08 Ruminants and Mares Flashcards
Ruminant Estrous Cycle
Whole estrous cycle is 21 days (18-24) Estrus- 12 hrs Metestrus- day 5-6 Diestrus- day 17-18 Proestrus- day 21
Estrous Cycle
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Ruminant Stages of Parturition
Stage 1- uterus small contractions, cervix dilates, isolation restless tail raised, uncomfortable
About 2-6 hrs
Uterine membranes appear between stage 1 and 2
Stage 2- Active Labor
active abdominal contractions, calf in birth canal, calf is born
About 15-90 mins, >90mins is a dystocia
Stage 3- Expulsion of Fetal Membranes
Normal: 2-12hrs
Retained: 12-24hrs
Mare type of breeder and seasons
Mare is long day breeder Vernal transition Active cycling Autumnal transition Winter Anestrus
Vernal transition
Inc daylight so decrease melatonin which causes inc GnRH and inc FSH and LH and inc estrogen and progesterone
Have several follicular waves being produced but not enough LH so no ovulation of a follicle
Active cycling
Once ovulation of a follicle begins
follicle–>corpus hemmoragicum–> corpus luteum
Universal Birth date
January 1st
physiological breeding season: April-September
operational breeding season: Feb-July
do this by using artificial daylight to have first ovulation on Feb 15
Estrus behaviors
Winking, urinating, tail end to stallion
Mare ovary difference
Ovulation fossa
Cortex on inside
Medulla on outside
Autumnal Transtion
shorter days= dec light= inc melatonin= dec GnRH=dec FSH and LH and dec estrogen and progesterone
will form very large follicles but do not have enough LH to ovulate
Winter Anestrus
inactive ovary
adrenal can still make estrogen
so behavior is unpredictable
Progesterone release in mare
first 1/3 of pregnancy by ovarian progesterone
last 2/3 is by fetoplacenta
Oviductal Events
Infundibulum covers ovulation fossa
Isthmus
Ampulla for sperm passage
Amupullary-isthmic junction where fertilization occurs
When to detect pregnancy in mare?
Day 13-15 to see if their are twins
Mare embryo must move around lumen and body of uterus so PGF2a is not released
Endometrial cups
day 37 of gestation
secrete equine chorionic gonadotropin (ECG) which causes secondary CL to form
accessory CL helps maintain preg until placenta progesterone production begins around day 120
Length of gestation in mare
day 320-360
Stages of Parturition-Mare
Stage 1: 1-4 hrs
foal on its back and works with contracting uterus to turn itself over. Want foal front legs and head out
Stage 2: 30-60min
Very intense uterine contractions. Want uterus out as fast as possible
Stage 3:1-3hrs
placental expulsion
>3hrs is retained this is an emergency
Ruminant #ovulations/cycle
1 (can be 2 or more in dairy cows)
Life span of CL Ruminant
14-17days
Ruminant entry of ova into uterus
About 5 days
Ruminant gestation length
9 months
Ruminant source of progesterone
CL until day 150-250 and then placenta takes over
Mare embryo transport into uterus
Day 5.5-6 via the oviductal papilla
