[Nutrition and fertility in agricultural domestic animals]

This paper deals with the reduction of fertility in cattle and pigs due to increased production. Special attention has been paid to the negative energy and protein balances during the first weeks post partum. It has been questioned which organs and organ systems become affected by the changes in these balances. For that study, the animal model of the overconditioned cow ante partum has been developed and used. The paper is dealing with possible effects on the hypothalamic-hypophyseal (HH) system and LH release, on the ovaries with secretion of steroids and release of properly matured oocytes, on the uterus as milieu for the embryo and on the immune system with leucocytes that play a role in follicle development and ovulation. The preliminary results of the first experiments open the discussion whether the reduction in fertility in this model is the consequence of the direct effect of glucose and insulin on the HH system and ovaries or of the indirect toxic effect of the non-esterified fatty acids, resulting from a temporary decrease of insulin, on granulosa cells and gametes.