BIOCHEMICAL ENERGY INDICATORS DURING POST-PARTUM PERIOD IN HIGH-YIELDING DAIRY COWS THEIR RELATION WITH MILK COMPOSITION

Abstract

ilk synthesis is a challenge for energy metabolism lactation process requires a great quantity of gluconeogenic precursors for lactose synthesis. In early lactation period cows reduce dry matter ingestion and this situation lead to a negative energy balance (BEN) which is characterized by mobilization of lipid reserves. main objective of this work was to monitor biochemical energy indicators during postpartum period in high-yielding dairy cows and to evaluate possible relations of those metabolites with milk composition. The study was done with 110 multiparous Holstein Friesian dairy cows fed forage, hay, silage, concentrate and mineral supplement. Balancing of the diet was made through commercial software. The postpartum period that was evaluated by groups corresponded to 2, 5, 8 and 11 weeks of lactation, the same group and number of animals were evaluated during the winter and the summer. In the each period blood and milk samples were collected from seven animals group in five different herds. Non-esterified fatty acids (NEFA), beta-hydroxibutirate (BHB), glucose, triglycerydes and cholesterol were determined through colorimetric technique. Milk composition was determined by near infrared spectrophotometry (NIRS). Statistical analyses included correlation test, analysis of variance and Tukey´s means test. It was concluded that there is no statistical association between milk composition and energetic indicators. KEY-WORDS: Dairy cows, energetic metabolism, energy balance, milk composition.