Anoestrus in Dairy Cows: Causes, Prevalence and Clinical Forms

This article reviews some of the recent advances in veterinary research regarding the causes, prevalence and clinical forms of pathological anoestrus in dairy cows. It is one of the few components responsible for occurrence of postpartum infertility in cattle, expressed in four clinical forms: silent heat, cystic ovarian disease, ovarian afunction and corpus luteum pseudograviditatis. The prevalence of these four forms in different herds is dependent on the managerial, environmental and nutritional status of the farm. Anything, regardless of its nature, that impedes the physiological mechanism involved in oestrus expression is liable to cause anoestrus. Nutrition (energy deficiency), interacted with other factors, is the major cause of this phenomenon (anoestrus). It has direct control of the postpartum anoestrus by negatively affecting the endocrine pathways responsible for proper functioning of the reproductive system through the blockage of pulsatile release of gonadotropin‐releasing hormone in the hypothalamus. Lack of proper training by the stockman substantially contributes to silent heat occurrence. Numerous attempts have been made to prevent or treat pathological anoestrus with exogenous hormones, or nonhormonal remedies like uterine palpation and infusion of Lugol's solution, all of which have produced variable but positive results. Specific treatment for each one of the four clinical forms is briefly outlined.