Effect of protein sources on the diet of cows grazing on milk quality

This study objective was evaluate four different protein sources use effect in dairy cows feeding kept under Panicum maximum cv. Tanzania and the milk composition. The experiment was carried out between February and May 2016, at the Paulista Agribusiness Agency (APTA), in the city of Colina /Sao Paulo/ Brazil. Twelve crossbred Holstein × Zebu cows with 20 milk liters/ day average production, between the 45th and 90th lactation days, grouped into four groups of three animals and distributed in a 4 x 4 Latin square experimental design, with four replications. Where, each group received after the morning and afternoon milks, concentrated ration with 12% CP, being distinguished only the protein source, which were; Soybean meal, peanut meal, cottonseed meal and sunflower meal. The amount of feed provided was regulated according to the individual production, for each 2.5 milk liters the animals received 1kg of feed, so, the dairy control was done every day. The pasture was fertilized and had 4 acres, divided into 24 pickets, and each picket was occupied for one day. The experiment totalized 84 days, divided in 4 cycles of 21 days, where the first 14 were destined to the diets animals adaptation and the remainder to data collections. The milk samples were collected between the 18 th and 21 th day of each period, for further fat, crude protein, lactose, total solids and dry extract analysis. According to the SAS statistical program, using the Tukey’s test (P> 0.05) and analysis of variance there was no significant difference in the crude protein, lactose, total solids and dry fat analyzes, but in all of them the treatment with Peanut meal presented better or numerically bigger values. Only in the milk fat analysis, the animals that consumed peanut meal had statistically significant differences (P> 0.05), presenting higher values than the others. Among the analyzed variables, the treatment in which the animals consumed peanut meal presented the best values in relation to milk quality, with better fat, protein, lactose, dry extract and total solids percentages. Being a more desired agroindustry’s milk, for having a better yield.