L6: Factors modulating female cyclicity

Question 1

what are some external factors that influence the timing of cyclicity in the female

Answer 1

• photoperiod/season
• lactation
• social factors/pheromones
• nutrition
• age

Question 2

when does the estrus cycle (heat) start in mares

Answer 2

5-8 days after foaling, ovulation occurs 10 days postpartum

Question 3

mares are ____ breeders with gestation periods of about _____ days

Answer 3

seasonal
330-345 days

Question 4

year round breeders such as the ______ and _____ undergo polyestrous

Answer 4

cow and sow

Question 5

what animals are seasonal breeders (seasonally polyestrous)

Answer 5

horse, cat, sheep, goat
- several estrous cycles followed by an anestrous

Question 6

what animals are monoestrus (have one yearly estrus cycle followed by prolonged anestrous)

Answer 6

dog, wolf, bear

Question 7

Anestrus is characterizied by low _____ released and low _____ activity

Answer 7

low estrogen release
low reproductive activity

Question 8

what months do mares breed

long day breeders

Answer 8

March - October

Question 9

what is the primary controller of reproductive cycles

Answer 9

light

Question 10

light sensitizes the HPG axis by releasing _____

Answer 10

GnRH

Question 11

the _____ gland releases melatonin in response to ________

Answer 11

pineal
darkness

Question 12

light stimulates the reina and activates the ______ through the ___________

Answer 12

hypothalamic suprachiasmatic nucleus (SCN) through the retinal hypothalamnic tract (RHT)

Question 13

Suprachiasmatic nucleus inhibition of the _____ gland decreases melatonin to alter….

Answer 13

pineal gland
to alter: day/night acitivity, seasonal breeding activity

Question 14

what is the effect of persistent corpus luteum in mares

Answer 14

can’t go into estrus = no ovulation

Question 15

what is the treatment for persistent corpus luteum in mares

Answer 15

Administration of PGF2alpha

estrus should occur 5-7 days following

Question 16

mares that foal early (january) can be at risk for..

Answer 16

anestrus due to short photoperiods

Question 17

treatment options for anestrus in mares that foaled early

Answer 17

• artificial manipulation of photoperiod
• breed on foal heat

Question 18

____ born lambs come into puberty at a yougner age than fall-born

Answer 18

spring

Question 19

gilts in small herds enter puberty _____ than gilts in large herds

Answer 19

later

Question 20

suckling inhibits _____ releases which releases _______

Answer 20

dopamine, prolactin

Question 21

during lactation, sows undergo complete inhibition of ______

Answer 21

ovulation
suckling inhibits dopamine release

Question 22

during lactation, when dopamine is suppressed, lactotrophs release _______ which inhibits ______ syntehsis

Answer 22

prolactin, GnRH

Question 23

in dogs and rodents, Prolactin supports the maintenance of _____

Answer 23

CL

Question 24

higher body weight and higher % body fat are associated w/ _____ reproductive activity

Answer 24

greater

Question 25

Leptin targets _____ neurons in the hypothalamus, which affects the relelase of ____ from the preoptic nucleus

Answer 25

Kisspeptin
GnRH