hanisms associated with anestrus involve
blockage of the GnRH “pulse generator” in the hypothalamus, but other pathways also
must be involved because bypassing the pulse generator is not an effective treatment for all
cows. The primary cause of anestrus probably is different for different stages of anestrus.
The mediating mechanisms for anestrus are not involved with prolactin, oxytocin, the
adrenal or direct neural input from the mammary gland but are at least partially involved
with blood glucose and the endogenous opioid peptide system. Management options to
decrease the impact of anestrus and infertility include: 1) restrict breeding season to 545 d;
2) manage nutrition so body condition score is 5 to 7 before calving; 3) minimize effects of
dystocia and stimulate estrous activity with a sterile bull and estrous synchronization; and
4) judicious use of complete, partial or short-term weaning.