Ruminant breeding management Flashcards
Goal of dairy breed management
Purpose is year-round production of milk
Lactation follows parturition
Goal is to maintain a 13 month calving interval per cow
The goal in the dairy industry is to maintain a ______ ________ calving interval per cow
13 month
2 months Voluntary wait period + ~9m pregnant + ~2m to get pregnant again (ideally less than 30 days) = 13 month calving interval
AI more commonly performed in which type of cow?
Dairy
Easy to handle for heat detection and/or estrus synchronization
Don’t require a bull on site
Able to use sexed semen (if need replacement females)
Main factors that affect reproductive performance in dairy cattle
Voluntary waiting period (VWP)
Insemination rates
Pregnancy per AI
Pregnancy loss
Voluntary Waiting Period in dairy cows
Set amount of time post-partum that an animal is not being bred
Usually around 60-80 days
Factors: herd pregnancy rates, parity, milk production
Allows uterus to recover from infection & involute
Allows cow to achieve positive energy balance and resume cycling
The Voluntary Waiting Period in dairy calves is typically ___-___ days
60-80
~90-95% of all cows should be inseminated within 30 days of the VWP if combining….
Estrus detection and timed AI
Dairy Records Management System (DRMS) important for tracking
Purpose of Beef Breeding Management
Purpose is sale of calves at weaning
Defined breeding seasons – aide with marketing
Spring calving – breed May to August
Fall calving – breed December to January
Easier to identify herd problems (calving distributions)
Beef cattle are commonly bred in the ______ and calve in the _____
Spring calving – breed May to August
Fall calving – breed December to January
Easier to identify herd problems (calving distributions)
Breeding methods commonly used in beef breeding management
Natural – most commonly used
Limit bull exposure to 60-75 days (3 opportunities to breed)
Can market calves in “groups”
AI (+/- estrus detection) + clean-up bull
Still need to limit bull exposure
Advantages & disadvantages to including AI
Disadvantages of AI use in Beef Herds
Requires estrus synchronization for timed AI (labor & drug expenses)
Handeling
Advantages of AI use in Beef Herds
Easier introduction of desirable genetics
Shortened calving season (50-60% preg rate)
Increased calf uniformity (calving at same time)
-Earlier births during calving season = heavier weaned calves
–Potential increased return of $25-$40 per calf
Beef Herd Reproductive Profile Components
Length of calving season
# days from birth of first calf to the birth of final calf
of calves born in the calving season divided by the # of cows exposed during the previous breeding season
-Total # of calves born in a breeding group, including mortalities
-Total # cows exposed in a breeding group
Distribution of births in the calving season
-Timing of births throughout the calving season aggregated to 21-day intervals
Reproductive Goals for Beef Cows
≥ 95% pregnancy success (total)
1st 21 days: 60-65% pregnant (2/3)
2nd 21 days: ~23% pregnant; bull can pick up fertile cows that failed to conceive or maintain pregnancy that have 60-70% chance of getting pregnant still
3rd 21 days: ~7-8% pregnant (remaining cows that have a 60-70% chance of becoming pregnant
% open ≤ 5%
Importance of estrus detection in cattle
To determine when to AI (dairy cattle, beef cattle [rarely], small ruminants, swine)
To confirm that females are in heat before performing AI (i.e., if breeding in large groups); assess response to synch protocols
-Beef cattle, small ruminants
How estrus is detected in cattle
Direct observation of eligible females showing signs together or with a teaser male (behavior)
Detection aids: heat mount detectors, pedometers, etc.
Increased movement & standing
Hormonal assessment
Not practical in production setting
Behavioral estrus signs in cow
Tail twitching or walking with tails elevated
Clear, thick mucous discharge from vulva
Mounting (females in heat should stand to be mounted)
Dairy Cattle: Trained observer should be able to detect heat efficiently by observing the herd for ____-___ min in the morning and evening
30-60
(May want to increase frequency with heifers)
Small ruminants/ swine can check for behavioral estrus 1-2x per day with…
fence line male exposure
Teaser Male Preparation
Vasectomized or Epididectomized
Blocks transport of sperm from testes to urethra/ductus deferens
Advantage: Retains sexual behavior
Disadvantage: Risk of venereal disease transmission
Penile translocation (“Gomer” Bull)
Surgical procedure that transplants the sheath/penis to the fold of the flank to prevent female penetration (usually)
Advantages: Normal erection & behavior; Decreased risk of venereal disease transmission
Disadvantage: bull may become frustrated & lose sexual drive; can “figure out” out to penetrate female (oftentimes performed with a vasectomy)
Factors that affect heat detection in cattle
Adverse weather conditions or sudden change in weather
Malnutrition
Stress (rough handling, transportation, noise, overcrowding, heat/cold stress)
two primary causes of poor reproductive performance and low reproductive efficiency in dairy cattle are…
Failure to detect heat and errors in heat detection
Results of Inadequate Heat Detection
Undetected heats = longer calving intervals, lower lifetime milk production, fewer calves
Breeding cows unsuitable for insemination -> ↓ conception rates and wasted semen and time ($$$)
Combinations of unrecognized estrus and low conception rates may result in inappropriate culling of normal cows
Insemination of pregnant cows mistakenly identified in heat can result in abortion
Heat Detection Rate (HDR) equation
Number of cows bred divided by the number of cows eligible to get bred over a 21 day period
100 cows in a herd are eligible for breeding
35 cows submitted for AI
(35)/100=
Heat Detection Rate = 35%
Conception Rate (CR) equation
The percentage of the number of cows that conceive (actually get pregnant) divided by the number bred at the time of pregnancy check
35 cows submitted for AI
14 cows that were bred become pregnant
(14/35)=
Conception Rate = 40%
Pregnancy Rate equation
The percentage of cows eligible to become pregnant, in a given time frame, that actually become pregnant
Time frame = 21 days (dairy)
Can apply to bull bred herds, AI bred herds, or a combination of both
PR = HDR x CR
14 cows become pregnant
Pregnancy rate = 35% x 40% = 14%
OR
14 cows pregnant/ 100 eligible cows
Artificial Insemination Timing in ruminants
AM-PM rule
If a female is observed in estrus in the AM, she should be bred via AI in the PM
Conversely, if observed in the PM, breed in the AM
Females will be bred via AI and semen placed in the uterine body ~ 12-20 h before ovulation occurs
Sperm placed 12-24 h prior to ovulation
Viability of sperm 24-30 h
Egg viability 8-12 h after ovulation
Reasons for manipulation of the estrous cycle
Convenience (do it all at same time)
Fertility control
Management procedures (know when they calve)
Artificial insemination/embryo transfer techniques
2 main options of manipulating estrus cycle
Shorten the luteal phase
Lengthen the luteal phase
Prostaglandin (PGF2α) agonists can be used to…
Lyse the CL and shorted the luteal phase to get animal cycling and in heat faster (estrus ~3days post admin)
Effective 5-17 of the estrous cycle during diestrus (CL MUST be present and have the receptors present)
Lutalyse (dinoprost) & Estrumate (cloprostenol)
Labor intensive- heat detection is required
Progestins can be used to…
Lengthen the luteal phase (prevent ovulation) - Mimics the luteal phase (makes body THINK there is CL)
(Negative feedback of GnRH)
MGA – oral
Progesterone in oil - injectable
CIDR pessaries – most commonly used
GnRH agonists can be used to…
Stimulates LH/FSH from anterior pituitary
“Resets” follicular wave OR triggers ovulation
Administration AFTER dominant follicle selection- Ovulation
Emergence of new wave in 1.5-2 days- “Resets” the follicular wave
Administration BEFORE selection
-No effect on progression of existing follicular wave
Cystorelin and Factrel most commonly used
OV-Synch protocol
Commonly used in dairy cows
4 handlings
GnRH on Monday (d 0)
PGF on following Monday (d 7)
GnRH again on Wednesday (d 9)
Breed 8-18 hours later
Alterations:
+ CIDR (between GnRH and PGF) (improve efficacy)
CO-Synch protocol
Commonly used in beef cows
Less handling (3)
GnRH on Monday (d 0)
PGF on following Monday (d 7)
GnRH and AI ~54-66 hours later
Alterations
+/- CIDR
Select-Synch protocol
GnRH on Monday (d 0)
PGF on following Monday (d 7)
Heat detect and AI day 6 – 13 (if CIDR not being used)
Alterations
+/- CIDR
Give GnRH and TAI all non-responders 72-84 h after PGF
Artificial Insemination techniques in cattle
Uterine body deposition: 15 million sperm (most common)
Cornual insemination: 2 million sperm (less common unless high value sperm)
Sheep and goats at beginning and ending of breeding season or post-partum will have increased…
Frequency of cycles
More commonly seen in goats than sheep
Photoperiod or nutrition
Estrus duration in sheep
30-36h
Estrus duration in goats
24-48h
Sheep and goat behavior when coming into estrus
Expression of immobilization reflex in response to male nudges, including serial mounting and copulation
Swollen vulva, mucoid discharge turning cloudy
In goats and sheep, When double ovulations occur, usually derived from…
The same follicle wave
Sometimes, can come from two consecutive follicle waves
In More prolific breeds of sheep and goats the dominant astral follicle achieves….
Smaller maximum sizes
Ovulation rate in small ruminants is affected by….
Breed
Season
Nutrition
Estrous Cycle Manipulation in small ruminants is useful for…
Allows for distribution of milk and meat production throughout the year
Labor saving for breeding and kidding
Induction of estrus in transition periods and during winter anestrous
Synchronization for breeding (AI or natural)
Estrous Cycle Manipulation in small ruminants
Photoperiodic Treatments
Male Effect
Dormitory Effect
Adapted Nutrition
Hormonal treatments
NOTE: most drugs not approved for use in goats in U.S.
Combination of all of these
Photoperiodic Treatments in small ruminants
Altering the length of the daylight (need facilities)
Begin with long days to prepare for stimulatory effects of short days (otherwise become photo-refractory)
Decreasing day length will trigger melatonin release from the pineal gland
*works best during transition periods not to keep them cycling because they can have a photo refractory period and stop cycling
Field conditions: melatonin implants
Synergistic with progesterone to induce cyclicity and pregnancy in the anestrous animal
Not available in U.S.
Goats and sheep are more complicated to synchronize since…
They have on average 3-4 waves per cycle
The Male Effect
Brings sheep/ewes out of anestrus period quicker
Ewe and goat isolated for 30 days (no sight, smell, sound) then male introduced
Male introduced abruptly for 48h
Ewes and does pick up pheromones and trigger LH secretion and induces “silent” ovulation (no estrus behavior since no progesterone priming on hypothalamus has occurred)
Works to up regulate estrogen receptor production on hypothalamus so she can respond and show estrus behavior
Ovulation occurred so there is now a CL present to prime the hypothalamus to create more estrogen receptors
Likely short cycle but after she should be able to show estrus behaviors on next cycle since estrogen receptors formed
The Dormitory Effect
Introduction of ewe in estrus
25% of other ewes will respond and come into estrus
Remaining 80% will respond in a few weeks
Great to advance breeding season without the expense of drugs or a ram
Adapted Nutrition “Flushing”
↑ nutrition (energy) before/ early breeding season -> ↑ ovulation rate -> ↑ twinning rate
Feed 1 lb of high-energy supplement (corn, oats, barley etc.) per day @ 2-3 weeks BEFORE BREEDING
Success affected by age, genetics, body condition, time of year
-Best response with marginal body condition
Hormone Treatments in ewe/goats- Prostaglandins
Lyses the CL
Single or double injections, 11-12 days apart- Estrus in 24-72 hours
2nd dose will result in tighter synchrony
*Must be cycling (i.e., in season)
Hormone Treatments in ewe/goats- Progesterone/progestins
Sponges – various products
Medroxyprogesterone acetate
Flurogesterone acetate
CIDR (330 mg) progesterone
Most commonly used in the U.S.
Melengesterol acetate (MGA) in feed
0.25 mg/hd once per day x 14 days
-Legality concerns (extra-label usage)
Length of time is usually 5 or 14 days
Estrus shown in 24 to 96 hours after withdrawal (varies with other components in protocol)
Ovulation Induction during in small ruminants
eCG/PMSG (equine chorionic gonadotropin/ pregnant mare serum gonadotropin)
**FSH-like activity (superovulation)
Acts directly on the OVARY to stimulate ovulation
PG-600: eCG/hCG combined
Longer half-life (36 h) compared to GnRH agonists (0.5-1 h)
GnRH agonists
Acts on the anterior PITUITARY to stimulate LH/FSH activity
Short half-life
eCG in the ewe/sheep acts on the ________ while GnRH agonists act on the _________ _______.
eCG- Acts directly on the ovary FSH like activity (longer T1/2)
GnRH agonist- Acts on anterior pituitary to stimulate LH and FSH (shorter T1/2)
Ovulation Induction during Early Seasonal Transition
Early Transition
Progestin for >14 d (18-21) + PG600® on the day of or 24-48 h before progestin removal
Ewes – 5 day progestin treatment
Ovulation Induction during later Seasonal Transition
Late Transition
Ram/Buck Effect
Progestin treatment similar to early transition
Photoperiod manipulation (begin during summer)
Ovulation Induction Outside of Breeding Season
Progestin for >14 d (18-21)+ PG600® the day of or 24-48 h before progestin removal – sheep 5 days
Artificial lighting programs
Mimic long days for ~ 60 d followed by short days for 60 days or natural light
(Administration of melatonin (not available in U.S.))
Sheep Reproduction Goals
easy management to provide lambs for year-round marketing and increasing production per ewe
Cornell star system- peak efficiency (not done in small settings)
There are three groups of ewes during any 73-day period. The groups of ewes are those that are:
Lambing (first 30 days) and lactating ewes.
Breeding (first 30 days) and gestating ewes.
In the last half of gestation.
Small Ruminant Natural Breeding most commonly used for production of…
Meat and fiber
Small Ruminant Natural Breedings should be planned around desired date(s) of…
Parturition
Male should be left in for 1.5 cycles (32 days in goats or 27 days in sheep)
Male-to-female ratios in small ruminant natural breeding will vary based on…
Age/SC of male
size of mating area
whether females are synchronized (higher male to female if all sync)
Markers useful to keep records for lambing/kidding
Small Ruminant Artificial Insemination deposition
Natural- semen deposited in Vagina
For AI usually use frozen, thawed semen and smaller dose so uterine body deposition preferred
Used mostly for breeding stock producers, hobby farms, and show animals
Fresh semen can be deposited intravaginal, cervical, or transcervical intrauterine
Laparoscopic intrauterine insemination recommended for frozen semen (though acceptable rates can be obtained in goats with transcervical; NOT SHEEP)
Recommended to check quality of frozen semen before use due to lack of standards for quality control
Advantages of AI in small ruminants
Maximal use of superior sires
Elimination of need for males on farm
Inexpensive semen costs
Decreased risk for venereal diseases
Improved herd management
Disadvantages of AI in small ruminants
Cost for AI and semen equipment (LN2)
Increased labor for estrus detection/synchronization/ insemination
Lack of standardized procedures for cryopreservation of semen
Lack of suitable sire proofs for production traits (risk of spreading less desirable traits)
In small ruminants (esp. sheep) need to use _________ for intrauterine insemination
Laparoscopy
Goats may be able to get acceptable rates but not in sheep (cervical ring)
Cervical Rings:
Ewe: 2-7 (avg.5)
Doe: 4
