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292 Cards in this Set
- Front
- Back
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How long does it take an ovine ova to get from the ovary to the uterus?
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2-4 days
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What is the typical age of a sheep or goat at puberty?
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5-7 months
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A small ruminant will usually reach puberty at what % of mature BW?
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66% (2/3)
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True or false: Sheep and goats are seasonally polyestrous.
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True
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How long is the estrus cycle of the sheep on average?
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17 days
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How long does ovine estrus typically last?
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36 hours
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How long does the goat estrus cycle typically last?
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30-40 hours
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How long after the onset of estrus is the optimal breeding time for a sheep?
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18-24 hours
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How long after the onset of estrus is the optimal breeding time for a goat?
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24-36 hours
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How long after estrus starts in the sheep does she usually ovulate?
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24-28 hours
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How long after estrus begins in the goat does she usually ovulate?
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12-36 hours
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How long is the average gestation length in the sheep?
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144-151 days
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How long is the average gestation rate in the goat?
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147-155 days
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How many cervical rings does the sheep/goat have? What is unique about them?
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6-8
Point caudally, so diffucult to pass an AI rod. |
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What is the biggest factor affecting the onset of puberty in the small ruminant?
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Body weight
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Explain why a late (April-May) ewe lamb may not cycle during her first breeding season.
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Sheep cycle in the fall in response to shortened day length. A late ewe lamb's brain may not register the shortening of the days since she has not yet "seen" the seasons and day length change.
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List two sheep breeds known for their higher than average ovulation rates.
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Finns and Romanovs
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How does a ewe in heat appear?
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Seeks out ram
Swollen vulva Generally pretty subtle |
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How does a doe in heat appear?
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Wags tail
Bleats Responds to the "buck jar" of buck secretions Swollen vulva Clear-cloudy-cheesy white mucus |
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What is the significance of a white vulvar discharge in the doe?
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Late estrus, ready to breed!
(NOT pyometra!) |
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What is the way in which most sheep producers determine which ewes have been breed?
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Put a marking harness on the ram-- marks the ewe. (Coitus is very brief and unlikely to be observed)
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What effect does melatonin have on the hypothalamus in the small ruminant?
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Stimulates GnRH production
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How does estrogen contribute to the LH spike?
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Positive feedback on the hypothalamus' surge center--> high levels of GnRH cause an LH spike.
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Melatonin is produced by what part of the brain?
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Pineal gland
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What stimulates the production of melatonin?
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Decreased amount of daylight
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When is the ovulatory period of the small ruminant breeding cycle?
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August- Jan/Feb
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When is the anovulatory period of the small ruminant breeding cycle?
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February-June
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When is the transitional period of the small ruminant breeding cycle?
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June-July
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Describe the cycling pattern of the small ruminant during the transitional period.
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For ~1 month before breeding season, female may go into heat every 8-10 days. Short cycles are like a "warm up."
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What goat breed tends to cycle year-round?
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Pygmy goats
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What sheep breed has the longest ovulatory period?
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Dorsets
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What sheep breed has the shortest ovulatory period?
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Suffolk
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What goat breed has the longest ovulatory period (excluding Pygmy goats)?
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Boer goats
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What goat breeds have the shortest ovulatory period?
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Alpine
Toggenburg Sannen |
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What are some advantages to synchronizing estrus in small ruminant herds?
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Shortening of breeding/lambing season
Timely pregnancy diagnosis Nutritional management Meet market demands Labor efficiency Supervision of lambing Ram management |
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What hormones can be used to synchronize estrus in small ruminant herds?
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Prostaglandins (dinoprost/Lutalyse)
Progesterone (MGA/CIDR) |
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If prostaglandin is the only hormone used in a sheep synchronization program, and two injections are given, how far apart should they be done?
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9-11 days
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If a sheep is given 2 injections of prostaglandin 11 days apart, after how long will she show estrus?
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Within 2 days
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What is the role of prostaglandin in a synchronization program?
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Lyse the CL and cause short-cycling.
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In a CYCLING ewe, for how long should a CIDR be left in for estrus synchronization? What is done after it's removed?
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12 days
Then Lutalyse 20 mg once or 5 mg twice at 3 hr interval |
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In an ANOVULATORY ewe, for how long should a CIDR be left in to induce estrous out of season?
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5 days
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Why is PMSG given to anovulatory ewes and does with progesterone? What role does it play?
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Acts like FSH to stimulate follicular development
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True or false: In order for estrus to be displayed in the ewe, the brain must first be synchronized by progesterone.
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True
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When a ram is introduced to a group of ewes out of season, a "silent" ovulation will occur in 60% of ewes within...
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2 days
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Describe the system in which progesterone is used to induce estrus in the anovulatory season of the ewe or doe.
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CIDR 5d in ewe (14d in doe?)
OR MGA for 14 days+ PG600 at day 12 Introduce male at end of progesterone regime. Heat 1-3 days later |
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For how long should an anovulatory ewe be isolated from a ram before he is introduced to the herd?
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30 days
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Describe the light manipulation method of estrus induction in sheep.
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16 hours of light Dec-late Jan
8 hours of light for 6 more weeks Then turn out sheep |
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Approximately how effective is light manipulation in inducing off-season estrus in ewes?
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40-70% will start cycling in March
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True or false: If manipulating light to stimulate off-season cycling in ewes, the rams should also be included.
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True...rams also have pulsatile GnRH-->LH--> testosteone production in response to light levels
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Describe the light manipulation method of estrus induction in goats.
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16 hours of light for 70d starting mid-Jan
8 hours of light for 70 days Then turn does out |
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Approximately how effective is light manipulation in inducing off-season estrus in does?
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60-70% does will start to cycle by early May
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What are the benefits of incucing estrous in the transitional season in small ruminants?
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Advances the breeding season into the summer months to achieve earlier lambing and an increased market price.
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How are teaser rams used to induce estrus in ewes during the transitional season?
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Send in teaser rams for 2 weeks to get ewes to have silent synchronized ovulations, then add the real ram.
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Describe the dormitory effect in transition-season ewes.
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Take a female in heat, stick her in with transitional females and it stimulated them to go into heat.
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How long after a teaser ram is introduced to a herd will the ewes have their first full estrus?
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18-25 days
(Silent ovulation 2 days after intro) |
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How long does a ewe lactate postpartum.
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120 days, but production drops after day 45
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At what age are lambs weaned in a spring-lambing system?
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8-12 weeks
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What is the benefit of having fall lambs?
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Meet market demand for Jewish and Muslim holidays
Save money by not wintering lambs--> feed with forages |
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This sheep breed has a gene for multiple ovulations.
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Boorola Merino sheep
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Describe the 3-in-2 lambing system. How long is each production cycle?
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3 lambings in 2 years
8 month production cycle -Breed, 5 month gestation -2 months to nurse -Wean and breed back in one month |
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What is the "Cornell Star" breeding management program in ewes?
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5 lambings in 3 years (7.2 month production cycle
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What are some traits for which a ewe may be selected for breeding?
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Extended ovulatory period
SMall size Maternal ability Milking ability Prolificacy Early onset puberty |
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What are some traits for which a ram may be selected for breeding?
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Carcass quality
Growth efficiency Feed efficiency |
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What is a "good" ram-ewe ratio for breeding?
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1:30 to 1:40
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True or false: Stress has no effect on ovulation rate in small ruminants
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False
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When is the point of pregnancy recognition in the ewe?
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Day 12-13
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When is the point of pregnancy recognition in the doe?
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Day 16
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List some ways in which pregnancy diagnosis is made in the small ruminant.
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Marker male
Abdominal ballottement Hormonal analysis (progesterone, estrone sulfate) Ultrasonography |
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After what point in the small ruminant pregnancy can it be detected per ultrasound?
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24 days
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At what point can twins be detected per ultrasound in the small ruminant?
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Day 45
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Besides the fetus, what structure is highly indicative of a small-ruminant pregnancy on an ultrasound?
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Placentome
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True or false: When breeding sheep out of season, the # lambs/ewe tends to increase.
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False. It is lower.
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List some factors causing a poor pregnancy rate in small ruminants.
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Ram fertility
R:E ratio Phytoestrogens Environmantal factors Nutrition Ewe factors Chromosomal abnormalities |
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How long should the first stage of parturition take in the multiparous ewe?
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2-3 hours
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In a primiparous ewe, how long can the first stage of parturition reasonably take?
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2-12 hours
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What occurs during the first stage of parturition in the ewe?
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Lays down and gets up
Paws ground Passes mucus plug Appears uncomfortable "Far-off stare" during contractions Separation from herd |
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How long should the 2nd stage of parturition (fetal expulsion) take in the ewe?
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2-3 hours
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What is the usual interval between twin lambs or kids?
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30-45 minutes
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Once the lamb/kid's feet appear at the vulva, after how long should the observer intervene?
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30 minutes
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After how long is a placenta considered retained in the sheep?
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12 hours
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After birth, how long does it normally take for the sheep to pass the placenta?
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1-2 hrs
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What are the advantages to inducing parturition in the ewe and doe?
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Concentrated lambing for staffing availability--> improves lamb survival.
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What is used to induce parturition in a full-term ewe?
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Glucocorticoids
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What is used to induce parturition in a full-term doe?
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Prostaglandins
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How is abortion induced in the ewe?
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<50d: Prostaglandins
>50d: Dexamethosone |
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How is abortion induced in the doe?
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Prostaglandins, once CL is matured until the end of pregnancy
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How can a mummy and a viable lamb be carried in the same womb?
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Mummy affected individually, b/c own placenta and amniotic sacs. Often develops in own horn, and since mummification is sterile by definition, the uterus and the other fetuses are unaffected
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What steps should be taken when abotion occurs in a sheep herd?
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ID and isolate aborting ewes
Remove abortus-- send to dx lab Wear gloves and wash hands Start herd on tetracycline |
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Why is diagnostic ability for abortion cases (~33%) so low?
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Samples are contaminated or decomposed
Insufficient material Wrong samples submitted Abortion caused by something not detectable |
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How should samples of aborted fetal materials be shipped to a diagnostic lab?
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Whole thing placed in a leak proof container
Chill, don't freeze Submit as quickly as possible |
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Give some examples of teratogenic drugs used in ruminants.
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Albendazole, Cambendazole, xylazine, acepromazine, diazepam
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Abortion due to teratogenic drugs is most likely in sheep before what point in pregnancy? Why?
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Day 35
Most organogenesis occurs in 1st 35 days of gestation. |
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List some causes of early embryonic death in sheep.
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Malformations
Sheep/goat hybrids Toxoplamosis Border disease Nutritional deficiencies |
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List some causes of late term ovine and caprine abortions.
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Enzootic abortion of ewes
Toxoplamosis Campylobacter Salmonella Border Disease Leptospirosis Listeriosis Prolapsed vagina Pregnancy toxemia |
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What causes Enzootic Abortion of Ewes?
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Chlamidia psittaci/Chlamydiophyla abortus
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What agent causes vibrionic abortion?
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Campylobacter fetus fetus
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What agent causes Q fever?
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Coxiella burnetti
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What agent causes border disease?
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Pestivirus
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How is Enzootic Abortion of Ewes transmitted?
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Ingestion of contaminated food and water
Exposure to uterine discharge and fluids |
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How long is the incubation pertios for Chlamydiophila abortus (EAE)?
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50-90 days
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If a ewe is infected with EAE late in gestation, what will happen?
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Deliver normally, but abort the following year.
(Not enough time for placentitis and bortion to occur) |
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True or false: Chlamydiophila abortus is maintained in sheep herds through latent carriers.
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True
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What is the primary source of introduction of EAE into a naiive ovine herd?
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Replacement ewe lambs
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What should be done from a herd management standpoint if a ewe aborts and tests positive for Chlamydiophila abortus?
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Limit exposure to aborted material, isolate infected ewes and lambs.
Treat in-contact ewes with tetracycline Vaccinate herd against Chlamydia next year and use tetracycline in the feed. |
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True or false: The only time that Chlamydiophila abortus is shed by a carrier is when she aborts.
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False. Also in estrus secretions.
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What age group of ewes is most likely to abort first in a Chlamydiophila abortus outbreak?
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Replacement ewes
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This pathogen causes "abortion storms" in sheep herds the year after it is first introduced by infected replacement ewes.
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Chlamydiophila abortus (EAE)
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How likely is a ewe to abort a second pregnancy due to EAE?
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She won't-- immune after initial abortion. (Still a carrier)
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Does Chlamydiophila abortus attach the fetus or the placenta?
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Placenta
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True or false: Chlamydiophila abortus is zoonotic.
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True
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How is Chlamydiophila abortus diagnosed?
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History and clinical signs
Abortus samples on ice Vaginal swabs within 3 days of abortion/parturition-- human Chlamidia test Ab titers |
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How is Campylobacter spread between closed sheep herds?
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Fecal contamination of bird feet
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Campylobacter causes ovine abortion during which trimester?
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3rd (sometimes stillbirths occur at term)
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True or false: Campylobacter is a lifelong infection in sheep.
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True
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How is Campylobacter spread within a sheep herd?
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Food and water contamination
Contact with fetal fluids, fecal material |
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What is the incubation period for Campylobacter fetus fetus?
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7-60 days
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An aborted sheep fetus is autolysed, and has orange-yellow necrotic foci on its liver. What is a likely infectious agent?
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Campylobacter
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How is Campylobacter controlled in sheep herds?
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Strict hygeine
Tetracycline Vaccination programs |
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What other illnesses can befall a ewe that has aborted due to Campylobacter?
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Metritis after abortion, retained placentas
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How is Campylobacter definitively diagnosed?
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Dark field preparation from abomasal, placental, or uterine discharge, FAT
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rue or false: Coxiella burnetti is a zoonotic infection causing ovine abortion.
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False-- it IS zoonotic but does not cause fetal death!
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What are the clinical signs of Coxiella burnetti in sheep?
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Usually none
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What diseases does Coxiella burnetti cause in humans?
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Flu-like symptoms, pneumonia and endocarditis
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How do sheep acquire Toxoplasma gondii?
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Feline fecal contamination of feed--> sheep ingest oocytes
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Describe the life cycle of Toxoplasma gondii
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Cat-rodent life cycle
YOUNG cats shed oocytes 7 days after infection, contaminate sheep feed Sheep eat contaminated feed--> Tachyzoites circulate in body, and bradyzoites form tissue cysts |
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If a sheep aborts due to Toxoplasma gondii, when was she infected?
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During pregnancy
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What kinds of effects does Toxoplasma have on a lamb fetus?
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Mummification, stillbirth, or weak lambs
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What happens to the lamb fetus if Toxoplasma infection occurs in early gestation?
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Fetal death and resorption (may look like infertility)
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How does the placenta appear in the event of Toxoplasma infection before day 70 of ovine gestation?
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Multiple focal necroses on cotyledons that appear like white grains of rice
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What happens to the lamb fetus if Toxoplasma infection occurs in late gestation?
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Lamb has advanced immune system and remains viable, born as an immune carrier.
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How is Toxoplasma gondii diagnosed in sheep?
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Placental lesions on cotyledons= white necrotic foci
Modified agglutination test Immunohistochemical staining |
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How is Toxoplasma gondii infection prevented in sheep herds?
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Spay and neuter barn cats
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True or false: Brucella ovis is a zoonotic disease causing abortion in sheep.
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False. It causes abortion but is NOT zoonotic!
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What is the primary condition caused by Brucella ovis infection in sheep?
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Epididymitis in rams, with granulomatous lesions that block sperm output
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How is Brucella ovis transmitted?
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Infected rams, fetal fluids, infected ewes
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What is the outcome of infection with the Border disease pestivirus before day 65 of gestation in sheep?
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Embryonic death and abortion
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When in gestation does Border disease infection result in a PI lamb?
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Days 65-85
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What happens to a lamb infected with Border disease after day 85 of gestation?
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Immunity, born as "hairy shakers"
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Describe the "hairy shaker" lamb with Border disease
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Straight wool due to wool corpuscle malformation
Cerebellar hypoplasia --> CNS signs |
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What effect does Border disease have on the lambing trends of an infected herd?
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Lambing will be delayed by a cycle or so b/c the early-conceiving ewes will abort and then re-breed late in the season. More open ewes at end of breeding season.
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What is the most significant factor affecting break-even prices in beef cattle operations?
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Increasing the weaned calf crop by 10%
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What is the biggest cause of reproductive loss in beef cattle?
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Not getting pregnant
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Most beef cattle breeding seasons last somewhere within this range.
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45-150 days (ideally 65 days)
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What determines the length of a beef cattle breeding season?
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Climate, nutritional availability, labor, marketing, herd health considerations
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What is the benefit of having a defined beef calving season?
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Allows the producer to present the market with a cohort of similar products, allowing for consistency in finishing the cattle (backgrounded together, feedlot together, etc). Buyers willing to pay up to 10% more. (Retail v. wholesale)
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Why is a shorter beef calving season preferable to a longer one if it gives a cow less time to conceive? Think 63 days versus 105 days.
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All cows get 3 cycles to conceive instead of 5, so any calves born will be born earlier and closer together;. As a result, larger and more uniform in size.
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Describe the strategy for introducing a replacement heifer into a beef cow breeding season program.
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Give her a head start by putting her with the bull before the start of the official breeding season.
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How long does it take for a beef cow to resume cycling after she calves?
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VARIABLE
Anywhere from 15d to over 150d. |
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What is a "good" conception rate per cycle in a beef herd?
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70% CR
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If there is a 70% conception rate per cycle in a beef herd, then what is the final pregnancy rate at the end of a 63 day breeding season?
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98% pregnant
(70 on 1st cycle, 21 on 2nd cycle, 7 on 3rd cycle) |
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Likelihood that a cow will conceive on a given cycle.
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Conception rate
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Percentage of cows that conceive over the course of a breeding season.
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Pregnancy rate
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What happens to the pregnancy rate in a beef herd when most of the cattle do not begin cycling for two months or more postpartum? Why?
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It will decrease, because leaves fewer cycles in which to get pregnant.
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List 6 factors that promote the initiation of estrous activity in beef cows.
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Time of calving
Age of the cow BCS at calving Suckling Presence of bull Use of exogenous hormones |
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Which groups of beef cattle are hardest to get pregnant?
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First calf heifers
Followed by 2nd calf cows and older cows |
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Is it more important for a cow's fertility for her to be in good body condition when she calves or when she is bred back?
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When she calves
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True or false: If a cow is in good body condition when she calves, it is okay for her to lose some weight between calving and breeding.
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True
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Will a cow return to estrus quicker post partum if she is nursing or if she is being milked out?
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Milked out-- the intermittent suckling reminds the cow's hypothalamus that the calf at her side is her first priority.
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What is the only reliable way to ensure that cows have enough time to resume cycling after calving?
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Enforce a short breeding season so that cows breed and calve early in the season.
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Why is it not beneficial in the long run to extend the breeding season so all cows can get pregnant?
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Cows that conceive late in the season will calve late the following season and take even longer to resume cycling and breed back after calving, setting up a vicious cycle.
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What advantages are there to getting cows to calve early in the season?
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Average calf will be older and heavier at weaning.
More uniform calf ages: Management practices become more convenient More size-uniform calf crop at market. |
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How do you transition a beef cattle herd from a year-round calving season to a 63 day season? Include three major principles.
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Gradually
365d to 180d to 150d to 120d...down to 63d. 1. Move some cows back to calving interval of less than 12 mos 2. Let some cows drift forward and extend calving interval 3. Cull cows that don't fit |
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Why do first calf heifers prove a special challenge to a successful reproduction program?
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Continuing to grow
Less body capacity--> less energy intake Slower to return to estrus |
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Will a first calf heifer or a mature cow return to estrus more quickly?
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Mature cow
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What special arrangements should be made when integrating first calf heifers into a beef breeding program?
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Expose more heifers to bull than are needed for replacement.
Feed to reach predetermined target weight before beginning of breeding season Place heifers with bull 20 days before start of cow breeding season for a head-start |
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True or false: A beef cow deemed to be "thin" at calving will return to estrus at the same time as if she were judged to be in good body condition.
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False. She will take longer to return to estrus.
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When should beef calves be removed from the cow in relation to the start of the breeding season?
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48 hours before it begins
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Name a disease state that has a SIGNIFICANT effect on beef cow fertility.
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Fescue toxicosis, aka. "summer slump"
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How does the fescue endophyte act to reduce feed cow fertility? List two ways.
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1. Prevents vasodilation so cows cannot cool--> spend time seeking out cooler areas
2. Depresses prolactin |
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How can a beef producer compensate for the loss of nutrient availability in summer on fescue pasture?
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Stockpile quality hays
Supplemental feeding |
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List three major factors known to influence fertility in beef herds in the absence of disease.
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Time of calving
Weight gain/loss at breeding Bull factors |
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True or false: Weight-gaining or maintaining cows have higher conception rates than cows losing weight at breeding.
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True
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Would you use a higher frequency ultrasound for trans-rectal imaging in a cow, or trans-abdominal imaging in a goat?
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Trans-rectal in a cow, b/c less penetration needed.
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What shape ultrasound probe is best for trans-rectal ultrasound?
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Curvilinear or linear.
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How is a cystic CL differentiated from a luteal cyst?
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Per ultrasound
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This type of cystic ovarian degeneration results in a thin-walled, fluid filled pathologic cyst. The wall is made of granulosa cells.
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Follicular cyst
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This type of cystic ovarian degeneration results in a very thick walled cyst, and must be treated with PGF.
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Luteal cyst
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Which ovarian cyst allows the cow to continue to cycle normally: Cystic CL or luteal cyst?
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Cystic CL
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Most common ovarian tumor type. How does it appear on ultrasound?
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Granulosa cell tumor
See a cluster of small cystic structures throughout the ovary. Ovary grossly enlarged. |
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On rectal palpation of a cow, an enlarged ovary is felt. What are some differential diagnoses?
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Granulosa cell tumor
Follicular/luteal cyst Abcess Hematoma |
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When a cow in heat is ultrasounded, how should a healthy uterus appear?
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Small amount of clear anechoic fluid
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These normal projections appear on a post-partum uterus as hyperechoic masses.
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Caruncles
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When doing a rectal ultrasound on a cow, what is the significance of finding a fluid-filled, non-pregnant uterus with hyperechoic, flocculant material in the lumen?
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Likely infection
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How does abnormal fluid in the uterus 3 weeks post partum affect the fertility of a cow when compared to a uterus without such fluid?
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Poor reproductive performance
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The volume of fluid in the uterus is directly correlated with...
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The amount of bacteria present
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What is pyometra?
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Pus in the uterus with a CL present
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At 24 days, what will a bovine pregnancy look like on ultrasound?
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Fluid filled vesicle, may see heart beat
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What is the significance of an embryonic vesicle with a low volume of fluid?
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Impending fetal loss--> recheck cow in 1 week so she can be bred back ASAP.
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When is it normal to see debris in the amniotic fliud when ultrasounding a pregnant bovine?
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Later in the pregnancy
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If a vet is doing an ultrasound on a cow 48 days pregnant, and he sees a small embryo with less vesicular fluid than would be expected, what should be his first course of action?
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Recheck the breeding date! May not be as far along as believed!
If fetus truly dying, then abort so cow can be bred back. |
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An abnormality is detected when doing an ultrasound on a pregnant dairy cow: There are hyperechoic bone fragments, and gas and fluid are visible where the amniotic sac had been. What could this be?
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Macerated fetus
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What structure is used to ID the sex of a bovine fetus?
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Genital tubercle
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At what point in the bovine pregnancy is it easiest to do fetal sexing by ultrasound?
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Days 60-75 (60-95 in the heifer)
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How could Doppler ultrasonography be used theoretically to predict ovulation in the cow?
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Blood vessel patterns change as ovarian structures develop and regress. Vascularity increases with impending ovulation.
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After early embryonic death in the bovine, how long can the CL persist unless lysed with PGF?
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Up to 45 days
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At what point is pregnancy typically diagnosed in the bovine with ultrasound? How does this compare with diagnosis through rectal palpation?
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28 days with U/S
35 days with palpation |
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How can ultrasound be used in the bull to improve fertility?
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Evaluate testicular masses
-Leydig cell tumors -Fibrotic foci -Hydrocele -Epididymitis Evaluate penile/preputial masses (abcess, hematoma, FB) |
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The average bovine goes into estrus somewhere in this age range.
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9-19 months
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What is the major limiting factor that determines the age of bovine estrus?
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Hypothalamic production of GnRH
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Describe the tonic center for GnRH in the hypothalamus.
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Controls the basal level of GnRH production.
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Describe the surge center for GnRH in the hypothalamus.
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Responsible for the preovulatory GnRH surge.
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In what gender does the hypothalamic surge center exist: male, female, or both?
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Female
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Is testosterone converted to estradiol in the bull brain, or is estradiol converted into testosterone?
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Testosterone converted to estradiol
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List some factors affecting the age of puberty.
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Genetics (sire scrotal circumference)
Breed Nutrition Biostimulation by male Birth season Temperature |
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A heifer will reach puperty most rapidly if she belongs to which group: purebred, hybrid, or brahman?
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Hybrid
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A heifer will take the longest to reach puberty if she belongs to which group: purebred, hybrid, or brahman?
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Brahman
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The goal is for a heifer to have her first calf at this age:
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2 years
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The average length of the bovine estrus.
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21 days
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The four stages of the bovine estrus cycle are...
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Proestrus
Estrus Metestrus Diestrus |
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During bovine metestrus, which hormone is on the rise, and which is on the decline?
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Progesterone on the rise
Estrogen on the decline |
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What is the significance of "metestrus bleeding" in the cow?
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Means the bovine was in heat and ovulated
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During this phase, the corpus luteum regresses and ovulation occurs. The dominant ovarian structure is the follicle, and the dominant hormone is estrogen.
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Follicular phase
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During this phase of the estrus cycle, the post-ovulatory follicle luteinizes. The CL grows, and then regresses. The dominant structure during this time is the CL, and the dominant hormone is progesterone.
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Luteal phase
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These follicular cells produce progesterone/testosterone.
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Thecal cells
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These follicular cells produce estradiol.
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Granulosa cells
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Prostaglandin will not work on the CL until how long after ovulation?
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5-7 days
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In the bovine there is a countercurrent exchange of PGF between these two blood vessels that serve the reproductive system.
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Uterine vein
Ovarian artery |
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What is the "short loop" that allows the veterinarian to inject prostaglandins directly into the bovine uterus for greater potency?
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Countercurrent exchange of PGF between uterine vein and ovarian artery.
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Maternal recognition of the bovine pregnancy occurs between these days of gestation.
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15-18
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What is EPSI?
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Endometrial prostaglandin synthesis inhibitor...interferes with arachadonic cascade and down regulates oxytocin receptors.
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At what point in the bovine pregnancy is attachment of the placenta to the uterus well-established?
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40 days
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How is abortion induced in the bovine before day 150?
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PGF2a
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How is abortion induced in the bovine between days 150 and 250?
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PGF2a and dexamethosone
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How is abortion/parturition induced in the bovine after day 250?
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Dexamethosone, +/- prostaglandins
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What is the pharmacologic use of GnRH in a breeding program?
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Induce ovulation/luteinization
Synchronize follicular waves |
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What is the pharmacologic use of prostaglandin in a breeding program?
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Induce luteolysis (and thus estrus/abortion/parturition)
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The most important factor for establishing reproductive success in the dairy cow.
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Heat detection
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What is the typical length of time a cow shows estrus?
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3-18 hours
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What are some signs of estrus in the bovine?
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Standing to be mounted
Walking Bellowing Drop in milk production Restlessness Frequent urination Mucus discharge |
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Is a cow more likely to display estrus behaviors in the milking parlor, or on a dirt lot? Why?
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Dirt lot (Better footing)
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Are dairy cows more likely to display estrus behaviors while they are stationary, or while they are being moved?
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During movement
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Pregnancy rate in the dairy cow is a product of
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Heat detection rate X Conception rate
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List some factors affecting how obvious the signs of estrus are in a dairy cow.
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Breed
Season (less likely to show estrus in hot weather) Lameness Ovarian pathology |
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List some automated systems for the detection of estrus in the dairy cow.
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Pedometry
Pressure sensors for mounting Temperature sensors Milk yield deviation alerts Progesterone profiles Electronic "noses" to detect pheromones Tissue or mucus impedance |
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What are the advantages of using the tail stripe system of estrus detection in a dairy herd?
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High efficiency
Inexpensive Gets producer to examine each cow |
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What are the disadvantages of using the tail stripe system of estrus detection in a dairy herd?
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AI cows that aren't truly in heat
Cows need to be checked/remarked daily |
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How long after the onset of bovine estrus does ovulation typically occur?
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24-32 hours after onset
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List some factors affecting how obvious the signs of estrus are in a dairy cow.
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Breed
Season (less likely to show estrus in hot weather) Lameness Ovarian pathology |
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List some automated systems for the detection of estrus in the dairy cow.
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Pedometry
Pressure sensors for mounting Temperature sensors Milk yield deviation alerts Progesterone profiles Electronic "noses" to detect pheromones Tissue or mucus impedance |
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What are the advantages of using the tail stripe system of estrus detection in a dairy herd?
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High efficiency
Inexpensive Gets producer to examine each cow |
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What are the disadvantages of using the tail stripe system of estrus detection in a dairy herd?
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AI cows that aren't truly in heat
Cows need to be checked/remarked daily |
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How long after the onset of bovine estrus does ovulation typically occur?
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24-32 hours after onset
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List three factors that affect the timing of AI in the bovine.
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Duration of standing activity (7+/- 5 hours)
Fertile life of egg Fertile life of frozen-thawed sperm in female reproductive tract |
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The likelihood of pregnancy is greatest when a cow is bred this long after the onset of estrus. (Range)
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4-16 hours
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Describe the AM/PM Guideline for AI in dairy cattle.
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Observe cattle in morning and evening. Cows in heat in AM should be bred at evening check. Cows in heat in PM should be bred the following morning.
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If direct observation of cows is used as the gold standard for estrus detection, how frequently should these observations take place?
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3-4 times daily, 6-8 hours apart
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The ultimate goal of the heat detection program should be to predict...
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Time of ovulatiom
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Prolongation of the first and/or second stages of parturition such that completion becomes difficult or impossible for the dam alone.
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Dystocia
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Easy, safe, natural parturition
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Eutocia
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Describes an animal in which one ova is released at a time
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Uniparous
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Describes an animal in which several ova are released at a time
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Multiparous
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Describes an animal on her first gestation
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Primiparous
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Describes an animal on her second or more gestation.
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Pluriparous
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Describes an animal who has never conceived.
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Nulliparous
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Are dystocias more common in heifers or cows?
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Heifers
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What are two major maternal causes of dystocia?
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Dam not able to push hard enough
Size of birth canal |
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In the US, what is the most common cause of beef cattle dystocia?
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Maternal-fetal disproportion
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List some reasons that maternal/fetal disproportion is such a major cause of dyctocia in US beef cattle.
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1st calf heifers aren't at mature BW (only 80-90%) at calving.
Selection for larger cattle = larger calves Bovine dam cannot control fetal size (unlike the mare) |
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What % of mature body weight should a heifer reach before she is bred?
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At least 60%
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The day after a heifer calves, she should weight this% of her mature body weight.
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85-90%
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Should pelvic area be used as a tool for selection of larger cows, or for culling of smaller cows?
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Culling the smallest cows...Otherwise you select for ever increasing mature body weight and larger calves.
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What is meant by a bull's EPD?
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Expected progeny difference--used to predict how a bull's progeny will compare to their peers with regards to birth weight, weaning weight, yearling weight, etc.
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What does it mean if a bull has "calving ease" traits?
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Low progeny borth weight but good growth characteristics.
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Give an example of a bovine breed in which the calves are large and grow rapidly, causing lots of dystocia.
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Charolais
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EPD's for a bull are calculated based on these three P's:
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Pedigree
Performance Progeny |
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When examining a bovine dystocia, you realize that the placentomes have separated from the caruncles. This means that...
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The placenta is separated, therefore the calf is dead.
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If a laboring cow will not stand, is it bettewr for her to be positioned in sternal recumbency or lateral recumbency for you to manipulate the fetus?
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Lateral recumbency, with her head downhill so you can repel uterus.
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True or false: Most calf extractions are done with the cow secured in an obstetric chute.
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False. Manipulations and prep in chute. Then tie cow up outside of chute to pull.
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List four areas in which to check a calf for viability in the birth canal.
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Pinch a foot--> retraction?
Finger in mouth--> Suckle reflex? Finger in eye socket--> blink? Feel for pulse at umbilicus or heartbeat along ribcage |
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Corneal opacity in a dead calf occurs after this length of time.
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6-12 hours post mortem
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Hair sluff develops in a dead calf after this length of time.
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48 hours post mortem
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Emphysema develops in a dead calf after this length of time.
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24 hours post mortem
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List the three possible PRESENTATIONS of a calf in the birth canal.
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Anterior
Posterior Transverse |
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The relationship of the dorsum of the calf to the pelvis of the dam is referred to as...
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Position.
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What is the normal presentation, position, and posture of a calf during delivery?
|
Anterior, dorsosacral, with both front limbs extended.
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The relationship of the limbs of a calf to his torso during parturition is referred to as...
|
Posture
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|
This term is used to describe which end of the calf is positioned to enter the birth canal first.
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Presentation
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In the event of bovine dystocia, fetal death tends to occur within this span of time.
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3-12 hours
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What is the maximal reasonable expectation for pregnancy rate in a synchronized beef herd?
|
60-70%
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|
|
What is the maximal reasonable expectation for pregnancy rate in a synchronized dairy herd?
|
30-40%
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|
|
This hormone causes regression of follicles that develop during the luteal phase.
|
Progesterone
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|
Where is endogenous progesterone produced?
|
Endometrium
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If giving 2 shots of PGF for estrus synchronization in the bovine, how far apart should they be given?
|
14 days
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|
Describe an MGA/PGF synchronization protocol in cattle.
|
MGA given po for 14 days
Remove, cows go into infertile heat. Let new CL form over 19 days from end of MGA. Give PGF. Breed 72 hours later. |
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After how long will a cow display estrus after she has been given MGA for 2 weeks?
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7-10 days
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What king of hormone analog is MGA?
|
Progestin
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|
Once a cow is given PGF, if she has a mature follicle how long on average before she goes into estrus?
|
72 hours
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|
What is the downside of a 2-shot PGF synchronization program?
|
Variability of return to estrus after luteolysis.
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|
This hormone is responsible for resetting/synchronizing the follicular wave in a herd of cows.
|
GnRH
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|
Describe a bovine synchronization protocol that uses GnRH and PGF, with timed AI.
|
Day 0: GnRH
Day 7: PGF Day 9: GnRH Day 10: TImed AI |
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|
List two sources of exogenous progesterone given to synchronize estrus in a herd of cows.
|
CIDR
MGA |
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If a cow has a CIDR in for 5 days, why would you administer 2 shots of PGF 6 hours apart once it was removed?
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To ensure that the CL is mature enough at the time of at least one PGF dose. (Takes 5-7 days to mature)
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