Hormonal Manipulation of Repro Function

Question 1

what does the hypothalamus make

Answer 1

GnRH
have in injectable forms

Question 2

what does the anterior pituitary make

Answer 2

LH and FSH

Question 3

what does the CL make

Answer 3

progesterone

Question 4

when is stimulation of follicular development indicated?

Answer 4

• earlier onset to breeding season
• more offspring produced per year
• production of offspring out of season
• year round milk supply (dairy goats)

Question 5

techniques of follicular development

Answer 5

• artificial/photoperiod/melatonin manipulation
• administration of GnRH or GnRH agonists
• administration of gonadotropins (FSH, eCG)
• male (whitten) effect

Question 6

when do sheep/goats breed

Answer 6

fall

Question 7

when do horses breed

Answer 7

spring

Question 8

photoperiod manipulation to stimulate follicular development

Answer 8

• increase day length (decrease duration of melatonin exposure) - stimulates reproduction in cats and horses
• decrease day length (increased duration of nighttime melatonin exposure) - stimulates reproduction in sheep and goats

Question 9

** know the difference between gonadotropins and GnRH**

Question 10

decreasing day length will stimulate reproduction in what animals?

Answer 10

sheep and goats
increase in duration of melatonin secretion (darkness) will ramp UP repro activity (opposite of horses and cats)
challenging to do on a big scale though. could theoretically give melatonin though

Question 11

increasing day length will stimulate reproduction in what animals?

Answer 11

horses

Question 12

administration of melatonin?

Answer 12

potentially in sheep and goats
not very practical for commercial use

Question 13

artificial photoperiod

Answer 13

housing mares under lights is common in the equine breeding to advance the first ovulation of the year

Question 14

what are the gonadotropins?

Answer 14

FSH: follicle stimulating hormone
eCG: equine chorionic gonadotropin

Question 15

eCG has what biological activity to ruminants?? **

Answer 15

has FSH-like biological activity when administered to ruminants!!

Question 16

where is FSH and eCG made?

Answer 16

anterior pituitary

Question 17

male/whitten effect

Answer 17

• introduce new/novel male into herd
• MOA: stimulation of GnRH pulses from hypothalamus and thus LH pulses from the anterior pituitary
  advances onset of breeding season and onset of puberty

Question 18

when is ovulation induction indicated?

Answer 18

• stimulation of timed ovulation for AI
• treatment of cystic follicles (cattle)- make them go away by getting them to luteinize
• synchronization of ovulations (cattle/horses)
• decreasing duration of estrus
• following AI in induced ovulatory species

Question 19

how can you cause induced ovulation?

Answer 19

1. GnRH or GnRH agonists
2. LH (native or rHL)
3. human chorionic gonadotropin (hCG) - hCG has LH like biological activity in ALL species
4. coital stimulation (induced ovulators) - cats stimulate and LH surge and ovulate in response to stimulation

Question 20

what is the biological equivalent of LH

Answer 20

hCG

Question 21

cystorelin/fergatyl

Answer 21

native/natural GnRH

Question 22

histrelin/deslorelin

Answer 22

synthetic GnRH

Question 23

what is hCG

Answer 23

biological equivalent of LH, human chorionic gonadotropin

Question 24

T/F: hCG bypasses the hypothalamus and pituitary and goes directly to the ovarian follicle

Answer 24

true
can use on literally any mammal

Question 25

principle of GnRH therapy

Answer 25

- administartion of GnRH induces a surge of LH release from the anterior pituitary - endogenous LH surge stimulates follicular maturation and induces ovulation

Question 26

principle of hCG therapy

Answer 26

- hCG has LH biological activity and direct efect on the ovarian follicle follicle maturation and ovulation

Question 27

cats induction of ovulation

Answer 27

- mating induces LH surge: onset in 15 minutes, peak at 4 hours - surges of LH occur after each mating - less than 50% of cats ovulate after single mating - most cats will ovulate if >2-4 matings occur - spontaneous ovulations can occur!

Question 28

coital stimulation of cats

Answer 28

- ovulation induced by stimulation of vagina and cervix - stimulation triggers LH surge - complication of vaginal cytology collection - mating to sterile male can induce ovulation

Question 29

what animals are induced ovulators?***

Answer 29

cats, camelids/llamas/alpacas

Question 30

T/F: camelids are induced ovulators

Answer 30

true

Question 31

coital stimulation of llamas***

Answer 31

- mating stimulates vagina and cervix and causes release of LH from pituitary - camelids semen also contains ovulation induction factor (nerve growth factor B); stimulates additional LH release from the anterior pituitary

Question 32

what species semen contains an ovulation induction factor?***

Answer 32

camelids (nerve growth factor B)

Question 33

superovulation?

Answer 33

- cows and mares ovulate only a single follicle each cycle (mainly cattle) - follicle development stimulated by FSH - development of other follicles is suppressed by inhibin and estradiol produced by the dominant follicle

Question 34

nerve growth factor B

Answer 34

camelid semen contains this: is an ovulation induction factor

Question 35

T/F: FSH is highly regulated in LA species

Answer 35

yes- so they don't have a litter

Question 36

what suppresses follicles?

Answer 36

inhibin and estradiol: produced by granulosa cells

Question 37

what hormone takes the follicle to go on to mature and ovulate?

Answer 37

FSH takes over after LH done

Question 38

why superovulation?

Answer 38

- embryo transfer- increase collection rate - increase rate of multiple births - enhance ovulation rate in female = increased probability of a pregnancy

Question 39

how do we induce superovulation**?

Answer 39

- administer exogenous FSH or hormone with FSH activity (eCG) to "rescue" smaller follicles in a wave (ie ruminants) - modulation of endogenous FSSH - nutrition: "flushing" in ewes

Question 40

exogenous hormone therapy

Answer 40

administration of FSH bypasses the normal negative feedback mechanisms leading to multiple ovulations

Question 41

what is the luteal phase of large animals

Answer 41

14-18 days

Question 42

when are prostaglandins effective****

Answer 42

once the corpus luteum is mature!! takes 5 days

Question 43

when is the CL susceptible to luteolytic effects of PGF?

Answer 43

until FIVE DAYS AFTER OVULATION

Question 44

what do prostaglandinds do

Answer 44

lyse the corpus luteum if given at the right time

Question 45

what is the exception to the 5 day PGF rule

Answer 45

pigs (12 days)

Question 46

what are the prostaglandins commerically available?

Answer 46

- estrumate - lutalyse

Question 47

estrous synchronization indications

Answer 47

- increased mating efficiency (AI or timed mating) - shortening of the birthing season - embryo transfer to "line up" donors and recipients

Question 48

how are progesterone and prostaglandin different

Answer 48

progesterone: steroid produced by CL prostaglandin: lil amino acid thing that LYSES a CL

Question 49

without LH, follicles can't

Answer 49

mature and ovulate

Question 50

how do you administer prostaglandin to synch up estrous cycles? ***

Answer 50

- 2 injections, 14 days apart - first dose will cause luteolysis in 50-60% of females - early return to estrus and ovulate again, form CL - second dose will synchronize most of the herd

Question 51

ovsynch program

Answer 51

- program for 15 years - cows are given GnRH (any cow with a follicle will then ovulate) - then form CL - 7 days after that, give prostaglandins to lyse CL - 2 days alter, 2nd dose of GnRH causes them to ovulate and then breed them with frozen semen goal: line up an indv cow and time ovulation without palpation/hormone therapy - pretty effective

Question 52

indications for suppressing ovarian activityq

Answer 52

- contraception: blocks follicular development and ovulation - suppression of behavioral estrus

Question 53

how do you suppress ovarian activity

Answer 53

- surgery: OVHE - medical/hormonal