species of choice - equine

estrus length

2-12 (7) days

estrous cycle length

15-26 (21) days

fertile life of oocyte

6-8 hrs

time of ovulation

48 hrs (1-2 days before end of estrus)

time of AI

2nd day of estrus, every two days for remaining estrus period

1st cleavage

2.4-4 days

gestation length

320-380 (340 days)

original CL (progesterone)

present until day 180

secondary CLs (progesterone)

present until day 40-120/180

placental progesterone/endometrial cups

present starting day 70

total motility threshold

greater than or equal to 65%

forward motility threshold

greater than or equal to 35%

fertile life of sperm

72-120 hours

stage 1 parturition

uterine contractions, cervical dilation, 1-4 hours (chorio-alantois may rupture)

stage 2 parturition

entrances of fetus into birth canal, oxytocin release, abdominal press, amnion rupture, 12-30 minutes (until expulsion of fetus)

dystocia

uterine torsion, large fetus, poor positioning/presentation

stage 3

expulsion of fetal membranes, less than three hours

induction

not recommended, long gestation; 20-60 IU of oxytocin after day 320 if needed