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
What are the AI options for goats?
- Fresh semen intravaginal, cervical, or transcervical intrauterine
- Laparoscopic intrauterine insemination for frozen semen
How many cervical rings does a doe have?
4
Estrous cycle synchronization for AI in goats
GnRH —> 7 days —-> PGF2a —> 2 days —> GnRH —-> 16hr —-> transcervical AI
Intersex conditons in goats
Usually in dairy goats –> linked to the polled gene
Generally - phenotypic females that tend to act like males after puberty = male gonads inside
Describe false pregnancy in goats.
- Cloud burst or hydrometra
- Dairy goats due to CL retention
- Cause unknown
- Abdominal enlargement, acts like normal pregnancy
- Fluid in uterus - no fetus or placentomes
- Tx = prostaglandins, sometimes spontaneously expel themselves
What is the gestation length of a goat?
Average 150 days
Are goats CL dependent or not?
Goats are CL dependent = needs CL for the entire duration of the pregnancy
What are the important abortifacient viruses in small ruminants?
Border disease
Bluetongue virus
Caprine Herpes Virus 1
Border disease virus infection in goats occurs when ______________. It is transmitted_________ and abortion can occur ______ of gestation. Fetal infection after ______ results in normal lambs with antibodies.
Border disease virus infection in goats occurs when a persistently infected animal is introduced. It is transmitted venereally from shedding rams and abortion can occur at any stage of gestation. Fetal infection after 85 days results in normal lambs with antibodies.
