Negative energy balance

Abstract

n early lactation the cow is in negative energy balance because the energy needs for the production of colostrum, milk and maintenance requirements, Exceeds the amount of energy supplied by the dry matter intake, which is decreased in this period. In the adaptation phase, the events supporting the homeostatic metabolic contribution to lactation, ensuring the provision of energy for milk production. The negative energy balance leads to metabolic changes such as weight loss, mobilization of fat and muscle, hypoinsulinemia and hypoglycemia due to low IMS, high concentrations of growth hormone, suppression of the growth factor insulin-like, elevation of nonesterified fatty acid and β-hydroxybutyrate. All these changes in energy balance lead effects on reproduction, for influence in both the central nervous system (hypothalamus, pituitary), by inhibiting the synthesis and release of GnRH, LH and FSH, as in the ovary by influencing the synthesis of steroids the regulation of follicular growth, IGF system. These effects can induce changes in follicular dynamics, in follicle size and quality of the oocyte. Further understanding the metabolic changes that occur in the BEN, it is possible to establish a more efficient one body condition score ideal for each stage of production cycle of cows, thus minimizing loss in reproductive efficiency.