Ruminant Reproduction- Lecture 13 & 14

Question 1

Broad ligaments

Answer 1

Mesometrium. Mesosalpinx. Mesovarium.

Question 2

Tubular components of the female reproductive system

Answer 2

Vagina, cervix, uterus, oviduct.

Question 3

The estrous cycle

Answer 3

Period of reproductive cyclicity, which only ceases during pregnancy. Estrous cycle consists of two major phases: follicular and luteal.

Question 4

Phases of the cycle

Answer 4

Estrus/heat –> Metestrus –> Diestrus –> Proestrus –> Estrus/heat

Question 5

Fig 8.1

Answer 5

image

Question 6

Luteolysis

Answer 6

In the cow, ewe, and goat: luteolysis is dependent on the presence of the uterus (not in primates). A local effect in ruminants (uterine horn and its ipsilateral ovary). PGF2a enters ovarian artery from utero-ovarian vein via a counter-current exchange mechanism; PGF2a gets to the ovarian artery without entering general circulation.

Question 7

Prostaglandin

Answer 7

produced by the uterus on day 15-17 travels to the ovary and lyses the CL (if the cow is not pregnant).

Question 8

Cow repro stats

Answer 8

Age of puberty: 9-11 mon.
Estrous cycle: 21 days.
Ovulation time from estrus onset: 24-30 hrs.
CL life span: 14-17 days.
Source of progesterone: CL until 150-250 days.
Entry of ova into uterus: 5 days.

Question 9

Sheep and goat anatomy

Answer 9

Miniature cow.
Cannot be palpated via rectum.
Can be palpated vaginally at parturition.

Question 10

Doe and ewe anatomy

Answer 10

Cervical rings:
Ewe- 4 to 6 rings, tortuous (AI difficult).
Doe- 4 to 6 rings, aligned.

Question 11

Seasonality

Answer 11

Reproductive activity in caprin and ovine are regulated by seasonal variation. Changes in day length.

Question 12

Short day breeders

Answer 12

Increased light –> increased firing of retinal nerves –> increased sup. cervical ganglion –> inhibit pineal gland –> decrease melatonin –> decrease GnRH –> decrease FSH and LH –> anestrus.

Question 13

Ewe repro stats

Answer 13

Age of puberty: 6-9 mon.
Estrous cycle: 17 days.
Ovulation time from onset of estrus: 24-30 hrs.
CL life span: 14 days.
Gestation length: 148 days.
Source of progesterone: CL until 55-60 days.

Question 14

Doe repro stats

Answer 14

Age of puberty: 6-8 mon.
Estrous cycle: 21 days.
Ovulation time from onset of estrus: 30-36 hrs.
CL life span: 15-17 days.
Source of progesterone: CL.

Question 15

Periods of pregnancy

Answer 15

zygote, embryo (1st division), period of embryo organogenesis (6 weeks).

Question 16

IFNT/ interferon tau

Answer 16

The pregnancy recognition hormone in sheep and other ruminants. Acts to silence expression of estrogen receptor alpha and, in turn, oxytocin receptor. To prevent luteolytic mechanisms that require oxytocin from CL and pituitary.

Question 17

Placentation

Answer 17

Epitheliochorial- degree of invasion.
Cotyledonary- shape.
Villous- interdigitation.
Nondeciduous- maternal loss of endometrium.
Implantation in cow at 28-33 days.

Question 18

Placentomes

Answer 18

(Caruncles+ Cotyledons) develop and get larger as pregnancy progresses.
Caruncle- maternal.
Cotyledon- fetal.
Connected by villi.
Placenta regulates exchange of nutrients and waste products from fetus to dam.

Question 19

Fetal stress. Fig 14-14

Answer 19

image

Question 20

Stage 1 of parturition

Answer 20

Uterus begins to make small contractions.
Cervix dilates.
Outward signs: isolation, restless, tail raised, uncomfortable.
May not see any signs.
Lasts 2-6 hrs.

Question 21

Uterine membranes appear

Answer 21

End of stage 1 or beginning of stage 2 of parturition.
1st allantoic fluid: watery brown or yellow fluid. 2nd amniotic fluid: thick, clear-white fluid. Average interval between rupture of 1st and 2nd is 15 min.

Question 22

Stage 2 of parturition

Answer 22

Active abdominal contractions.
Calf enters the birth canal.
Cow continues to dilate.
Calf is born.
Lasts for 15-90 min.

Question 23

Stage 3 of parturition

Answer 23

Expulsion of the fetal membranes.
Normally done within 2-12 hours.
Retained takes up to 12-24 hours.