The mechanism which controls the breeding cycle of cows is understood only to a limited extent. With your hand in the cow’s rectum it is possible to feel the whole of the genital organs and the changes that take place in them as the breeding cycle goes along. The mechanism that controls the goats breeding mechanism is believed to be similar.
The sexual cycle of the goat is started by the anterior lobe of the pituitary gland secreting follicle-stimulating hormones which excited the ovaries at each tip of the ‘horns of the womb’, to develop a ‘blister’ inside which one of the store of eggs in the ovary rapidly develops. This blister itself secretes estrogen which in turn produces the symptoms of oestrus or ‘heat’
The womb contracts, the cervix at the mouth of the womb relaxes and opens, the vagina is tensed and lubricated by slime. The goat becomes restless, bleats and wags its tail with a red and swollen vulva often showing signs of discharges. The goat is ready to stand to the male goat billy.
When the blister in the ovaries reaches its full size the pituitary produces luteinizing hormones which causes the blister to burst which in turn causes the mature egg to start its long winding journey down the fallopian tubes. The broken walls of the blister then grow lutein which is a kind of temporary gland that secretes progesterone. Progesterone has an opposite effect to that of oestrogen. Thus the outward symptoms of ‘heat’ subside, the vagina relaxes and dries off, the cervix closes to seal the womb and the womb then relaxes and is richly supplied by blood.
If the mating is successful the egg on its way down the fallopian tubes encounters a sperm and fertilizes and upon arriving at the womb finds its place prepared for it (by the action of the progesterone) settles down and develops. The lutein remains continuing to produces progesterone until the foetus is mature
Upon maturity of the foetus the lutein is reabsorbed and at the stimulus of the pituitary, the ovaries once more secrete estrogen which relaxes the cervix, lubricates the vagina and contracts the womb to expel the kid. When the kid is born the secretion of estrogen stops.
If the egg is not fertilized on its way down the fallopian tubes the lutein persists secreting progesterone for about 10 days after which it shrinks away and the follicle-stimulating hormone is again secreted by the pituitary gland to start the cycle all over again.