seasonal ovulators and poultry reproduction

sheep are

short day breeders so they enter estrous during fall and winter

horses are

long day breeders so they enter estrous during spring and summer

anestrus pathway (sheep spring or summer)

higher amount of light causing firing of retinal nerves at high frequency and excitatory neurons stimulate inhibitory neurons in the pineal gland to release inhibitory neurotransmitters which prevent pinealocytes from synthesizing and release a small amount of melatonin that causes release of GnRH

low melatonin in sheep

activates the RFRP neuron (increase RFRP-3) causing low kiss neuron-10 which causes low GnRH, FSH, and LH

estrus pathway for horses (summer and spring)

higher amounts of light stimulates retinal nerves which signals the suprachiasmatic nucleus which excites superior cervical ganglion which excites the pineal gland so pinealoyctes release a small amount of melatonin increasing RFRP-3 neuron stimulating kiss-10 neurons and increasing GnRH, FSH, and LH

in general female poultry reproductive anatomy

only left side develops, no gestation and hens are seasonal, photoperiod causes ovulation

chalaza

part of the egg that holds the yolk in place

yolk

part of the egg, it has layers to help supply nutrients

blastodisc

attached to the yolk, holds genetic information

the ovary

continous follicle growth, ovulation every 24 hrs and no corpus luteum

PGF2a

positions the egg in a way that is easier to lay

estrogen

helps maintain the function of the reproductive tract

LH and FSH

same function as other species

progesterone

regulates ovulation, egg-laying sequences, and embryonic development

infundibulum

catches ovulated yolks, fertilization occurs here because there are no layers

magnum

comparative to ampulla, larger part of tract, thick albumen and chalazae made here

isthmus

smaller part of tract, inner and outer shell membranes form

shell gland

eggs spend majority of time here (20 hrs), deposits calcium carbonate to form shell and adds pigament

vagina

bloom/cuticle formed here and oviposition

cloaca

reproduction and excretion, males have them too

male reproductive anatomy

internal testes (1% of BW), no true penis instead bird phalluses, and no epipidydimis or accessory sex glands

sperms stored in the female tract

for up to 28 days and viable for 6 days in the sperm storage tubule

sperm storage tubule

all sperm released at once ~25000 sperm/tubule