Ruminant Flashcards
What percentage of beef cattle are bred naturally? What percent are bred AI?
Natural ~93%, AI ~7%
What percentage of dairy cattle are bred naturally? What percent are bred AI?
Natural ~25%, AI ~75%
What are the advantages of natural service breeding?
Doesn’t require specialized training, doesn’t require heat detection/hormone manipulation, has improved conception rate, creates less narrowing of genetic base, allows animals to express natural behaviors
What are the advantages of AI?
Rapid genetic improvement, allows access to “proven sires”, reduces genetic defects and disease transmission, removes the need for male management, provides prolonged use of sires
What are signs that may help detect estrus?
Standing to be mounted (occurs 12 hours prior to ovulation), mounting other cows, increased activity, vocalizing, clear mucoid vaginal discharge
What aids can be used in estrus and mating detection?
Tail paint/chalk, color indicators, pedometers, surgically altered bulls, other activity monitors
What is the estrus detection rate?
cows inseminated / # cows expected to be cycling every 21 days (should be 60-70%)
What factors may impact heat detection?
Housing, footing, lameness, heat stress, and employee accountability
Describe the process of artificial insemination
Semen collected at bull studs with artificial vagina -> diluted with extended -> frozen in 0.5mL straws -> stored in liquid nitrogen -> intrauterine deposition through rectovaginal approach
Define conception rate
cows pregnant / # cows bred (goal is 50-60%)
What are potential reasons for poor conception rates?
Improper semen handling, poor heat detection, poor insemination technique, poor fertility in cow herd
What is the goal of estrus synchronization?
To induce estrus without impacting fertility (reduces the amount of time needed for estrus detection but doesn’t eliminate the need for it)
What would you use to induce estrus?
Prostaglandin F2a- 2/3 will come into heat 2-5 days after injection; give second injection in 2 weeks and 80% will come into heat (works by lysing the CL). Can also add in progesterone (MGA in feed) but not common anymore. Now commonly use a CIDR- mimics CL, pull it out and they go into heat.
Describe the OvSynch protocol
Day 0- GnRH (ovulates any dominant follicle, recruits next wave); Day 7- PGF-2-alpha (luteolysis); Day 9- GnRH (ovulation); Breed 12-16 hours later
When might someone use embryo transfer in a cow? How would it be done?
Used for high genetic value animals. Perform trans-cervical deep intrauterine deposition of frozen thawed or fresh 7 day embryo (7 days after her observed heat)
What percent of dairy cattle are bred off of observed heat (as opposed to timed AI)?
55% off observed heat, 45% off timed AI
What are the reproductive goals for dairy cattle?
Breed heifers by 13 months old. Calf every 13 months. Heat detection rate 60-70%, conception rate 50-60%, pregnancy rate 30% (per heat cycle)
What time of the year are dairy cattle bred?
Year round
Are beef cattle bred year round?
No- have a defined breeding season
What is the goal pregnancy rate for beef cattle during breeding season?
90-95%
What happens to dairy cattle that don’t breed successfully? Beef cattle?
Dairy- try re-breeding. Beef- probably culled
At what point can you detect pregnancy via rectal palpation?
Day 35+
At what point can you detect pregnancy via trans-rectal ultrasound?
Day 24+
At what point can you perform fetal sexing with trans-rectal ultrasonography?
Days 55-85ish
What could you successfully use radioimmunoassays to detect pregnancy? How do these work?
Day 24+, they detect pregnancy specific protein, may have some false positives if recent abortion
What are the 4 positive signs of pregnancy on rectal palpation and at what times do they occur?
Amniotic vessel- day 35-65. Membrane slip- day 35- term. Fetus- day 65 to term. Placentomes- day 85 to term.
What are supporting signs of pregnancy on rectal palpation?
Asymmetry of uterine horns, uterine fluid, fremitus/enlargement of middle uterine artery, presence of a CL
What are the advantages and disadvantages of pregnancy detection via rectal palpation?
Advantages- low cost, accurate, can diagnose pathology (pyometra, ovarian cyst, lymphosarcoma, uterine abscess, adhesions). Disadvantages- physically demanding, requires training, potentially detrimental (abortion, atresia ani), not pleasant for cow.
What are the advantages and disadvantages of pregnancy detection via trans-rectal ultrasound?
Advantages- determines pregnancy status at earlier fetal age, better determination of health/viability of fetus, diagnosis of sex, twins, or fetal abnormalities, better assessment of ovarian and uterine structures, less physically demanding for practitioner. Disadvantages- high equipment cost, technical training required, still not pleasant for cow.
When do short-day breeders kid/lamb?
Spring
Is the breeding management of small ruminants more similar to dairy or beef cattle?
Beef- natural cover
How many offspring can you expect from small ruminants a year?
1-3, varies based on breed, increases with age. Goal average is 1.5-2/year
Describe artificial insemination in small ruminants
Synchronization less dependable than in cattle, transcervical AI is more difficult, laparoscopic AI can be used.
True/False- twins are most commonly dizygotic
True
Twinning increases the risk of…
Abortion, dystocia, postpartum complications (retained placenta, metritis, displaced abomasum), freemartinism (male and female twin, male hormones make female twin sterile)
Describe uterine torsion
Rotation of uterus on long axis- pregnant horns move up and over non-gravid horn
What are the risk factors for uterine torsion?
Hilly pastures, use of tilt tables in pregnant cows, tie-stall housing
What are the clinical signs of uterine torsion?
Prolonged stage 1 or stage 2 labor, rarely painful, +/- twist in vagina
How is uterine torsion corrected?
Vaginally, with detorsion rod, using a C-section, or using the “plank in flank” method (press plank into cow, rotate cow while keeping plank still)
How does a fetal mummy occur?
When fetal death occurs after ossification and the uterus remains sterile. The fluid is resorbed, the CL is maintained, and the cervix stays closed. Presents with firm mass in uterus. Treat with PGF2a.
Which is more common- hydrallantois or hydramnion?
Hydrallantois ~85% of cases, hydramnion only ~10%
What are predisposing factors for vaginal prolapse?
Genetics, obesity, multiple fetuses, poor feed quality