Lactation
Lactation is a period of milk production. The organ that produces the milk is the mammary gland. Milk letdown results from sensory nerves in the teat or other stimuli such as kid crying. The hormone responsible for milk letdown is oxytocin, which causes smooth muscle cells inside the mammary gland to contract and move the milk through the duct system inside the gland. Milk letdown can be blocked temporarily if the animal is frightened.
Following kidding, there is a period where the female does not undergo estrous cycling during early lactation and this is referred to as lactational anestrous. There has to be time to allow for uterine involution -- or a return to non-pregnant size/repair of endometrium -- as well as to prevent a new pregnancy before the young are weaned.
Delays to estrus:
-Poor nutrition during gestation or lactation, Disease, Metabolic disorders, Uterine infections, Retained placentas, Dystocia
