L6: Factors modulating female cyclicity Flashcards
what are some external factors that influence the timing of cyclicity in the female
- photoperiod/season
- lactation
- social factors/pheromones
- nutrition
- age
when does the estrus cycle (heat) start in mares
5-8 days after foaling, ovulation occurs 10 days postpartum
mares are ____ breeders with gestation periods of about _____ days
seasonal
330-345 days
year round breeders such as the ______ and _____ undergo polyestrous
cow and sow
what animals are seasonal breeders (seasonally polyestrous)
horse, cat, sheep, goat
- several estrous cycles followed by an anestrous
what animals are monoestrus (have one yearly estrus cycle followed by prolonged anestrous)
dog, wolf, bear
Anestrus is characterizied by low _____ released and low _____ activity
low estrogen release
low reproductive activity
what months do mares breed
long day breeders
March - October
what is the primary controller of reproductive cycles
light
light sensitizes the HPG axis by releasing _____
GnRH
the _____ gland releases melatonin in response to ________
pineal
darkness
light stimulates the reina and activates the ______ through the ___________
hypothalamic suprachiasmatic nucleus (SCN) through the retinal hypothalamnic tract (RHT)
Suprachiasmatic nucleus inhibition of the _____ gland decreases melatonin to alter….
pineal gland
to alter: day/night acitivity, seasonal breeding activity
what is the effect of persistent corpus luteum in mares
can’t go into estrus = no ovulation
what is the treatment for persistent corpus luteum in mares
Administration of PGF2alpha
estrus should occur 5-7 days following
mares that foal early (january) can be at risk for..
anestrus due to short photoperiods
treatment options for anestrus in mares that foaled early
- artificial manipulation of photoperiod
- breed on foal heat
____ born lambs come into puberty at a yougner age than fall-born
spring
gilts in small herds enter puberty _____ than gilts in large herds
later
suckling inhibits _____ releases which releases _______
dopamine, prolactin
during lactation, sows undergo complete inhibition of ______
ovulation
suckling inhibits dopamine release
during lactation, when dopamine is suppressed, lactotrophs release _______ which inhibits ______ syntehsis
prolactin, GnRH
in dogs and rodents, Prolactin supports the maintenance of _____
CL
higher body weight and higher % body fat are associated w/ _____ reproductive activity
greater
Leptin targets _____ neurons in the hypothalamus, which affects the relelase of ____ from the preoptic nucleus
Kisspeptin
GnRH
