Exam 2 - Hormonal Manipulation

Question 1

what techniques can you use for stimulation of follicular development

Answer 1

photoperiod/melatonin
GnRH/GnRH agonist (low dose)
FSH, eCG
Male (whitten) effect

Question 2

how does photoperiod/melatonin stimulate follicular development in cats/horses

Answer 2

cats/horses long day breeders
increase daylength = decreased melatonin = GnRH production
GnRH = FSH = follicular development

Question 3

what is eCG? when is it used? what species can it be used in?

Answer 3

equine chorionic gonadotropin
used to stimulate follicular development - it has FSH-like activity when administered to ruminants

Question 4

what techniques can you use to stimulate ovulation?

Answer 4

GnRH/GnRH agonists (medium dose)
LH
hCG
coital stimulation in induced ovulators

Question 5

what is hCG? when is it used?

Answer 5

human chorionic gonadotropin
LH-like activity in all species
direct effect on ovarian follicle = follicular maturation/ovulation

Question 6

explain the principle of superovulation

Answer 6

normally horse/cattle ovulate one dominant follicle each cycle

dominant follicle produced estrogen & inhibin to suppress non-dominant follicles

by supplementing FSH, the non-dominant follicles will grow and get ovulated

Question 7

what are the indications of superovulation

Answer 7

embryo transfer
increase rate of multiple births
enhanced ovulation rate

Question 8

what do you supplement for superovulation

Answer 8

FSH (or eCG)

Question 9

what do you use to terminate luteal activity

Answer 9

prostaglandins

Question 10

when are prostaglandins effective

Answer 10

only if there is a mature corpus luteum

Question 11

the CL is not susceptible to luteolytic effects of prostaglandins until _____

Answer 11

5 days after ovulation

Question 12

what is the easiest way to synchronize a herd

Answer 12

2 prostaglandin injections 14 days apart

could also do intravaginal progesterone for 10-14 days