Suplementação proteica de vacas leiteiras F1 Holandês x Zebu manejadas em pastos diferidos de capim-braquiária

Abstract

The objective of this study was to evaluate different levels of protein supplementation on the productive performance and milk composition of F1 Holstein x Zebu cows, kept in pasture deferred from Brachiaria decumbens. The design was completely randomized with the following treatments: PDSPCA, deferred pasture without protein and at milking feed supply (24.8% PB); PDCPCB, deferred pasture plus protein and at milking receiving feed (17.6% PB); PDCPCA, deferred pasture plus protein and at milking receiving feed (24.8% CP) and; SMCA only corn silage as bulky and in milking receiving ration (24.8% PB). It was evaluated the average daily milk yield (kg/cows.days) with and without correction for fat and body weight change score of cows, calf weight (kg) composition of milk - fat, protein, lactose, dry extract defatted, total dry extract, CCS and N-ureic. The milk production was higher in cows that received only corn silage as bulky for both the average production and the corrected production for the fat content. The grazing cows in the pasture without supplementation influenced a linear production decrease and decrease of weight and score of the animals. Cows fed exclusively with silage gained weight in relation to the beginning of the experiment. The treatments used did not influence the calves' weight. The F1 Holstein Zebu cows fed on deferred pasture supplemented with protein maintains average production per day of 11.76 kg of normal composition milk, without major changes in body weight and body condition score. The non-complementation of deferred pasture with protein causes a decline in milk production and accentuates the weight loss of cows.