08 Ruminants and Mares

Question 1

Ruminant Estrous Cycle

Answer 1

Whole estrous cycle is 21 days (18-24)
Estrus- 12 hrs
Metestrus- day 5-6
Diestrus- day 17-18
Proestrus- day 21

Question 2

Estrous Cycle

Answer 2

INSERT IMAGE / GRAPH

Question 3

Ruminant Stages of Parturition

Answer 3

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

Question 4

Mare type of breeder and seasons

Answer 4

Mare is long day breeder
Vernal transition
Active cycling
Autumnal transition
Winter Anestrus

Question 5

Vernal transition

Answer 5

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

Question 6

Active cycling

Answer 6

Once ovulation of a follicle begins

follicle–>corpus hemmoragicum–> corpus luteum

Question 7

Universal Birth date

Answer 7

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

Question 8

Estrus behaviors

Answer 8

Winking, urinating, tail end to stallion

Question 9

Mare ovary difference

Answer 9

Ovulation fossa
Cortex on inside
Medulla on outside

Question 10

Autumnal Transtion

Answer 10

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

Question 11

Winter Anestrus

Answer 11

inactive ovary
adrenal can still make estrogen
so behavior is unpredictable

Question 12

Progesterone release in mare

Answer 12

first 1/3 of pregnancy by ovarian progesterone

last 2/3 is by fetoplacenta

Question 13

Oviductal Events

Answer 13

Infundibulum covers ovulation fossa
Isthmus
Ampulla for sperm passage
Amupullary-isthmic junction where fertilization occurs

Question 14

When to detect pregnancy in mare?

Answer 14

Day 13-15 to see if their are twins

Mare embryo must move around lumen and body of uterus so PGF2a is not released

Question 15

Endometrial cups

Answer 15

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

Question 16

Length of gestation in mare

Answer 16

day 320-360

Question 17

Stages of Parturition-Mare

Answer 17

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

Question 18

Ruminant #ovulations/cycle

Answer 18

1 (can be 2 or more in dairy cows)

Question 19

Life span of CL Ruminant

Answer 19

14-17days

Question 20

Ruminant entry of ova into uterus

Answer 20

About 5 days

Question 21

Ruminant gestation length

Answer 21

9 months

Question 22

Ruminant source of progesterone

Answer 22

CL until day 150-250 and then placenta takes over

Question 23

Mare embryo transport into uterus

Answer 23

Day 5.5-6 via the oviductal papilla