Perfil mineral de vacas mestiças Girolanda no período de transição em sistema semi-intensivo em duas estações do ano

Abstract

The metabolic profile of dairy cows in the transition period during summer and winter was evaluated. Were used 31 crossbred Holstein/Gir cows at each season, totaling 62 cows. During summer they remained in pasture with supplementation of corn silage and concentrate and in the winter, corn silage and concentrate was offered to furnish the nutritional requirements. A total of 11 blood samples from each animal were taken according to the following protocol: four collections weekly antepartum, at birth and at 2, 5, 10, 15, 21 and 30 days postpartum. Concentrations of calcium, phosphorus and magnesium were evaluated. All analytes varied according to the physiological status. The average concentrations of calcium and magnesium were higher in summer than in winter. In both seasons, the lowest mean calcium concentrations occurred near calving, and 75% of the animals in winter and 35.48% of the animals in the summer were hypocalcemic. Only on the tenth day postpartum, the calcium concentrations returned to levels of prepartum, demonstrating that this time is necessary for the adaptation of the new condition of lactating. Magnesium concentrations were lower postpartum than prepartum in both seasons, demonstrating the need for this mineral for the production of milk. The average concentrations of magnesium remained always within the reference values for the species, but 19% of the animals at two days postpartum in winter and 7% of the animals at 10 days postpartum in summer had concentrations below these limits. Phosphorus concentrations suffered large variation along the peri-partum, but always at high levels, with 49.8% of the animals in winter and 37.3% in summer had phosphorus levels above the reference range of the species.