Cattle Flashcards
What has happened to fertility as milk yield has risen?
Decreased
How many days is the window to get a cow pregnant? How many services can you fit in this time?
45-85 days post calving - 3 services
What is the submission rate?
% who get pregnant in the 2-month window
In what kind of calving does submission rate not matter?
Year-round
What % should oestrus detection be?
80%
What % is oestrus detection actually?
50%
At what age is first puberty?
10-12 months (5-20 months)
At what % adult weight is first puberty?
50% beef, 35-45% dairy
Which breeds have early puberty?
Dairy
At what age should you first serve a cow?
15 months
At what % adult weight should you first serve a cow?
60%
What % of adult weight should a cow be when she first calves?
100%
What are freemartins?
XX/XY chimaeras
What is fertility like in male and female freemartins?
Heifers infertile, bulls subfertile
How can you identify a freemartin?
Palpation, ultrasound, genetic test
What is the clitoris like in a freemartin?
Enlarged, hairy
What is the cycle length in a cow?
21 days
What are days 16-17 like in the cow cycle?
Luteal with high progesterone
What are the 4-5 days after luteolysis like in the cow?
Follicular
Which are the only follicular waves which ovulate in response to oestrogen?
The dominant ones
Which two substances are exchanged between the ovarian/uterine vein and artery?
Oxytocin and PGF2a
What % of pregnant cows will still show signs of oestrus?
50%
What does a normal, active ovary resemble?
Walnut in shell, knobbly
What does a less active ovary resemble?
Hazelnut
What does an ovary in anoestrus resemble?
Small, smooth, hard pea
What can you feel before the corpus luteum fills in?
Ovulation fossa
How many days does the corpus luteum last for?
17
What is mature follicle like on ultrasound?
Anechoic (black)
Between what days is a CL sensitive to PGs?
4-16 days
What does a CL look like on ultrasound?
Solid
What do the ovaries feel like at oestrus?
Feel longer (uncurl) and have increased tone and pulled towards uterus
Where might you see the clear mucus bulling string?
After rectal exam or crusted on the tail
What has happened if there is blood in the bulling string?
Follicle has ruptured so missed oestrus, now in metoestrus
For how many hours does a cow come bulling?
6-24 hours
For how many hours does mounting take place?
15 hours but range is 2-30 hours
What time of day does mounting occur?
Late evening
How many hours after oestrus does ovulation occur?
12 hours
How many hours do sperm take to mature/reach target?
12 hours
How many hours after oestrus do you do AI?
12 hours
At what part of oestrus is peak fertility?
The end
In which direction do you aim the AI gun?
Pull cervix cranially to straighten things out, wiggle gun through cervical rings and aim dorsally
What are three strategies to manipulate the oestrus cycle?
Lyse CL with PGs/oestrogen, provide exogenous CL with progesterone, support follicle/CL with GnRH/GH
In the “estrumate” method, how far apart are the two injections?
11-14 days
How long after the injections is oestrus in the estrumate method?
2-5 days
What is the active ingredient of estrumate?
PGF2a for luteolysis
On which cows does estrumate not work?
Early/late CLs, anoestrus cows
On which cows should you use estrumate?
Heifers
What two things do progesterone implants deliver?
Progesterone and a luteolytic agent
How long after progesterone implant removal does oestrus occur?
2-3 days
In which cows does progesterone implants work?
Anoestrus
What is a PRID?
Progesterone-releasing intravaginal device
Why should you not use a PRID over 12 days?
Suppresses fertility
Why is a PRID combined with a luteolytic?
Because CL could naturally survive for 16 days
What are the two components of a PRID?
Progestagen coil and oestrogen tablet
What is an occasional problem with a PRID?
Vaginitis
What is a CIDR?
Controlled intravaginal drug releasing device
What is a Crestar?
A gun and ear implant
Which kind of cow is a Crestar for?
Suckler
WHat are the two ways GnRH/LH work?
Either support the follicle for ovulation OR support the CL for increased progesterone to increase implantation success
How many doses of GnRH/LH must you give?
Repeat
WHat happens to a cow given GnRH/LH if not pregnant?
Reverts to anoestrus
WHat is the active ingredient of Receptal/Busurelin?
GnRH
What is the active ingredient of Ovsynch?
GnRH
How many doses of Ovsynch do you give?
Two doses 10 days apart with/without PGF2a on day 7
What should you not synchronise freemartins with?
Prostaglandins
What body fluids can you use for a progesterone assay?
Milk, blood, urine
Why is a progesterone assay 100% accurate for negatives?
If low progesterone can’t be pregnant
What can cause false positive on a progesterone assay?
Pathology or missed oestrus
Which mode is rectal ultrasound?
B
At what age are ovaries lost to rectal?
4.5 months
Which side is the CL compared to the foetus?
Ipsilateral
Is uterus consistency or size a better indicator of pregnancy?
Consistency
How many cotyledons does a cow have?
About 80
How long does stage 1 parturition take?
4-24 hours
How long does stage 2 parturition take?
30 mins - 3 hours
How long does stage 3 parturition take?
12 hours
What initiates the endocrine changes before parturition?
Fetal cortisol
What happens to the P:O ratio before parturition?
Falls
What are the two functions of PGF2a during parturition?
Lyses CL and initiates myometrial contraction
Where are oxytocin receptors expressed?
The uterus
Why does tail head rise before parturition?
Pelvic ligaments relax (sacrosciatic ligament)
Why are calves already in birth orientation in the first stage?
They are there throughout gestation
Which is the first water bag?
Chorioallantois
What colour is the chorioallantois?
Blue, vascular
What are the three Ps of fetal orientation?
Presentation, position, posture
What are possible presentations?
Ant/post longitudinal, transverse, vertical
What are the three options for position?
Dorsal, ventral, lateral
What % is dystocia incidence?
3-10%
What can cause uterine inertia?
Low Ca, torsion
If feto-pelvic disproportion, what is the maximum time before term you can induce?
7 days
How much weight does the fetus gain per day before term?
1kg
Why should you avoid overfeeding the cow?
Reduces birth canal width
What BCS should the cow be at calving?
3-3.5
What angle is the widest part of the pelvis at?
45 degrees
How do you delay parturition to correct presentation?
B2 agonist and epidural
What % of cows get failure to dilate?
10%
Which kind of cows fail to dilate usually?
Heifers
What is hydrops?
Excess fetal fluid (amnion or allantois)
In which direction is uterine torsion usually?
Toward the non-gravid horn
Which horn is pregnancy usually?
R
What is Schistosomus reflexus?
Exterior intestines
What is anasarcus?
General oedema
Which breed gets inherited anasarcus?
Ayrshires
What are two methods of inducing parturition?
Lyse CL with prostaglandins (first 250 or last 50 days) or corticosteroids between these
What risk increases if inducing?
Retained membrane
For how long after parturition does body weight decrease?
50-100 days
What should BCS be at first service?
2.5
Why is manual retained membrane removal not recommended?
Reduces fertility
How do you treat cystic ovarian disease?
GnRH (follicular) or PGF2a (luteal)
How large are luteal cysts and what is a symptom?
3mm, doesn’t come bulling
How large are follicular cysts and what is a symptom?
2.5cm, too much oestrogen so persistent bulling
What are the two types of cyst in cystic ovarian disease?
Follicular or luteal
What % of cows become pregnant in 3 cycles?
90%
What % of bulls are sub-fertile?
20-35%
What happens to the frenulum at puberty?
Breaks down
What is the scrotal circumference at puberty?
28cm
What is the peak scrotal circumference and at what age is this?
34cm at 3 years
What is the minimum sperm motility at puberty?
10%
How many sperm are there at puberty?
50 million
Which cells produce testosterone?
Leydig
How many sigmoid flexures does the penis have?
2
What are the four accessory sex glands?
Cowper’s, prostate, ampullae, vesicular
How long does intromission last?
1-3 seconds
How many times per week do AI centres collect?
2
What is the maximum number of times per week for natural service?
4 (2-3 if under 14 months)
How many calves per bull in seasonal calving?
30
How many cows per bull for all-year calving?
60
Which herds have sweeper bulls?
Large AI dairy herds
What causes penile vibriosis?
Campylobacter (C fetus venerealis)
What should the angle between the penis and abdomen be?
Less than 45 degrees
What has happened if the angle between the penis and abdomen is too high?
Dorsal ligament is damaged
Which direction is the usual penis deviation?
Right
What is balanoposthitis?
Penis infection
What is hypospadia?
Urethral fistula, gives urine burns
How much does a 35cm testicle weigh?
450g
How much weight does each 1cm of a testicle add?
37g
What is wrong if the epididymis is hard?
Chonic infection
What do testicles look like on ultrasound?
Homogeneous
What does an epididymis look like on ultrasound?
Moth-eaten/lace
What causes a testicular granuloma?
Reaction to sperm
What happens if you stroke vesicular glands?
Reflex extrusion
What five structures can you feel on bull rectal?
Ampullae, vesicles, prostate, urethra, inguinal rings
Which side do you stand during a serving ability test?
Right
How many services should you do in a serving ability test?
Two in 20 mins
What is the best way to collect semen?
Artificial vagina
What is the next best way to collect semen?
Electroejaculation
Which volume of semen must you collect?
5ml
How many sperm do you need for a straw?
20 million
What % motility do you need in a semen sample?
70%
What is sperm pH if sterile?
Neutral
What happens to cytoplasmic droplets as sperm matures?
Lost
What should % weight be at first service?
60%
What should % weight be at first calving?
85-90%
How long after calving do you do the pre-breeding exam?
21 days
How soon after calving should a cow so oestrus?
Within 45 days
How long is the voluntary waiting period after calving?
6 weeks
How long after calving is the first ovulation?
7-10 days
Within how many days after calving should a cow be serviced?
70 days
At what time points should you PD?
From 30 days after service, then 10 weeks, then at drying off
What information is it a legal requirement for the farm to hold?
Cow ID, last calving date
What information is it a legal requirement for the AI company to hold?
Dates of insemination
Which value is more accurate than calving interval?
Calving to conception + gestation
Which cows are NOT included in the calving interval data?
Those culled for failure to conceive - only successes are counted
Which two values make up the calving to conception value?
Voluntary wait + breeding to conception
When are the inter-service intervals?
18-24 and 36-48 days
How can you check the accuracy of oestrus detection?
By milk progesterone testing (should be none)
What age is male puberty?
9-10 months
By what age should a bull be working?
2 years
