Reproduction Flashcards
What organs are involved in reproductive activity?
Hypothalamus
Pineal Gland
Pituitary Gland (anterior lobe)
What are some important reproductive hormones in Ewes?
GnRH - stimulated by melatonin, produced by hypothalamus, goes to pituitary gland
LH - stimulated by GnRH, travels to ovaries
E2 - stimulated by LH and FSH, produced by ovaries, travels to brain to start Estrus
Progesterone - secreted by CL, has negative feedback loop on GnRH and LH
Prostaglandin - produced by uterus, travels to ovaries, leads to regression of CL
What are the seasonal Polyestrous cycles?
- Long Day Breeders (Spring breeders, horses, etc.)
- Short Day Breeders (Autumn breeders, sheep, goats, etc.)
Does daylight affect testosterone in Rams?
Yes
How long does estrous last?
17 days
How long does estrus last?
15-45 hours
What sort of toxicity is at highest risk for pregnant ewes (especially those with multiples)?
Pregnancy Toxemia / Ketosis
What trimester does majority fetal growth take place?
third trimester - 70% of fetal growth happens here
Why do we pregnancy test?
lowers cost/increases economic efficiency by reducing the amount of open ewes being fed pregnancy rations, as well as allowing for early culling of open ewes
What are breeding marks?
the use of a pigment placed on a rams chest, where when he mounts an ewe he leaves behind marker and shows the rancher the ewe has been mounted and by which ram.
What are the pros and cons of using breeding marks for pregnancy testing?
Pros: early detection, inexpensive
Cons: not 100% accurate / guaranteed
What is udder palpation?
a form of pregnancy testing where the ewe is ‘bagged’ to test mammary development 2 weeks prior to lambing to see if she is pregnant.
What are the pros and cons of udder palpation?
Pros: the only input is time and labor and is fairly accurate
Cons: variation in udder size/development, as well as being a late term pregnancy detection so not much money is saved
What is ultrasonography used for?
a form of pregnancy checking that can be done 45-70 days after ram removal to see if the ewe is pregnant
what are the pros and cons of using ultrasonography for pregnancy testing?
Pros: very accurate (98%) and can save money on feed
Cons: expensive and doesnt count fetus with decent accuracy
What are blood tests used for?
a form of pregnancy checking where blood is drawn from an ewe 30 days after ram removal. The test measures the amount of pregnancy protein present.
What are the pros and cons of using blood tests as pregnancy checks?
Pros: 99% accuracy, saves money on feed, and not much training required
Cons: costly and determining amount of fetuses isnt possible
how long are ewe pregnancies and how soon after lambing can they be bred again?
144-150 days and can be bred again 30 days after lambing
How long does the ram spermatogenesis cycle take?
6-8 weeks
what are the effects of temperature on sperm production?
optimal sperm temperature is 96 degrees F, where the typical ram body temp is 101-104. The higher the temperature of the testes the lower the sperm production (even a 0.5 temp variation lowers the production)
What are some reproductive behaviors of ewes during estrus?
- tail-fanning
- standing still
- head turning/looking at ram
What are some reproductive behaviors of rams during estrus?
- sniffing
- flehman
- nudging ewes with head/pawing at ewes
What are some things to consider towards ram care during estrus?
additional feed to accommodate the increase travel distance and movement as well as assuring the ram doesnt get overwhelmed by the amount of ewes (only having the max amount of ewes per ram)
What are maiden ewes?
ewes that are younger and have less experience with estrus; are ‘shy’
how to ensure mating of maiden ewes?
- utilize active/experienced rams
- mate maiden ewes and mature ewes separately
- increase rams present
Which feed / feeding strategy is most efficient for supplemental feed during breeding season?
using meadow hay or alfalfa to supplement
What does a typical BSE measure?
- physical evaluation
- scrotal evaluation
- semen testing
What are the minimum satisfactory percentages for motility and morphology in a rams BSE?
motility - 30%
morphology - 50%
What is a part of the physical evaluation section of the BSE?
- teeth check
- body condition scoring
- recording presence of any disease or genital defects/abnormalities
What three things do we measure with BSE semen testing?
- semen motility
- semen morphology
- volume and color
Why do we synchronize estrus?
shortens the lambing window and allows for lambs and ewes to be managed more uniformly
how do we synchronize estrus?
- the ‘Ram Effect”
- light manipulation
- hormonal manipulation
What is the ‘Ram Effect’
introducing a vasectomised ram to a group of ewes and this leads to the initiation of cycling and synchronization
What is flushing?
feeding ewes an increased plain of nutrition 2-3 weeks before breeding and 2-3 weeks after initial breeding to increase ovulation and lambing rates
How does ewe body condition relate to lamb weight?
The better the body condition score the heavier and healthier the lamb
