Flashcards in Equine Estrous Cycle Deck (38)
What type of breeders are horses?
Seasonal polyestrus (April-Oct)
What day length is required for horse breeding?
Long-day breeders (April-Oct)
When is a horse's transition period of follicular growth and regression?
How long is an estrous cycle in horses?
How many follicular waves do horses have?
One (can be major or minor) that repeatedly grows and regresses until ovulation
What hormone is high during estrus?
How long is estrus in a horse?
When does a horse ovulate?
1-2d prior to end of estrus
What are breeding options for horses?
EOD starting on 2nd day of estrus or 24-48h prior to ovulation
How long is diestrus in a horse?
Is there a metestrus in a horse?
How do you synchronize mares?
PGF2a and progestins
What age of CL does PGF2a work on?
CL >5d and mare in diestrus
How does a PGF2a dose for a horse compare to that for a cow?
Lower dose, more side effects
When does ovulation occur after PGF2a administration?
What is the purpose of mare synchronization?
AI/embryo transfer, failure of CL to regress/prolonged diestrus
What are oral progestins used in mares?
What is a non-reproductive purpose of progestin use in mares?
Suppress estrus in performance mares
How can you induce ovulation in anestrus mares?
Increase light exposure (16h/d) for 30-60d
How soon after foaling do mares return to estrus?
What is the most effective way to restart cycling or get horses to start cycling early?
Artificial light (16h/d) for 30-60d
What is gestation length in a horse?
When is a foal considered premature?
Born prior to 320d gestation
When do most horse owners want their mares to foal?
Mid-January (breed mid-Feb)
What maintains pregnancy in a horse?
Ovarian P4 early, placental P4 later
What begins stage 1 of parturition?
Fetal repositioning for parturition
What begins stage 2 of parturition?
Rupture of chorioallantois
What ends stage 2 of parturition?
Birth of foal
What is stage 3 of parturition?
Passage of placenta