Reproductive Manipulation of the Mare Flashcards
What is the mare’s repro cycle called?
Seasonally polyestrous
Are mares short or long day breeders?
Long day
When do mares reach puberty?
About 15 months
What are the 2 periods of the mare’s cycle and what is happening during them?
Anestrus -> no repro activity
Estrous -> cyclicity
Mares have a ____ day gestation with ____ days being the length of estrus
340 day gestation; 5-7 day estrus length
Mares have ___ transition periods in their cycle? When are they?
2; one before estrous and one before anestrous
When is the mare’s estrous period typically?
Mid April- mid September
What is the average length of estrous?
19-22 days (21 days= average)
What are the two stages in the estrous cycle and how long are they?
Diestrus (14-15 days)
Estrus (5-7 days)
What primary hormone is in estrus? Diestrus?
Estrus- estrogen from ovary
Diestrus - progesterone from CL
What does prostaglandin do?
Produced when there is no pregnancy and goes into anestrus (typically during winter)
Increased sunlight causes a decrease in what hormone? Which in turn causes an increase in what other hormones?
Decrease in melatonin from pineal gland, increased GnRH from hypothalamus which causes increase in LH and FSH from the pituitary gland
Ovulation occurs towards the end of ___?
Estrus
Mares cease estrus behavior ________ hours following ovulation?
24-48 hours
Compared to other livestock species, the horse has the most _______ in their repro cycle? what does this mean for horses?
Variation; means their pregnancy rates tend to be lower
You should breed your mare if you see 2/3 signs, what are these signs?
Showing heat, cervix is open, a 35 mm follicle is present
Why should we use photo stimulation on mares?
Create a longer day to breed sooner in the year, hastens onset of ovulatary season
When should we begin using photostimulation?
Before winter solstice (12/21)
When to start artificial lights and why?
Start Nov 1-Dec1 bc it takes about 60 days to get them to cycle
Traditional methods for lights is ___ days of light and ___ days of dark?
16 light and 8 dark
When is artificial light the most effective during the day?
End of day’s natural light, must be consistent
Specific time for night-interruption?
9.5 hours after onset of darkness
Name an agonist used in horses?
Deslorelin, busrelin, histrionic
Name a drug used as an agonist and what it does?
SucroMate, LH like activity makes mares ovulate within 48 hours for multiple cycles a year
HCG is a large what? used to?
Glycoprotein used to induce ovulation
What is one product often used in mares for hCG?
Chorulon
HCG is most effective in what horses?
Young mares that havent gotten this previously or the first 2-3 times in the breeding season for middle aged mares
What is the goal of using FSH in the mare?
Superovulation
What types of FSH have worked in the mare?
EFSH (purified equine FSH) and reFSH (recombinant equine FSH)
When to give a mare FSH to induce superovulation?
2x 5-7 days post ovulation with a 20 mm follicle, stop at 32-35 mm follicle
What does PGF 2 alpha do in the mare?
Short cycling, estrous synchronization, persistent CL, and termination of pregnancy
Does PGF 2 alpha work on anetrus mares?
No
Uses of progesterone, progestins, and estrogens in the mare
Suppress behavioral estrus, synchronize estrus, maintain pregnancy
How is progesterone and estrogen given to the mare?
IM or orally
