
–> Stabilise cell membranes with no glycerol. Sit in fluid for several hours to cool to 4 degrees.
Then add glycerol fraction to the extender, cyroprotectant and helps the semen survive freezing.
Glycerol pushes water out of the cell, so there is no crystals of ice when frozen.
Then package into straws:
a) Vapour method: Straws 4cm abovet liquid nitrogen for 7-10 minutes. Then plunged into liquid nitrogen
b) Computerised freezing: Controlled freezing rate.
Straws transferred to liquid nitrogen tank for storage/distribution.

1 step: Same but Dilute in extender with glycerol initially. Better freeze with 2 step method.

Liquid semen: Semen is diluted in various liquid extenders and distributed for use. Dilute in caprogen extender.
Enables lower doses and maintains fertility for 72 hours.

Packaging:
- Plastic straws: 2 sizes –> 1/4mL of 1/2 mL
- Amploules/Pellets: No longer used for bovine semen

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What are some factors affecting pregnancy rates to AI?

Acronym: FP DIS SHT

Fertility of cows
Factors affecting cow fertility:
- Cycle status
- Calving to AI interval
- Milk-protein concentration
- BCS/Weight –> nutrition
- Stress
- Synchronisation of treatment & equipment (e.g. inaccurate dose)
- Breed
- Age/parity
- Disease, lameness
- suckling
Poor Records
- Insemination of incorrect cows, unable to assess performance + pregnancy loss during synchronisation treatment.
Dose
For optimum fertility: 5 to 10 x 10^6 live sperm per insemination required.
30% of sperm should be alive post thawing, with 30% of live sperm progressively motile at least.
–> There is an optimal dose with sperm and if it is below this it is less likely to cause pregnancy. Past the optimal dose the pregnancy rate plateaus, even though there is more sperm: No more pregnancy rate
–> Thus want to have the optimal dose.
Insemination Technique
Effects pregnancy rate due to technician error:
- Contaminated gun (faeces)
- Wrong location: not in body of the uterus
- Inseminating contralateral follicle to the preovulatory follicle
- Excess trauma to tract
- Poor thawing

Assess:
- Different technicians within the herd and analyse pregnancy rates achieved by diff technicians: At least 50 inseminations are needed for each technician to detect differences.

Storage
Sire
–> Sire effects due to: Variation in semen quality, longevity, ability to survive freezing and thawing & unknown factors
–> Straws from some bulls may require higher dose to compensate for lower fertility.
Handling/Thawing
Time between removal from nitrogen tank and AI: should be 15 minutes
Equipment/Site of thawing should be clean, dry, sheltered, warm
Thawing: Place in water bath 32-38 degrees for 30-50 seconds. Straws should be separated and dried with a paper towel.
Timing:
Timing of insemination post heat. 4-14 hours after the onset of oestrus is the ideal time.
Just below ovulation: Pregnancy rate is lower.
Too early: A lot of sperm die by the time the animal ovulates
Too late: Oocyte is waiting, oocyte fertility wanes as it is waiting too long for the sperm. Less quality.
- Ideally if oestrus onset is known, AI 4 to 14 hours post heat.

Issues:
- Unable to determine oestrus onset, unable to AI at optimum time (too many cows)
- If in heat/detected in oestrus: Inseminate as unknown what stage of oestrus cow is at
- If oestrus is detected infrequently, then Ai once daily.

AM-PM rule: Two stages of AI: AM oestrus –> PM insemination.
Recent work suggests that AI once daily is sufficient.

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What is Free-martinism and its pathogenesis?

Freemartinism is the sterile female of a male-female twin pair.

Pathogenesis:
- Vascular connections form between placenta of developing twins
- Co-mingling of blood supply –> Each Foetus becomes a Blood chimaera (both share blood cells/DNA)
*If prior to sexual differentiation (<Day 40), the female’s reproductive tract is affected by exposure to testosterone, anti-mullerian hormone and SRY gene.

AMH: Regressing of mullerian ducts –> Hypoplasia of cranial vagina, uterus, uterine tubes.
Testosterone: Varying degress of masculinisation: Large clitoris, increased anogenital distance.

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What are internal and external signs of free martinism? How can you diagnose?

External signs:
- Tuft of hair from ventral vulva labia, hypoplastic mammary teats resembling those seen in normal males
- Prominent clitoris
- Increase anogenital distance

Internal
- Short blind ending vagina: shorter in freemartin heifers than adults.
- Hypoplastic reproductive tract: Cervix absent, uterus hard to find, ovaries vary in size + sometimes seminal vesicles can be palpated.

Diagnose:
- PCR (EDTA): detection of Y alleles indicates blood sharing with male twin during gestation

Karyotyping: presence of Y Chromosome

Serum AMH: High levels of AMH expected in male/freemartin calves

Management: Cull at birth.

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What is Cystic Ovarian Disease?

Presence of an anovulatory follicular structure that persists on one or more ovaries.
> 2.5cm in diameter.

Hosts: 10% of dairy cows
Major cause of infertility and increased calving-conception rates

Pathogenesis: Inadequate LH surge via refractory nature to GnRH: Growth of anovulatory follicles.

–> Increasing oestradiol normally stimulates a GnRH surge thus stimulating a surge of LH from the pituitary, leading to ovulation.
A lack of responsiveness of the GnRH surge centre = inadequate preovulatory LH surge.

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What are the clinical signs and outcomes of Cystic Ovarian Disease?

CS:
- Anoestrous
- Nymphomania: Persistent oestrus
- Infertility
- Erratic oestrus
- Sterility hump: Chronic, relaxation of pelvic ligament due to increased oestrogen
Cows show frequent behavioural oestrus.

Outcomes:
1. Persist: For extended period (10-70 days) and remain dominant over other follicular structures

Turn-over: regress and replaced by a new follicular structure that forms a new cyst
Self-correction: Regress and replaced by a new ovulating follicular structure (20% of cows)

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How can you diagnose/treat for COD?

History of infertility/anoestrous
Palpation of follicle: > 2.5cm
Classification as a follicular cyst or luteal cyst
Behavioural signs

Treatment:
- No treatment: Spontaneous recovery
- Remove stressors
- Manual rupture/aspiration –> Risk of adhesions
- Induction of luteolysis if lutenisation has occured –> PGF2 alpha
- Induction of LH surge to induce ovulation/lutenisation
- Progesterone treatment to restore hypothalamic pituitary sensitivity to oestrodiol
- Combination therapy (OvSynch, P4 treatment + induction of ovulation)

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What are different types of cystic follicles?

Follicular
Path: Thin walled, P4 low, secrete oestradiol
–> Occurs post partum (15-45 days) transition from anoestrus to oestrus
Luteal
Thick walled, P4 high via lutenisation of thecal and granulosa cells, presence of CL
Dx: Difficult to differentiate via palpation, use ultrasonography.

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What is anoestrus?

Refers to the failure of cows to enter oestrus or to be detected in oestrous
10-30% may have a CL

Timing: Normal during early post partum
Most commonly 20 to 40 days.
–> Undernourished cows, cows that have higher genetic merit for milk production, higher incidence of retained foteal membranes/uterine discharge may take longer to resume cyclicity.

30 days after uterus is involuting, if the first cycle is missed: 2-3 cycles before the opportunity to get pregnant is missed.

Prevalence: 15-30% seasonal calving cows

Reduces repro performance, delays calving-conception, increased culling rate

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What are the types of anoestrous?

Anovulatory anoestrous: Absence of oestrous behaviour & failure to ovulate
–> CL is not present Ovaries are small

Ovulatory Anoestrus: Absence of oestrous behaviour but animal has ovulated.
–> 10-30% may have CL

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What are physiological changes assosciated with anoestrus?

GnRH & LH secretion are reduced during anoestrous via increased oestrogen receptors (Negative feedback)

If the animal is not physiologically ready for oestrus: The oestrogen produced by follicles feeds back to the hypothalamus oestrodiol receptors and suppresses GnRH
Ovary is functioning separately to the brain.

Closer to ovulation: Negative feed back sensitivity decreases. Greater ovarian stimulation, more oestradiol, decreased sensitivity of the hypothalamus –> eventually LH surge.

Other factors such as nutrition, suckling, metabolic factors interact with neurones that influence GnRH neurones, suppressing GnRH secretion.

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What is Ovarian Quiescence?

Cause of anoestrus in cows

Ovarian Quiescence
Principle cause: Negative energy balance
- Nutrition: Low BCS.
–> Nutritional deficiency: Deficiency of micronutrients e.g. P
- Nutritional excess prepartum: Over feeding

Lactation: Negative energy balance delaying cyclicity
Suckling: Neural effect to suppress GnRH secretion.
Physiological association between calf and cow.
Disease. Ovarian tumours, Cystic ovarian disease, abnormal gonad can cause
Age (pre-puberty)

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What are some other causes of anoestrus in cows?

Behavioural Anoestrus:
Silent Heat,
Nervous disposition, Extreme environment,
Housing (Slats, concretes),
Disease (lameness, ill)
Prolonged luteal function: Ovulated but progesterone remains high.
- Prolonged disorders
- Pyometra
- Pregnancy
- Early embryonic loss: Delay in return to oestrus
Failure to detect oestrus:
- Inadequate heat detection
- High production of milk
- Early postpartum

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How can you diagnose anoestrous in cows?

Monitor oestrus:
Over 3-4 weeks
Those not detected: Anoestrus/non-cycler

Can observe or use of aids for detection of oestrus: Tail paint, rump mounted, pressure activated devices

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What are some nutritional management strategies used for treating anoestrus in dairy/ beef cows?

Dairy:
- Optimise body condition score
- Optimise diet/transitional diet and dry matter intake
- Calve heifers before main herd begins calving to give them more time to recover before mating starts.
- Delay mating e.g. split calving/year round calving. To bring back their condition/recover.

Beef cows:
- Maximise nutrition
- Agistment/ supplementary feeding
Molasses/Dry licks. Source of protein/urea to maintain BCS.

Mineral supplementation: e.g. P during lactation
Spike feeding: Supplemental source of nutrition prior to calving/mating
Early weaning: Preserve condition and increase conception at next mating. Wean when cows condition score falls below 2.5.
Restrictive suckling: twice daily or prevent for 48 hours after removing CIDR/Cue-Mate

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How can genetic/heifer selection be used for treating anoestrus?

Select for shorter post partum anoestrus intervals
Select bulls based on EBV for fertility
Genotype for environment to reduce impact of environmental stressors
Select heifers with an earlier age of puberty, select heifers that got in calf earliest in the mating period.
Achieve critical mating/calving weights.

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What hormonal treatments for anoestrus?

P4 > 7 days: decreased sensitvity/receptors for oestrogen negative feedback. Thus increase in GnRH and decrease incidence of short cycles

High hypothalamic sensitivity to oestrogen occurs with an increase expression of oestradiol receptors in the hypothalamus.
Treatment with P4 devices, decreases the expression of these oestradial receptors, thus reducing the sensitivity of the hypothalamus to oestrogen negative feedback, allowing for increased secretion of GnRH.

PG: Not required post P4 removal if in anovulatory anoestrus, as they will not have a functional CL.
eCG: At the end of a P4 treatment can improve pregnancy rates
Ov-Synch: If initial GnRH injection does not work but no P4 pre-treatment
Biostimulation: Exposure to bull may reduce post-partum anoestrus interval.

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What is the effect of calving interval on conception rate?

The interval between calving and breeding has significant effect on pregnancy rate

Optimal: 60-80 days following calving to conceive.
Need to give cows enough rest at start of breeding season before mating.
Due to: Negative energy balance
Later calving and shorter calving to breeding intervals are associated with reduced fertility.

Optimise calving to breeding interval:
- Sync oestrus
- Selective culling/replacement of late cows
- Late calving bred later in the year alternatively. Split-calving dairy herds for cows that fail to conceive within a restricted mating period.

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What is a voluntary waiting period?

Time after calving during which no insemination occurs even if in heat.
30-60 days with 40-50 days best for most herds.

Short period < 30 days:
- Lower conception rate, only minimal extra pregnancies
- increase in 100 day in calf rate but lower 200 day not in calf rate
–> More opportunities to get pregnant.
- Increased semen use/cost

Long Period > 60 days
- Higher conception rates
- Reduced semen use
- reduce 100 day in calf rate and increase 200 day not in calf rate
More pregnant at the end of the breeding period.
–> Unnecessary delay in becoming pregnant
Increasing the average days in milk for the herd.

*high producing cows: Can afford for them to take longer to get pregnant. Greater lactation persistence may enable longer VWP.
Lower producing herd: Shorter VWPs

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What is the effect of heat detection on reproductive performance?

Improved detection = increase no. of cows submitted for AI & pregnant
within 6 weeks at the start of mating increasing

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What are the effects of body condition score post-calving?

Significant loss of BCS can reduce reproductive performance
- Increase intervals from calving to first ovulation
- Decrease conception rates
- Increase embryonic loss rates
- Produce less milk

Likelihood of Pregnancy at Day 40:
Loss of BCS: 25%
Maintained BCS: 38%
Gained BCS: 84%

Optimal BCS targets for dairy cows:
1-8 scale
At calving:
< 15% of cows below 4.5
< 15% of cows above 5.5

At mating:
Average decrease <0.6
<15% of cows lose >1 BCS since calving
Maintain or gain BCS from the start of mating

At drying off:
Herd average BCS 4.5-5.5
< 15% of cows below BCS 4.5

Optimal BCS - Beef:

Calving > 3
Mating: > 2.5, rising plane

DAIRY COWS:
TOO THIN:
- produce less milk
- longer post partum anoestrus
- less likely to get pregnant

TOO FAT:
- Reduced feed intake
- Don’t produce more milk
- Increased metabolic problems

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What are the targets for heifer liveweight and growth/its importance?

Heifer liveweight effects:
- Reproductive performance of maiden heifers/first calf heifers
- Lifetime milk production
- Calve easier and stay in herd longer

Target body weights at calving:
- Hostein-Freisian: calve heifers at 85% of their adult mature liveweight
- Jersey: 83%

Need to grow at the correct weight and speed = increased calving rate

Target bodyweights for heifers at mating:
- British breeds: 65% of adult mature weight
Dairy heifers: 55% of adult LW at time of mating
Bos indicus & continental breeds: 70% of adult mature weight

Critical Mating Weights - Beef:
Defined as weight at which 85% of heifers fall pregnant over 45 days. This is the weight at puberty as it reflects the weight at which most heifers for a breed will be cycling, and have high chance of pregnancy.
Achieve:
- Weigh regularly post-wean
- Supplementary feed to attain grwoth targets
- Parasite control at weaning and drench again 3-4 weeks prior to joining
- Ensure heifers are cycling in unison before mating.
- Maximise no. of heifers at critical mating weight 2-3 cycles before joining.

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What are the implications of variation in onset of puberty?

Weight at puberty varies between individual animals so selection of earlier onset is okay.
–> more chance to recover before calving
–> more cows get pregnant earlier
–> Try to control age of puberty to get more animals cycling by breeding time

Variation Reduced by:
- Controlling birth month
- Shortening duration of mating
- Supplementary feed for prepuberty heifers
- Breeding selection

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What are some management strategies to improve reproductive performance in beef heifers?

Aim for heifers to reach critical mating weight at the start of joining
Mate more heifers than will needed to allow good selection from pregnant animals. Mate 25% excess
Include lighter weighing heifers when mating –> early maturing animals
Preg tet –> Select all heifers that got in calf earliest in the mating period
Select on foetal aging and temperament.
Avoid excess hybrid vigour –> produce calf that is too big for the heifer –> Dystocia

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What is reproductive tract scoring?

It is assigned in heifers 6-8 weeks prior to mating to assess no. of heifers likely pubertal/cycling

Reproductive tract scores are from 1-5.
RTS score of 1 = infantile reproductive tract
RTS score of 5 = Pubertal, CL preset

Normal: >50% to have a reproductive tract score (RTS) of 4/5
Adv: Preg. rates increase with high RTS
Dis: Labour and skill required to assess bodyweight.

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What are the effects of genetics on fertility for Dairy cows?

ABV: Dairy (australian breeding value for dairy cows)
As ABV increases, genetic merit increased fertility.

Sires ABV rated based on the fertility of their daughters
1. Daughter Fertility ABV: Calculated by measuring the repro. performance of each sires daughters.
The Daughter Fertility ABV average is 100.
Cows with 100 ABV: Industry average 6 week in-calf rate.
Cows with 105: 6 week in calf rate 5% above the current industry average.
103: 3% greater than average for fertility.

Calving Ease ABV: Average is 100. Bulls with Calving Ease ABV above 100 have fewer assisted calvings than bulls that are below ABV.
–> Manage nutrition as well to manage calving ease.
Gestation length ABV: Indication of a bull’s influence on the number of days from conception to bird.
Average is 0.
To reduce gestation length, select bulls with gestation length ABV of less than 0.

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What is a balanced genetic portfolio? What about cross-breeding?

Instead of selecting for individual traits, you can select for indices that weight multiple different traits.
To make a balanced selection decision

BPI: Balanced performance Index
For:
- Production, health

HWI: Health Weighted Index
For:
- Fertility, mastitis resistance, feed saved, longevity

TWI: Type Weighted Index
For: Overall type and mammary system

*Selecting for High daughter fertility ABV + High BPI sires can positively influence herd fertility

Cross-breeding:
- Can improve fertility/
Holstein herds are more susceptible to inbreeding, negative effect on fertility over time/

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What are the effects of genetics on fertility for Beef Cows?

Days to Calving EBVs: Estimates genetic differences of fertility. Expressed as number of days from the start of the joining period until subsequent calving.
Lower days to calving EBV is more favourable, as quicker return to oestrus after calving and early conception.
Avg = 0, Select for < 0
Scortal Size EBV’s.
- Estimate of scrotal circumference at 400 days of age.
Larger scrotal size EBV more favourable: earlier age of puberty in heifers. Also have favourable relationship with days to calving. Bulls with larger Scrotal Size have daughters with shorter days to calving.

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What are the effects of herd age structure on fertility?

Insufficient replacement heifers and inadequate culling of aged cows can increase number of sub fertile cows in a herd. These are carry over cows

Carry over cows: Reduce repro. performance & milk yield. Fail to conceive, are heavier condition and low milk yield

Cull cows: > 10 year beef cows, 1st calf heifers that fail to produce in the 1st year, sub-fertile cows.

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How can bull management and power effect fertility?

Bull management
- Bulls should BSE tested, vaccinated for vibriosis, negative for BVDV, not used on other farms to prevent venereal diseases, not overfed
Parasite control
Adquate BCS, target weights
Select bulls with appropriate EBVs/ABVs, low risk of dystocia

Bull Power: Aim for 2.5-4% bulls per 100 cows
1 bull/30 heifers
When synchronising oestrus without AI: Increase bull power
Dairy herds: bull power can be based on how many pregnant in a herd.

*Maximum 2 bulls/100 cows for intensively managed southern herds
Maximum 4 bulls/100 cows for extensive grazing
Minimum 2 bulls/100 cows or per herd.

avoid single sire mating as if the bull fails it may be too late when realised. Increased risk of reduced calving %

Describe the duration of mating in Southern Beef Cattle

Southern Beef

Short Breeding Period of 9 weeks is Ideal.
Goals: 65-70% of calves born in the first 3 weeks,
20% in second 3 weeks,
10% in the third 3 weeks

To achieve ideal calving distribution:
- Maximum 60 days for bulls to run with cows (3 cycles)
Min: 45 days

Correction required: when > 20% cows conceive in the third oestrus cycle.

Longer Breeding Period (12-15 weeks)
Dis:
- Hard to maintain 365d ay calving interval
- Hard to achieve critical mating weight at nominated mating date for heifers that conceive later
- Wider spread of calf weights delays weaning & issues with calf marking and husbandry procedures
- Unnecessary Increase of high quality pasture and decrease availability for growing stock
- Increased Heifer culling and disrupted herd age structure
- Increased cost of supervision for calving heifers

Adv: Decreases NICR (Not in calf rate)

Split Calving:
Goals: 1st Cycle (3 week): 51-61%
2nd cycle: 77-94%
3rd cycle: 94-100%

Describe the time of calving in northern beef herds

Northern Beef: Green Date

Timing: Calve 6 weeks before reliable chance of seasonal break in beef herds to match available feed with increasing age.
- Usually after the green date

The green date is the number of days after the 1st October to achieve a 70% chance of receiving 50 mms of rain over a 3 day period.
Adv: Calving in Dec-Jan had the highest % of pregnancy <4m

*Calving earlier than the green date enables good quality feed to be available for calves when they are older and matches a cows nutrients demand.

Describe the autumn/spring calving in the Southern Beef Production Systems

Autumn Calving:
Calve: Late Feb
–> Calve before April as it will rain: moisture + Grass will grow. Increase in feed availability and good quality pasture
Mate: Late April
Wean: Mid July –> Pasture curve in August

Spring Calving
Calve: Aug
Starting to warm and get growth
Mate: Late Sep
Wean: Late Dec –> Miss Pasture Curve -> requires silage

What are the mating systems for beef cattle herds?

Seasonal or controlled mating
Segregated breeder management
Continuous mating (joining)

What is Seasonal/Controlled mating?

Only allowed to breed during selected weeks/months of the year to control pregnancy/calving

Adv:
- Supplementation reduced due to few/no dry season lactations
- Lactation matched with best pastures available
- Critical mating weight improved
- Selection of bull/heifer increased opportunities
- Preg diagnosis for early/late calvers
- Even weaner mix. Targeted weaner management
- Mustering reduced as fewer weaning rounds
- Reduced calf loss (no mustering during calving)

Dis:
- Risk of suboptimal pasture availability when mating commences. Variable and harsh conditions of N. Aus.
- Must segregate stock & control bulls.
- If poor bull control, must foetal age & remove late calvers
- > 70% mature breeders within 12 month inter-calving interval required for controlled mating to be successful

Described the continuous and segregated mating system in Northern beef

Continuous: Spread calving throughout the year, usually in extensive North Aus pastures with lock stocking rates
Adv: More calves are born
Dis: Spread of calving is wider

Segregated
Animals are grouped based on stage of gestation and body condition to allow personal intervention.
E.g. Maiden heifers, 1st calvers, mature cows
Gestation (<5m,5m)

Adv: Expenditure is where need, Avoid high mortalities

What are some factors that have been identified to significantly affect reproductive performance in beef herds in Northern Australia?

Regional effects on reproduction
BCS at Pregnancy diagnosis muster
P deficiency
Time of previous calving period
Seasonal pasture quality
Seasonal environmental conditions
Mustering within 2 months of calving/incomplete musters
Cow hip height
Cow age: 1st lactation vs older cows
Cow reproductive history: Cows that did not lactate in previous year
Presence of infectious diseases: Vibriosis, pestivirus, wild dogs.

What are some causes of declining milk fertility in dairy cows?

Effects of High Milk Production:
- Decreased repro performance
- Increase number of service/conception
- Increased calving-conception internval
- Decreased duration of heat

Cause of declining fertility
- Decrease Oocyte viability
- Reduction in fertilisation rates
- Less favourable environment for early embryonic development
- Lower concentrations of some repro. hormones e.g. P4
- Reduced embryonic growth rates
- Increase in early embryonic loss
- Placental insufficiency
- Increase in interoestrus intervals, delayed return to oestrus after AI of some cows (phantom cows)

Increase in dry matter intake and increase in metabolic rate
Increase in negative energy balance
Increase in concentrate feeding
Higher prevalence of anoestrus cows and longer post partrum to first ovulation intervals.

What are phantom cows?

Phantom cows are cows that are inseminated but fail to return to oestrus within 24 days of AI. But are diagnosed as non-pregnant.
Due to early embryonic loss.

What are some prevention strategies to minimise/reduce declining fertility?

Genetics
- ABV: Daughter fertility. Slow progress in preventing and heritability is low.
- Cross breeding: may reduce milk yield.
Nutrition
- Optimise BCS, reduce loss during lactation
- Decrease depth/duration of negative energy balance
- Maximise dry matter intakes
- Optimise transition period: Well balanced diet
Heat Detection
- Improve practices or consider fixed time AI to bypass detection
Health and Welfare
- Decrease dystocia
- Hygienic calving
- Manage uterine infections
- Optimise neonatal health
- Optimise nutrition/stress

What are the effects of heat stress on reproductive performance?

The thermoneutral zone: 23-27 degrees
Above this temperature the body actively regulates
Cows need to offload excess heat, cows ability to lose heat decreases as temperature increases

Increase in internal core temperature has effects on physiological processes, rumen function and oocyte quality/embryo viability

Dairy cows: More susceptible due to high feed intake and milk production

Heat Load: Heat produced internally by metabolic processes + Heat gained from the external environment - heat lost to the external enviro

Heat Loss:
a) at 30 degrees: Radiation, convection, conduction
b) at 40 degrees: Breath & Sweat evaporation

Humidity Thresholds:
- Stress: 68-71%
- Mild-moderate: 72-79%
- Moderate-Severe: 80-89
Severe: 90-99

What are the consequences of heat stress?

Fertility
- 6 week/100 day in calf rates decrease
- Not in calf rates increased
- Length and intensity of heats decreased
- Conception rates decreased
- Risk of embryo death increased
- Calf birth weight and viability reduced
Feed Intake/Nutrition
- 20-30% more maintenance energy needed to compensate for effort to keep cool
- Decreased Dry matter intake by 10-20%
- Decreased rumination/cud chewing
- Decreased ability to digest/absorb
Milk Production
- Drop by 10-25%, 40% in extreme
- Milk protein percentage decreased by 0.2-0.4%
- Milk fat percentage is more variable, severely decreased with ruminal acidosis
- Increase risk of mastitis due to increase SCC/Sediments in milk.
Cow Health:
- Decreased rumen buffering, decreased saliva
- Decrease Rumen pH
- Increased Ruminal acidosis/ketosis
- Risk of laminitis increased
- Immunosuprresion
- Risk of mastitis increased

How can you minimise the negative consequences of heat stress on fertility?

Breed heifers in warm months, less prone to heat stress.
Fixed time AI if detection is poor
Cool down cows
Cheaper semen in heat as pregnancy rates will be lower
Heat detection improved
AI to reduce infertility
Nutrition optimised
Genetic improvement: Tropically adapted, thermotolerant breeds
ET Transfer

What are the effects of nutrition on reproduction?

Undernutrition:
- Delays onset of puberty = Decrease in percentage of Heifers cycling at mating
- Delay first ovulation post calving, decreases pregnancy rates
- BCS loss due to early lactation
- Delayed uterine involution
- Increased embryonic loss
- Decrease concentrations of IGF-I: IGF-I increases the effects of LH on ovary. Thus low IGF-I reduces the effectiveness of LH
Dietary Protein:
- Rumen degradable nitrogen diets: Higher plasma concentrations ofblood urea nitrogen: Decrease conception rates, and change uterine pH, Increase intrauterine concentrations and alter hormone concentrations
- High protein: Variable: dairy based cows have superior conception.
- Avoid: Excess protein in mixed rations, sudden changes of protein during breeding.

Dietary imbalance: Reduced fiber –> Alteration in rumen function –> Reduce rumen pH –> Reduce fertility

Vitamins and Minerals
Involved in repro: P, Se/Vit. E. Cu, Mn, Co, Vit. A, Zn

Deficiency:
- Decreased activity of rumen micro-organisms and decreased digestibility
- Decreased integrity of reproductive cells –> Anti-oxidant effects
- Altered enzymes: Alters energy, protein and hormone synthesis
- Decreased conception
- Increased embryonic loss/abortion
- Increased post portum anoestrous intervals
- Decreased dry matter intake or digestibility
- Retained placental
- Increased perinatal mortalities

What are the mechanisms of abortion?

Disruption of normal endocrinology of pregnancy
Foetal death or stress

What are the factors induction abortion?

Maternal Illness e.g. Hypoxia, Endotoxemia, High Fever
Placentitis
- Release of PGF2 alpha, foetal death, foetal stress: Premature delivery.

Effects on foetus depends on:
- Organism
- Maternal Immunity
- Placental pathology
- Time of infection

What are the clinical manifestations of placental/foetal infection?

First trimester:
- Early embryonic death
- Regular or irregular return to oestrus
- Apparent infertility, abortion

Second trimester:
- Abortion, mummification, prolonged gestation, retained placenta

Third Trimester:
- Abortion, mummification, stillbirth, weak neonates, autolysed foetus, dystocia, retained placenta, serologically positive foetus

What BHV1

This is Bovine Herpes -1/Infectious Bovine Rhinotracheitis virus.

Subtypes:
- BHV-1.2 a causes abortions.
- BHV -1.2b is less pathogenic and does not cause abortion

Transmission: Direct contact with URT, conjunctiva or genital mucous membranes
Latency: Persistent carriers

Clincial signs:
- Abortion (> 5 months. Can occur 2-3 weeks post infection)
- Temporarily infertility
- Balanosposthitis (inflam of glans penis + prepuce)
- Enteritis
- Encephalitis
- Respiratory disease
- Infectious pustular vulvovaginitis

Diagnose:L
- FAT
- Virus isolation
- Serology (Poor)
- Histopathology: Multifocal necrosis with intranuclear inclusions

Control:
- Natural exposure
- Vaccination: Not available for BHV 1.2a
- Safe semen
- Biosecurity
- Eradication

What is Bovine Viral Diarrhoea Virus?

Transmission: Inhalation, ingestion, transplacental, venereal

Depends on:
- Viral strain and stage of gestation infection

Signs:
- Reduced repro performance
- Increased calf morbidity & mortality
- Decreased weaner/yearling growth rates/health.
- Mucosal disease
- Increased respiratory & diarrhoea in calves

How can you diagnose for bovine viral diarrhoea virus?

Tests on foetus: Retest for positive viral A tests to rule out transient infection
Tests on foetus:
- ELISA (Ag)
- BVDV ab (Pericardial fluid)
- Virus isolation or PCR
- Developmental defects
- Histopathology: Lesions in organs characterised by mononuclear cell infiltration & lesions of skin, lymphoid, cerebellar, ocular.

Tests on Herd:
Persistently Infected (PI) animals have a nil/weak Ab reaction but positive for Ag.

Sample Size: 8-12 animals from varied ae groups OR 5% of larger groups
- PCR:
- Virus Isolation
- Antibody ELISA: Ear notch -> take sample from the front of the ear. Colostrum Ab doesn’t interfere, retest PI 3 weeks later to confirm.
- Immunohistochemistry
- Viral Neutralisation teset
- Bulk Milk Testing: Tests for change or outbreak of seroprevalence via sample.
*The higher the sample to positive ratio (S/P), the more antibodies are present in the bulk sample. Thus higher the prevalence of seropositive cows in the herd.
S/P >1: Active/recurrent PI exposure
S/P > 0.75-1.0: relatively recent exposure
S/P: 0.25-0.75: Random/historic exposure
S/P: <0.25: naive herd, likely BVDV free
- AGID: Indication of seroprevalence and if infection is recent
- +1 - +2: Exposed to BVDV > 12 months ago
- > + 3: Recent infection, last 3-9 months
False neg: PI’s, Post-vaccination

How can you control an outbreak/introduction of BVDV?

Vaccination: Not useful in peak as foetal loss is 10-27 days PI with abortion at <50 days after
2x doses

To control sources of introduction investigate:
- Determine % of the herd at risk (Serology)
- Assess risk of exposure
- Autovaccination
- Remove PI’s
- Biosecurity

Control of Introduction:
1. Minimise risk of introduction
- Closed herd
- Test and quarantine all introduced cattle
- Vaccinate travelling cattle
- Avoid over fence contact

Minimise virus transmission
- Avoid mixing cattle
- Detect and remove PI’s
- Reduce BVDV transfer via fomites
Utilise AI:
- Registered semen/embryos
- Use BVDV-free media
- Test ET donors/recipients

What is Blue tongue Virus?

Transmission:
- Via bites from culicoides
- Contaminated semen
Strains: Aus strains cause little disease
Clinical signs:
- Cattle: no CS
- Sheep: Only naive show CS
- Early: Resorption, mummification, abortion
Infection 75-100 days: Still born, cerebral malformation

What is Akabane virus?

Source: Culicoides
Introduced via:
- Movement of naive cattle to endemic
- Movement of vectors
- Prolonged drought: Wet conditions favours the vector and naive cows infected
CS:
- Abortion, still births
- 76-104 days: Hydrocephaly
- 105-174 days: Arthrogryposis
- Dystocia

Diagnose:
- History
- Histopathology

Control: Vaccination & natural exposure

What is Brucellosis?

Bacterial cause of abortion
Most common in 2nd half of gestation
Route: Ingestion, AI, venereal, contaminated milk machines

CS:
Cows: Abortion: 2nd half of gestation. Stillbirths, weak calves, retained placenta, metritis
Bulls: Orchitis, epididymitis, seminal vesiculitis
Pathology: Chronic placentitis: Cotyledons and intercotyledonary areas affected

Diagnosis:
- Culture: Abomasal fluid, foetal lung, placenta, milk, uterine fluids
Serology: Rose-Bengal test, CFT, SAT

Control:
*Vaccination:
1. Strain 19: Live vaccine, persistent titres.
Vax heifers at 3-6 months
- RB-51: RB-51, Live vaccine no persistent titres. Vax heifers at 4-12 mths.

Control movement
Quarantined infected
Regular test and slaughter
Ring test (bull milk)
Repeated blood sampling

What is Listeriosis?

Cause: Poorly fermented silage
CS:
- Sporadic abortion in 3rd trimester
- Retained placenta
- Autolysed foetus
- Asymptomatic OR metritis and fever.

Diagnosis:
- Pinpoint white to yellow foci may be present in the liver
- Culture gram stain (Gram positive coccobacilli)
- Immunohistochemistry

Treatment and prevention:
- Dam: Systemic antibiotics (Penicillin)
- Avoid feeding poor quality feed

What is Leptospirosis?

Strains: Most common in cow - L. Hardjo, L. pomona, L. grippotyphosa

Transmission: Contact with MM/Skin

CS:
- Late term abortions or at any stage
- Systemic signs: Pyrexia, haemolytic anaemia, mastitis, hepatorenal disease, photosensitisation

Diagnose:
- Dark field microscopy
- FAT
- PCR: Urine
- Serology: Herd test
- Histopathology: Silver stains
- Culture; urine –> hard

TreatmentL
- Antibiotics: Oxytetracycline, ceftifur, tilmicosin, penicillin, amoxicilin
Control: Vaccination

What is Camplyobacter Fetus subsp. venerealis and tritrichomonas foetus

Transmission: Venereal, contaminated sperm, AI equipment
Hosts:
1. Males: asymptomatic carriers
2. Females: Immune following infection

CS:
- History of outside exposure
- Irregular return to oestrus
- Increased calving conception intervals
- Low fertility
- Long oestrus intervals
- Abortion: 4-7 months

Diagnose:
- Preputial wash/scare.
- PCR 3 x 1 week apart
- Vaginal mucous: Culture (Early in infection), ELISA
- Aborted foetal samples
- Virgin heifer test mating

Control:
- Vaccination
- Breeding: AI rather than nature breeding
- Segregate: By repro. status: Not pregnant, < 5 mths, > 5mths
- Avoid borrowed or stray bulls
Treatment: Vaccination, Oxytetracycline, Erythromycin, Dihydrostreptomycin

What is tritrichomonas foetus/trichomoniasis?

Protozoal cause of abortion.
Transmission: Venereal, contaminated sperm, AI equipment
Hosts:
1. Males: Asymptomatic carriers
2. Females: immune following infection <15 months

CS:
- History of outside exposure
- Increased calving conception intervals
- Long oestrus intervals
- Irregular return to oestrus
- Post coital pyometra
- Infertility from early embryonic death
- Abortion <5 months occasionally

Diagnose:
- Preputial wash/scrape: PCR: 3x tests- 1 week apart
- Vaginal mucus: Wet prep & culture
- Aborted foetal samples
- Virgin heifer test mating - IFT

Control:
- AI-
- Segregation! Not pregnant, <5m, >5m, aborted (cull?)
- Closed herd
- Test & cull positives
- Virgin bulls
- Avoid borrowed or stay bulls - ↓ length of breed season
- Only breed <5yr bulls

Treatment: No approved therapy & vaccine poor.
Nitroimidazole off-label
- cull

What is Neospora Caninum?

Transmission: Ingestion of sporulated oocysts, intra-uterine infection

CS:
Dam:
- Abortion: 2nd trimester
- Premature, weak, still born
- Asymptomatic

Calves:
- 95% born normal
- No CS > 2 months of age
- PI calves
- Proprioceptive defects, ataxia
- Exopthalmus and eye asymmetry
- Hydrocephalus, spinal stenosis

Diagnose:
- Histopathology
- Serology (positive titres show exposure, not causality)
- Indirect FAT/ELISA: Foetal fluids
- PCR (ag)
- Immunohistochemistry: Foetal tissues

Control:
- Serology on adults/new borns to select for non-carrier replacements
- Test calves at 6 months to eliminate PI
- Control dogs/carcasses
- Embryo transfer for valuable infected cows.
- Test & cull infected
- Vaccination: Not in AUS

What is toxoplasmosis/Theileria?

Toxoplasmosis:
Ingestion of oocysts
Path: Cotyledons have multiple white areas of focal necrosis/calcification
Dx: FAT, histopathology, serology
Control: Reduce cat population & contamination of feed

Theileria
Exotic species: African T
Australian: T. Oreintalis
CS: Lethargy, anorexia, lagging, abort
Control:
- Tick Control
- Avoid Stress/movement
- Avoid moving naive cattle to endemic
- Quarantine intros for 30 days

What are mycotic abortions?

Route: Inhalation/ingestion leading to haematogenous spread to foetus.
CS:
- Late abortion (6-8 months)
- neumonia

Pathogenesis: Placental insufficiency, intrauterine growth retardation

Pathology:
- Chronic diffuse placentitis
- Intercotyledonary thickening
- Cotyledon necrosis

Diagnose: Smears, culture, serology
Control: Good ventilation, avoid mouldy feed

What is Uterine torsion?

Rotation usually 180-270 degrees. In direction of non-gravid horn
Predisposing factors:
- Large foetus
- Multiparous cow
- Large, elliptical abdomen

CS:
- Abdominal discomfort
- Increase pulse/respiration rate
- Delayed cervical dilation
- Rectal palpation: Broad ligament pulled tight over the uterus

Treatment:
< 90 degees: rotate foetus into normal position
< 90 - 270 degrees: Rotate or roll
- 360 degrees: Roll or C section (Preferred due to closed cervix)

Manual Rotation:
Method: Animal is standing, twist via forehead or proximal region of a limb in the opp. direction to the torsion.
Rod Detorsion:
Method: Loop chains on proximal limb, preferably on the distal presenting radius or tibia.
Thread through loop of rod –> use of screwdriver & chain wrapped around the detorsion rod in direction of rotation (avoid tissue)
Detorsion by rolling:
- Used when Torsion up to 360 degrees, cervix is closed and ceasarean undesirable
Method: Cast cow on side of torsion direction, place plank on paralumbar fossa region & stand on it
Tie front + hind legs together. Pull legs up over the recumbent cow.

What is a Vaginal Prolapse?

Risk factors: large calf, pluri-parous, Bos indicus, overweight, low BCS

Host: Beef > Dairy cows or super-ovulated cows

Timing: Late gestation OR post partum or during oestrus (Inceased oestrogen)

Aetiology:
- Progressive: Repeated partial prolapse and return when lying down vs standing
- Swelling, trauma or dryin mucosa –> Straining and enlargement –> permanent prolapse
- High E2 level may cause softening of peri-vaginal region/ligaments
- Involvement of the cervix/bladder

Treatment: Often recurs, should cull

Surgery:
- Initial rectal exam to check if pregnant –> lignocaine epidural –> Clean mass/vulva
- Reduce mass via hyperosmosis and replace once small enough
- Place retention stitch (Buhner’s stitch (loop/knot pattern), shoelace pattern, Minchev procedure/Johnson, Transvaginal cervicopexy). OR pins/buttons but remove close to parturition.

What are other types of prolapse?

Prolapsed Rectum
Cystic vestibular land: Becomes occluded and distends.
Uterine prolapse

What is foetal mummification

Death of a foetus, in the absence of air and bacterial contamination.
Cervix remains closed, no bacterial colonisation of the uterus.
- Resorption of fluid, dehydration of the foetus & tight adherence of uterus to foetus

Cuases: Viral infection e.g. BVD
Clinical signs:
- Anoestrus damn, uterus tight with firm contents & lack of fluid, sunken eyes of foetus, absent fremitys, no placentomes

Treatment:
- Cull if ecnomic
- C-section
- Luteolysis (PGF2a) –> Recheck for delivery or expulsion

Prognosis: Good if expelled without complication
Prognosis is lowered the larger the foetus is

What is foetal maceration?

Death of a foetus with dilated cervix & bacterial invasion

Clinical signs:
- No fremitus or placentomes
- Absent fluctuation of uternine contents
- Putrefaction of foetus: Gas, variable fluid content, brown/smelly discharge, bone fragments on ultrasound/palpation

Treatment:
- Cull as future fertility poor
- Carcass condemnation –> Slaughter and ethics
- C-section: Ventral midline to avoid contamination
- PGF2alpha: may fail due to poor cervix dilation.contractions.

What is hydrops Allantois

Abnormal/rapid increase in allantoic fluid post mid gestation + abnormal placenta.
Reduced number of placentomes
Adventitious placentation: specks next to normal cotyledons. Severe: Multiple random islets of cotyledonary tissue around a normal cotyledon.

CS:
- Bilateral, symmetrical abdominal distension
- Anorexia (compressed rumen)
- Increase in HR, RR –> Recumbency and death
- Rectal palpation: Tight/enlarged uterus. Difficult to palpate foetus

Treatment:
- Gradual fluid removal: Lateral catheter with fluids
- Induced parturition
Prognosis: Future fertility is poor, survival is poor

What is Hydrops Amnion?

More gradual onset
CS Signs:
- Abnormal foetus: Defective swallowing, renal tissue abnormality
- Palpable foetus/placentomes
- Pear-Shaped abdomen

What is Pregnancy Toxaemia?

Primary: Independent of initiating disease
Secondary: Induced by primary disease that exacerbates negative energy balance

Predisopsin factors:
- Twins
- First calf heifers
- GIT Parasite
- Over conditioned beef cows with sudden reduction in feed. OR late gestation pasture quality/quantity is low
- Early autumn calving –> Inadequate nutrition

Consequences: Fatty liver infiltration –> Reduced hepatic gluconeogenesis –> Increased ketogenesis

Clinical signs:
- Ketonuria
- Appetite reduced
- Lethargy
- Ruminal atong
- Recumbent
- Aggressive/stumbling fat beef cows

Treatment:
- Bolus IV glucose or dextrose
- Glucocorticoid admin –> parturition
- Glucogenic subs e.g. glycerol
- Treat concurrent disorders

Prevent: Nutrition
Prognosis Good if ambulating, eating, has quality feed
If inappetent/recumbent: Poor prognosis. Die

What is Uterine Prolapse?

Timing: <24 hours following parturition

Pathogenesis:
- Decrease in uterine tone e.g. hypocalcaemia, twinning, large foetus, hydrops
- Can cause inversion of the uterus.
- Inverted uterus enters the pelvic cavity –> Stimulates abdominal contractions –> Uterine prolapse

Prognosis: 70-80% success, majority are fertile

Treatment: Emergency
- No movement, cover uterus if recumbent, provide water, correct hypocalcaemia + epidural

Recumbent: Sternal recumbency, extend hind legs with stifles down to prevent straining. Faciing downhiill.
Standing: Restrain and elevate uterus to level of vulva
Uterus: Elevate in supporting dish (+ wrap in bag). Clean with antiseptic/saline to reduce oedema, leave placenta attached as removal traumatises caruncles.
Repair significant lacerations with inverting pattern
Replacement: Apply cranial force at uterine base by vulva with mittens
Invert: Once replaced, invert with base of an empty wine bottle by pressuring cranially of each uterine horn end.

Post-operation:
- Administrate IM oxytocin, early return to ambulation reduces risk of re-prolapse.

Uterine Amputation: If extensive trauma has occurred/uncontrollable haemorhage.
Incise uterine wall, avoid caruncles. Ligate large uterine arteries and veins.
Transect broad ligament.

What is a bladder prolapse?

Location: Through rupture/tear in floor of the vagina
Differential diagnosis: Eversion of the bladder through the urethra
Treatment: Epidural, clean, replace, suture laceration
Systemic antibiotics.

What is sacro-lliac subluxation?

Cause: Relaxation of pelvic ligaments –> Ventral displacement of sacrum when cow is mounted
Timing: Uncommon, peripartruient
No treatment

What is post partum uterine infections

Barriers to infection:
- Vulva, vestibular sphincter, cervix
At calving, the uterus is contaminated by variety of pathogenic/non-pathogenic organisms.
Timing: <4 weeks from calving to be cleared

Predisposing factors:
Impaired neutrophil function via reduced DMI during the dry period/poor hygiene at calving –> Uterine inflammatory disease post partum

Prevention:
- Optimise transition diet/ DMI post partum
- Adequate Se/Vit. E
- Good hygiene at calving/dystocia
- Prevent hypocalcaemia

What is the therapy for post partum uterine infections

Antibiotics - Oxytetracycline commonly use
Adv: Maintains activity within debris and anaerobic uterine environment
Dis: Irritant: Can cause inflam of the endometrium
Intrauterine Antiseptics
- Little evidence to justify usage, may induce inflammation
e.g. Alcohol, chlorhex, Iotagen
Hormones:
- Oxytocin: Ineffective > 48-72 hours post calving
Use within first 24 hours following relief of dystocia to promote uterine contraction
- Oestrogen: Ineffective
- PGF2a: No benefit in early post partum period.
Pyometra: Drug of choice –> Cervical relaxation and uterine drainage.
- Progestins: Contraindicated in uterine inflam disease as they reduce neutrophil function in uterus –> exacerbate infection

What is Metritis?

Inflammation of all layers of the uterus e.g. mucosa, submucosa, muscularis, serosa

Risk Factors:
- Retained foetal membranes and factors predisposing
- Reduced feed intake

Main pathogens: E. coli, A. Pyogens, Pepto-streptococci

CS:
- Within the first week post calving:
Large, atonic fluid filled uterus, fever, depression, anorexia, recumbency, decreased milk yield
Red brown water, foul vaginal discharge

Treatment:
- Systemic: Ceftiofour sodium or procaine penicillin, ampicillin

Intrauterine treatment: Oxytetracycline –> controversial whether beneficial
Supportive: NSAIDs, Fluids, Ca/energy supp
Avoid: Intrauterine manipulation to decrease bacteraemia, endotoxaemia and trauma (e.g. oestrogen, PG)

What is Endometritis?

Inflammation of the endometrium & no deeper than stratus spongiosum
Main pathogens: A. Pyogens, F. Necrophorum, Gram: Anaerobes

Risk Factors: Hypocalcaemia, Postpartum negative energy balance, Retained foetal membranes/RFM, Dystocia, Twins, Metritis, Ketosis, LDA

Pathogenesis:
- Infection stimulates immune response which is compromised by post partum neutrophil influence
- Immune response suppresses GnRH and LH secretion: Decreased ovulation
- If cows do ovulate: the CL produces less progesterone and luteolytyic mechanism is impaired via redirection of Prostaglandins from the F to E series.
- Ovulating oocytes have reduced development, embyronic development will be affected by hostile uterine enviro.
- Thus accumulation of neutrophils and bacteria in uterus –> Extended anoestrus/luteal phases
* Bacterial products and endogenous inflam. mediators affect embryo development + disrupt pregnancy
–> Local vascular exchange mechanisms may allow for transfer of mediators from the uterus to ovaries/udde. Decreases fertility.

Consequences:
- Low repro performance
- Increased calving conception interval
- Increased culling

How can you diagnose and treat endometritis?

Diagnose:
- External Inspection: Pus discharge
- Palpation of cervix: Cervix > 7.5cm diameter. Uterus unequal+ large fluid horns
- Purulent material in vagina: 21-28 days PP, Vaginoscopy, manual exam or metricheck
- Evaluation of serum markers: Hepatoglobulin, a1-acid glycoprotein
- Endometrial biopsy: Negative affect on subsequent fertility

Treatment:
- Intrautrin Ab: -28 days post partum: Cepharin
No milk withholding period
PGF2alpha: Variable, some benefit when CL present but no useful <28 days post partum

What is Subclinical endometritis

No visible cervix discharge but cytological evidence of inflam

Timing: 35-60D Lactation Associated:
↓ Preg rate, delayed conception,
↑ % of failed conception

Dx: Saline lavage, cytobrush, ultrasound (Less effective)

Tx: Cephapirin IU or PGF2a

What is Cervicitis?

Exist in cases where there is a vaginal exudate in absence of endometrial inflammation

Risk factors:
- Obstetric complications
- Uperperal metritis

Treatment: Cephapirin

What is Pyometra?

Accumulation of purulent exudate within the uterus with functional CL. Systemic signs absent

Pathogenesis:
- High conc. P4 post-ovulation suppresses defence mechanisms
- Failure of PGF2alpha release from uterus in presence of uterine inflam: Persistent CL

Diagnose:
- rectal palpation: Fluid filled uterus, horns equal, lack membrane slip/placentomes/foetus
- Ultrasound: Hyperechoic fluid within uterus

Treatment: PGF2a to induce luteolysis & drainage
Recurrence occurs 9-13%

Refractory cases:
- Assess vagina via speculum
- Assess uterus for presence of remnant foetal parts, intrauterine adhesions (Ultrasound)
- therapeutic flushes of the uterus until the flow is clear
–> With Foley catheter and sterile saline solution

What is a retained placenta?

12 hours post partum: retention of placenta for approx 6.8 days

Normal uterine involution:
- Placental detachment: 3-6 hours
- Cotyledon proteolysis: 3 days
- Caruncle necrosis: 7 days
- Caruncle sloughing: 15 days
- Collagen breakdown via collagenase
- Epithelial cover of endothelium: 26-30 days

Pathophysiology:
- There is prepartum inhibition of cotyledon proteolysis and neutrophil function
- Ischaemic retained placenta post bird = metabolically stressed placenta with release of inflam. mediators and local immunosuppression
- Bacterial colonisation compounds impact

Potential causes:
1. Uterine atony
2. Oedeoma of chorionic villi (Dystocia)
3. Cellular dysfunction/necrosis (infection)
4. Decreased innate/humoural immunity
5. Oxidative damage via insufficient antioxidants
6. decreased pre partum BCS = decreased a-tocopherol conc., increased NEFA and BHBA conc.
7. Incomplete extracellular matrix by collagenase related to steroid hormone imbalance

What is the treatment and diagnosis for retained placenta?

Diagnose: When >10% prevalence or increase in individual herds –> Investigate

Treatment:
Aim: Early detachment to decrease occurence of metritis, decreased milk yield and reduce negative impact on repro performance

Experimental: infusion of collagenase into umbilical arteries, 85% effective within 36 hours.
- Physical removal: NOT recommended as risk of iatrogenic contamination, residual placental tissues can remain and traumatise the uterus

Hormonal: E2 and oxytocin not effective in placental separation
Intrauterine therapy: Antiseptics can exacerbate inflammation
Oxytetracycline can reduce incident of fever BUT in milk residues for 144 hours

Tetrayclines inhibit matrix proteineases, may PROLONG RFM

Systemic Ab: Recommended if pyrexia,
ceftiofur decreases metritis. No witholding period but expensive.

Procaine peniclin: Cheap but milk residues.

Describe mucous character/odour in metri-check

Mucous character
0 - clear or translucent
1 - clear or translucent with flecks of white pus
2 - <50mL containing < 50% white/cream pus
3- >50mL containing >50% white/cream/bloody bus

Mucous odour
0 - no unpleasant odour
3 - Fetid odour

What are the indications for inducing parturition in cattle?

Preserve the life of the damn e.g. late pregnant cows with metabolic diseases such as pregnancy toxaemia
Reduce dystocia by reducing birth weight in heifers
Mismated animals
Scheduled C-section
Close observation for detection and correction of dystocia
Historical use: Sync lactation, increase milk yield, decrease culling in seasonal herds and improve lifetime production
Prevent excessive udder odeama
Seasonal herds: Once late committed to a lifetime of late calving

What animals are suitable for induced calving and what are the trends/ethics?

Suitable Selection:
- Age 3-8 years that are not replacements
- BCS 4.5-5.5/8
- 6-13 weeks before expected calving
- Healthy
- Dried off for >7 weeks
- Avoid mammary gland infection/mastitis

Trends/Ethics:
- Banned in NZ
- Phased out in AU unless dispensation ranted for exceptional circumstances.
- AVA opposes if not therapeutic

What are the disadvantages of calving induction?

Low birth weight and weaning weight in beef herds
Calf mortality <2 week from due date, welfare
Public attitude
Increased incidence of retained foetal membranes and thus low repro performance
Metritis, hypocalcaemia, dystocia
Treatment with corticosteroids have side effects: mastitis, photosensitisation
Increased calf morbidity/mortality

What are strategies to reduce induced cows?

Exam pre-AI for uterine infection/treat
Oestrus sync protocols
Treatment of non-cycling cows
Nutrition optimised to max health
All other methods to improve fertility: Cross-breeding, genetics, culling, heat detection

What are the guidelines for calving induction?

Ensure labour is sufficient
Ensure human treatment of calves
Preg check all presented
Assess alternatives
<1month from calving
Screen out unsuitable
Ensure adequate dry period & management to prevent hypocalcaemia

What are the methods of inducing parturition in cattle?

Corticosteroids: help decrease placental P4 production
a) Short Acting:
Dexamethasone
Efficiency: 80-90%
Parturition: 24-72 hours
Timing: Close to calving with milk present

b) Long acting:
Timing: >7 months gestation + no udder distension. Often in cows not conceived to AI but to herd bull.
Aim: Decrease cull rate, increase lifetime production
Drug: Dexmethasone trimethy acetate
Parturition: 4-26 Days,
Post-infection: Monitor for 20 minutes for anaphylactic reactions
Dis: Decreased milk production and increased RFM.

*Variability in time to calving after treatment can be reduced by administering PGF2 alpha about 8-12 days after.
BUT calf mortality and incidence of RFM incrased.

PGF2alpha - Help remove CL P4 production
Timing: Last 2 weeks gestation
Parturition: 24-72 hours
Dis: Increase RFM

How can you induce abortion in feedlot heifers?

Animals induced in good health
Up to 150 days: PF2 alpha to induce abortion
Greater than 150 days: Combination of PG and dexmethasone. Abortion in 3-9 days.
Oestrogen: Treatmenet within 2-3 days ovulation disrupts oviductal transport of embryo.
Cause luteolysis up to about 150 with high doses
Intrauterine infusion of an irritant chemical e.g. iodine

What is the InCalf Project?

Research project where data was collected from commercial dairy herds in Australia.

Aim: Understand reproductive performance & major related factors in dairy cows.
Benchmark reproductive performance of dairy cows in Aus.

What are the key measures for overall herd reproductive performance in seasonal/split calving herds + year round herds?

Seasonal/split herds:
- 6 week in-calf rate:
% of cows pregnant after 6 weeks of mating
> 60%

Not in calf rate: % of cows not pregnant at the end of the mating period
< 8%

Year round calving herds:
100 day in calf rate
% of cows pregnant by 100 days after calving
> 60%

200 day not-in-calf rate
% of cows not pregnant by 200 days after calving
7% (<13%)

What are the drivers of overall repro. performance in split/seasonal and year round herds?

Split/seasonal:

3 week submission rate: % of cows receiving at least one insemination in the first 3 weeks of mating
> 85%

Conception rate: % inseminations that resulted in a positive pregnancy test
> 50%

Year round:
80 day submission rate: % of cows that received at least one insemination or mating by 80 days after calving
>73%
Conception rate: % of inseminations that resulted in a positive pregnancy test
>50%

What are the calving pattern targets?

Cows need to calve at least 6 weeks, and heifers up to 9 weeks before mating start date

88% of the whole herd calved by week 6
First calves have 75% calved by week 3, 92% by week 6

What is a fertility focus report?

Addresses: Current position, realistic improvements, what areas need improving
Consists of:
1. Overall herd performance
2. Drivers of in-calf rates –> SR and conception %
3. Key indicators of improvement
3. Summary page

How can you do a macroscopic evaluation of semen?

Volume
Colour
No discolouration or blood, pus, urine discolouration
Consistency
Affected by: Semen production, collection and method (electroejaculation = dilute semen)
Scale:
0 - clear
1- Cloudy < 200
2- Milky 200-500
3- Thick milk 500-1000
4- Creamy 1000-1500
5- Thick creamy 1500 +
Smell: e.g. Urine contamination
pH: Normal pH of bull is 6.2-7.4. Decreases overtime due to build of lactic acid

How can you do a microscopic evaluation of semen?

Mass Activity: Small drop of semen on pre-warned slide with no cover slip
–> Use: reserved for ruminant semen as highly concentrated
–> Calculate: Concentration & motility
Scale:
0 - No swirl
1 - Very slow swiel
2- Slow swirl
3- Moderate Swirl
4- Fast swirl
5- Very fast swirl
Individual motility
a) Total motility: % of sperm moving in any direction
b) Progressive motility: % of sperm moving progressively across the field of view (moving actively forward), assess different parts of the slide
Results: Tick -> 60%, Q -> 30-59%, X - <30%
c) Speed of movement

Method: Dilute sample (warm isotonic) and place on drop on a pre-warmed slide with a coverslip or dip wooden applicator in semen & dilutant.

Morphology
Determining the % of normal vs abnormal sperm whilst immotile
Methods:
a) Wet prep: Drop of semen on slide with coverslip –> Phase contrast or DIC microscope
b) Eosin-nigrosin stain: Mix small semen drop with large stain drop –> place on slide near frosted edge and use blood smear method to spread.
–> bright field microscope

Major defects: Proximal cytoplasmic droplets pyriform heads, folded/coiled tails, mid piece defects, maldeveloped, craters
Result: Tick > 70%, Q - 50-60%, X - <50%

Foreign cell smear: Smear made from raw semen directly or from a pellet of semen after centrifuging
Cells seen: Sperm, neutrophils, lymphpcytes, epithelial cells, spermatogenic cells
Smegma contamination: WBC’s
High no. of neutrophils from sheath ejaculation may be normal, but high numbers if penis is exteriorised/washed is worrying.

Concentration
Results: Tick - > 200, Q - >200, X - < 200
Methods:
- Haemocytometer
Step 1: Dilute sperm in saline/phosphate buffered glutaraldehyde –> Preserved sperm
Step 2: mix well, load an aliquot on eac side of the haemocytometer
Step 3: Count no. of sperm heads within counting area (25 squares) boarded by 3x lines, if too many sperm, count sperm in 5 corner/middle squares and multiple by 5
ONLY count sperm heads in contact with upper/left border and NOT lower/right border
Step 4: Calculate concentration taking in dilution factor
= Count in 25 squares x 10,000 x Dilution Factor
(AKA 1:100 factor = x 100)

Other ways of measuring sperm concentration:
- Nucelocounter
- Photometer (Spermacute)
- CASA: Computer assisted semen analysis

What are important definitions in bull reproduction?

Fertile: Can naturally impregnate 60-90% of 50 normal, cycling females within 3-9 weeks respectively
Sub-fertile: Achieve natural pregnancies at a lower rate OR only achieve via AI, not naturally
Infertile: Cannot achieve pregnancy
Serving capacity: Counting no. of successful services in 20 months –> Not ethically acceptable
Serving ability/assessment: Visualise if bull can serve only one cow.

What are the components of a Bull Breeding Soundness examination?

Results:
Tick: Fertile
Cross: Not to standard
Q: Qualifies but doesn’t meet all
NT: Not tested

Physical
- BCS
- Gait
- Eyes
- Conformation: Legs, joints, feet, head, length of prepuce
- Penis:
Method: penis is manually extended by grasping glans tip with gauze once it is extended with the electrojaculator
Normal visualisation (NV), normal palpation (NP) or abnormal (A)
Scrotal
- Palpation: Feel for neoplasia or growths
- Measurement:
Pull testes firmly into lower scrotum with thumbs and fingers loacted either side of the scrotum. Tape is pulled snuggly around the greatest diameter of the scrotum.
OR with a Barth –> 2mm of green piston showing
Depends on: Breed, weight, age
Results: <90% interval = X unless pre pubertal, > 90% CI = investigate further
Heritability of Scrotal Circumference is high = 0.30 to 0.45
Semen
Described as above: Macro, micro and concentration
Impacted by Age: Younger bulls have lower quality
Re-testing: Done > 60 days since last test as spermatogenesis is 61 days
Serving: Visualisation of mating/serves in 10 minutes (For bos taurus) or 20 minutes (for Bos Indicus)
0 serves = Fail
> 1 = Pass
Measures: Libido or physical limitations for successful mating

Method:
- Individually or in groups. Young bulls separate, herds of same social group
- Restrained or unrestrained females
- Females may or may not be in oestrus. If not: Restrained

When recording:
I: Interest e.g. nose curcling, licking, false mounts
M: Mounts: no. of full mounts by a bull
S: Serves: No. of effective mounts with intromission, ejaculatory thrust and dismount with erect penis

Morphology: Sperm

What is the general framework for categorising bull reproductive problems?

Impotentia Coeundi: Conditions affecting desire/ability to copulate
Impotentia Generandi: Conditions affecting bulls ability to fertilise ova

What are conformational, neurological and musculoskeletal disorders of repro system of bulls

Head conditions that impact sight, grazing and maintenance of body weight
Low body condition: reduced libido, testicular atrophy, reduced sperm, delayed puberty
Over conditioned bulls: Accumulate scrotal fat, interferes with temp regulation
Poor conformation: Affects ability to copulate, mount and reduces libido
Rapid growth causes degenerative joint disease

Examples:
- Post-leggedness: Predisposes to stifle & hock joints –> lameness and decreased mounting
- Foot Issues: Cork-screw toe, interdigital fibroma, laminitis, overgrown claws, footrot
- Arthritis:
Distension: Tibiotarsal joint –> resolve or limit serving + correlation with growth rate
Oesteoarthritis: in the distal, intertarsal, tarsometatarsal & stifle joints
Score: Q or F depending on degree, no. joints, signs of lameness–> Re-evaluate to assess resolution and serving ability.

Avoid:
- Rapid growth (>1kg/day) between 6-12 months,
- Feeding excess rapidly fermenting carbs 12-24 months.

Ruptured Cranial Cruciate
Dislocated hips/fractured
Sickle hocks
Ankylosis & Sponylosis of Vertebrae: Sore back –> Improper mounting

What are behavioural disorders of repro system of bulls

Dominance Rank: Dominant bulls preventing lower ranked bulls from mating
Libido: Genetic potential for serving capacity varies between bulls
Immature bulls: have lower libido
Pain, over conditioning. under conditioning

What are external genitalia disorders of the repro system in bulls

Scrotum: All but dermatitis cause swelling

Inguinal hernia: Most common on left side, contents replaceable and not firm unless incarcerated
Orchitis/Epididymitis: +- Sensitive palpation, tesitis larger, firmer than normal
Neoplasia
Varicocoele
Trauma/wound
Hydrocoele: Unknown aetiology, incidental finding no other CS. Self-limiting and will resolve over time.
Haematocele: Irregular hypoechoic (Fluid) & hyperechoic– no heat or systemic Sx, ↓ w/ time
Spermatic cord torsion
Sickle hocks
Dermatitis: Dermatophillus Congolensis, Chorioptes Bovis, Lice → Interferes w/ thermoregulation & fertility, Frostbite → Older bulls more likely

Describe penile problems in bulls

Types of Issues: Congenital, infectious, nerve damage, disruption of erectile process

Examples:
- Diphallus: Duplication of glans penis. Congenital

Short Penis
Short retractor penis muscle
Persistent frenulum
–> Persistent band from median raphe of prepuce near glands w/ blood vessels in the centre.
Normal: Separation of penis from sheath at 1month –> Completes at 8 month.
Consequence: Prevents complete extension & often results in penile deviation
Treatment: Ligation/transection of frenulum. Only treat bulls used as terminal sires.
Hypospadias: Failure of urethra to fuse ventrally: Hole located along penile shaft
Hair ring: Hair located around base of glans: Constriction & stenosis –> Necrosis, irritation
Cause: Homosexual behaviour drawing hair from back of bulls into prepuce
Treat: Removal of hair and local treatment.
Penile Deviation
–> Spiral/Corkscrew: Most common in polled > horned. Onset >1-2 normal breading seasons.
Can occur during electrojaculation, can diagnose as during natural services.
–> Ventral deviation
–> Rainbow deviation
–> Dorsal deviation
Treat: Surgically correct via apical ligament splitting/interweaving or fascia latae autographs. Not recommended as likely genetic.

What is penile haematoma?

Swellings of the Prepuce

Penile Haematoma: Rupture of tunica albuginea allowing blood to escape from corpus cavernosum
CS: swelling cranial to scrotum + Preputial prolapse
Location: Site of rupture is the dorsal penile surface opposite attachment of the retractor penis muscles
Cause: Downward penile deviation during mating or bent while thrusting into hard surface

Diagnosis: Cranial to scrotum can see abscesses
Ultra sound: Signs of clot formation, no definitive capsule with haematoma
Fine needle aspiration: AVOID. as can inoculate site with bacteria –> formation of abscess

Treatment:
- Sexual rest
- Surgery
- Slaughter
- Hydrotherapy
- Antibiotics to prevent abscess formation

Guide:
- If haematoma <20cm in diameter, >70% may recover with antibiotics + 6 months sexual rest
- If haematoma > 20cm, about 50% will recover with antibiotics and sexual rest

Complications of penile haematomas:
- Peripenile adhesions due to fibrosis
- Abscessation
- Erection failure
- Loss of sensation to penis due to damage to the dorsal nerves of the penis

What are some other problems of the prepuce in bulls?

Penile Wart/Fibropapilla
Cause: Bovine Papilloma Virus
Hosts: Young bulls in groups
Consequences: Pain/bleeding during servicing, paraphimosis, penile trauma
Treatment: Often spontaneous resolution or surgical removal, ligation/removal if pedunculated
Cryotherapy, cautery, laser surgery, wart vaccines
Balanoposthitis
BHV-1.2 caused
Transmission: Venereal, AI
Clinical signs: Coalescing vesicles with yellow-white fibrinous exudate –> Extensive haemorrhage/ulceration
Phimosis: Inability to protrude penis
Cause: Persistent frenulum, preputial orifice stenosis, immature
Paraphimosis: Inability to retract penis
Cause: 2nd to trauma causing preputial stenosis

Desensitisation of the glans penis
- Cause: Trauma to dorsal nerves, hair ring, artificial vagina, penile haematoma, severe balanoposthitis
Clinical signs: Trouble locating vagina, may not thrust/ejaculate. Decreasing libido

Prolapsed prepuce
Bos indicus have pendulous prepuce –> Relaxation and preputial protrusion –> Trauma
Preputial Injury:
Treatment: Systemic/topical antibodies, anti-inflammatories, hydrotherapy, bandaging

What are testicular problems in the repro system of bulls?

Causes:
- Congenital: Free-martinism, Abnormal karyotype
- Endocrine
- Febrile
- Aging
- Toxicants: Heavy metal, cadmium, griseofulvin, ethylene, cottonweed, locoweed
- Hormones: Oestrogen, androgen
- Inflammation: Pampiniform phlebitis, frostbite, dermatitis, trauma, biopsy

Testicular fibrosis:
Scale: 0-5 severity
Timing: Common >10m (7-40%)
Consequences: Minimal effects on semen unless >4

What are disorders of internal genitalia in bulls?

Problems of the accessory sex organs

Seminal Vesiculitis
Common in young bulls
Cause: T. Pyogens

Route: Ascending, descending, direct invasion, congenital abnormalities, haemtogenous

CS:
- No obvious signs
- Increased size/firmness of glands on rectal palpation
- Excess WBC/pus in semen
- Abscessation –> Fistulation (rectum, bladder, peritoneal, ischiorectal fossa) –> Bloody poo

Treatment:
- Many spontaneously recover
Surgery: Vesiculectomy: Variable results
- Medical: Unrewarding
- Intraglandular injection of Ab has no benefit
- Systemic antibiotics: Penicillin, tilmicosin, trimethoprim, erythromycin, IV fluoroquinolones

What are the uses of embryo transfer?

Genetic Improvement
Adv: Doubles genetic gains, reduced generation intervals using heifer donors.
Performance: Embryo transfer bulls are compared to ET derived sisters rather than daughters
The rate of genetic improvement can be determined by:
a) Selection intensity
b) selection accuracy
c) Genetic variability
d) Generation interval
Disease Control: zona intact, washed embryo will not transmit infectious diseases
Distribution and transport of valuable genotypes: Cheap import/export of disease free stock
Number: 600,000 in 2002 after freezing + thawing.
Conservation and insurance of valuable animals
Research: Embryo development, endocrine control, clones
Improve fertility: Infertile/sub-fertile cows can reproduce via embryo harvest
Diagnosis of infertility: Repeated failure to collect embryos in ovulation –> Non-patent oviducts
Efficient use of sexed semen: Recovery rates are lower due to short lifespan of semen in reproductive tract + Low doses.
Bypass Embryonic mortality via heat stress

What are disadvantages of embryo transfer?

Cost
Labour Intensive
Unpredictable in response to superovulation
Requires Skill
Can delay calving to conception intervals in donors and recipients.

What are the average no. of transferable embryos collected per flush

Average no. transferable embryos/flush: 5-6
No/Non-viable embryos: 25% of donors

Recovery: 70% of embryos recovered from 40% best donors.

What occurs in step 1 of the sequence of events involved in embryo transfer?

Selection of Donors
- Genetic merit
- Repro normal
- BCS
- Virgin heifers require >2 cycles, 18-24 day inter- oestrus interval
- Postpartum interval: >50 days
- Cervix passes catheter (15 months)
- History: Successful donor in the past?

What occurs in step 2 of the sequence of events involved in embryo transfer?

Superovulation of Donors
Aim: produce max no. of embryos that result in high preg rates post thaw/transfer by synchronising ovulation in super-ovulated donors & normal ovulating recipients

Increase results:
- Strat treatment of donor 9-12 day of the cycle (new wave emerging)
- Follicles >2mm in diameter
- Absence of large dominant follicle
*Initiation of superstimulatory treatments at the time of wave emergence enhances the response.

Insemination of Donors:
a) AI: 4hrs after onset of oestrus, 12 hours inbetween inseminations
b) Inducing ovulation: inseminate 12hrs after GnRH, and then again 12 hours later
c) Optional: Additional AI 36hrs post oestrus

Assessment of Superstimulatory Response:
Count CL’s: Palpation or US, accuracy decreases >6 CL’s

Poor Response to Treatment:
- Compliance of protocol, dosages, site of admin
- Improve nutrition
- Time of year
- Try again Post Calving

Methods to sync follicular emergence before starting superovulatory treatments?
- GnRH: 1.5 days prior
- Follicle Aspiration: 1-2 days prior
- Oestradiol benzoate/17B oestrodial + P4: 4 days prior
- Slow release GnRH agonist: Down-regulation of anterior pituitary: 7 days prior

Methods of Super-Stimulation:
1. eCG
Dis: prolonged 1/2 life causes prolonged ovarian stimulation, high no. anovulatory follicles & low embryo quality

FSH:
Timing: FSH treatment for 4 days.
Decreasing doses & PG admin at 2-4 days, 1-2x a day
Removal of CIDR and onset of Oestrus: 12-24 hours.
Doses: Lower in bos indicus + heifers. High in superovulation/low embryo quality

What occurs in step 3 in the sequence of events involved in embryo transfer?

Embryo Collection
Timing: 6-7 days post oestrus for ideal developmental stage
Prepare: Restrain in crush, no sedation but if needed acetylpromazine.
Epidural

Empty rectum if distended with faeces, wipe vulva with water, catheterise uterus

Methods of Recovery:
a) Body flush: Balloon is inflated within uterine body
b) Horn flush: catheter is passed into uterine horn, balloon is inflated and horn is flushed. Then again on opposite horn.

Flushing technique:
a) Interrupted Syringe: infusion followed by recovery of fluid with 60mL syringe. Repeat process 4x
b) Interrupted Flow: Catheter is connected to Y-piece, connected to tubing and then connected to a bag containing flushing media. Water is recovered through a filter to isolate embryos.

What occurs in step 4 in the sequence of events involved in embryo transfer?

Evaluation of Embryos
Principles of Embryo Handling: Avoid light, distraction, dust, bacteria, chemicals & use labels, clean equipment/fluids, rinse catheters, careful movement

Embryo stages commonly transferred into ET recipients:
Stage 4: Morula
Stage 5: Early Blastocyst
Stage 6: Blastocyst
Stage 7: Extended blastocyst

Can grade Embryo quality from 1-4:
Grade 1: Excellent/Good – Symmetrical, spherical, individual cells w/ uniform size, colour, density, smooth pellucida, no adherence; 85% cell intact, viable mass

Grade 2: Fair – Mod abnormal embryo shape & cell size, mass, colour, density; 50% intact, viable mass

Grade 3: Poor – Major irregularities, 25% material intact, viable mass

Grade 4: Dead/Degenerating – Degen embryos, oocytes or 1-cell embryos, non-viable

What occurs in step 5 in the sequence of events involved in embryo transfer?

Oestrus (36hrs prior - OR 12hr after donor)
BCS, gaining wt.
Readable (Double) identification
Medium or large frame: reduce risk of dystocia
Quiet temper

AVOID:
- History of infertility
- Anoestrua
- Reproductive culls
- Poor PCS
- Early post partum <50 days

What happens in step 6 in the sequence of events involved in embryo transfer?

Embryo processing: grading, washing, (± splitting, freezing, sexing)
Transfer of embryos

What are methods used for controlling the sex of offspring?

Sexed Semen
Method: X/Y sperm separated by flow cytometry as X-sperm have 4% more DNA
Timing: Optimally inseminated close to time of ovulation

Adv:
- Increase pool of replacement heifers
- Higher preg rates
- Reduced dystocia
- Increased genetic gain by 15%
- Decreased no. of unwanted males

Dis: Higher costs, reduced viability of semen, limited no. of sires

Optimise results: Careful Handling

Embryo Sexing:
Method: PCR analysis on embryo biopsy to determine sex prior to embryo transfer
Dis:
- Embryo damage: decreased pregnancy rates and freezability
- Time consuming
- Skill & special equipment
- Sexed semen in the future may reduce need for embryo sexing
Foetal sexing
Goal: Diagnosing the sex of existing pregnancy to make management decisions
Optimal: Cattle 60-80 days
Method: 120-125 day transrectal Ultrasonography or >120 day transabdominal ultrasonography

Anatomical landmarks:
- Genital tubercule: precursor to clit & vulva in female or penis in male
Hyperechoic and bi-loped
In female it is ventral to the tail, male it is caudal to the umbilicus

Gender Specific Structures
Female: Clit, mammary gland, gonads –> Blood flow in peripheral medulla of ovary

Male: Prepuce, penis, scrotum, gonads –> Blood flow restricted to central blood vessels

What is In-Vitro Production of Embryos (IVF)?

Aspiration of oocytes from ovarian follicles
In–vitro maturation of oocytes
In-vitro fertilisation
In-vitro culture of zygotes to morula or blastocyst stage
Transfer of embryos to recipients

Adv:
- Can generate more embryos
- Can be used early post partum (>30 days). Good for juvenile heifers that are too small for ET
- Terminally ill/Slaughter cows
- Ovaries from abbatoir acn be used
- Alternatives to ET

Dis:
- Oocytes require transport to specialist lab & transported back for culture + Fertilisation
- Preg rates low
- Cyropreservation reduced preg rates
- More expensive
- success rates are low in horses via low oocyte fertilisation

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