Goat Theriogenology Flashcards
Goats are ______ day breeders.
Short
What is the length of the estrous cycle in goats?
18-22 days, average of 21 days
What is the duration of estrus in goats?
24-48 hours
What can be seen at the beginning and ending of breeding season or post-partum in goats?
Increased frequency of short cycle
What are the signs of estrus in goats?
- Swollen vulva
- Mucoid discharge turning cloudy
- Seeking out and stimulating male
- Expressing immobilization reflex in response to male nudges, including serial mounting and copulations
- Tail flagging
- Plasma P4 < 1ng/mL
__________, _____________, and ____________ nutrition will all affect ovulation rate.
Breed, season and nutrition
What are ways the estrous cycle can be manipulated in goats?
- Photoperiodic treatments
- Male effect
- Dormitory effect
- Adapted nutrition
- Hormonal treatments
- Combination of above
Photoperiodic treatments
- Begin with long days to prepare for stimulatory effects of short days or else they become photo-refractory
- Decrease day = trigger melatonin release from pineal gland
Male effect (>sheep)
- Introducing a buck into a group of transitional period does to activate LH secretion and induce ovulation
- Epididectomized/vasectomized males or androgenized females
- 1 tears for 40-50 females
- No sight sound or smell for 30 days, then abruptly introduce male - 48hrs for effect
- Silent ovulation since no P4 priming = no response to E2
Flushing females before breeding
- Increased energy before or early in breeding season = increased ovulation rate = increased twinning rate
- 1lb high-energy supplement (corn, oats, barely) per day 2-3 weeks before breeding
The use of hormone treatments requires
the goat to be cycling
Synthetic progesteron/progestins in goats
- Sponges intravaginal
- CIDR (330mg) progesterone***
- Melengesterol acetate in feed
- 5-14 days, estrus shown in 24-96 hours after withdrawl
Ovulation induction in goats
- eCG/PMSG (equine chorionic gonadotrpin/ pregnant mare serum gonadotripin) - acts directly on OVARY to stimulate ovulation (FSH-like), longer half life (36hr)
- GnRH agonists - act on ANTERIOR PITUITARY to stimulate LH/FSH activity, short half-life (0.5-1hr)
Describe the process of ovulation induction during the seasonal transition period.
- Progestin for >14d (18-21) + PG600 on the day of or 24-48 hours before progestin removal
- Ram/buck effect in late transition as well as progestin tx similar to early transition
- Photoperiod manipulation (begin during summer)
Describe the process of ovulation induction outside of the breeding season.
- Progestin > 14d (18-21) + PG600 the day of or 24-48hr before progestin removal
- Artificial lighting programs: minimic long days ~60d followed by short days for 60d or natural light