Efeito do grupo racial e do número de lactações sobre a produtividade e a composição do leite bovino

Abstract

Milk in Brazil is produced mainly by Holstein, Girolando and crossbred cattle. Animal breed and number of lactations are factor that can affect productivity and features of the milk. The purpose of this research was to evaluate the influence of breed and number of lactation on milk productivity, physicochemical composition, and Somatic Cell Count (SCC) from Holstein, Girolando and crossbred cattle. These data were collected from a farm, on the north of Parana state, from 2006 to 2011. The relations among the parameters were evaluated by correlation test and the effects of breed and number of lactations (1-6) by variance analysis and Tukey’s test. Holstein showed the highest productivity (p<0.05). Milk from crossbred and Girolando presented similar protein, lipid and total solids contents, which were superior to the values from Holstein milk. The breed groups did not differ in SCC and lactose content. Milk production and SCC increased until 3rd and 5th lactations, respectively, while lactose contents were reduced continuously after the 1st lactation and protein and lipid contents were little affected. All parameters correlations were significant (p<0.05), being the highest: milk production x protein and lactose contents, total solids content x lipid and protein contents, lipids content x protein content, and SCC x lactose content. Holstein was found the most productive; however, its milk had smaller concentration of proteins and lipids than milk from Girolando and crossbreed animals, which presented milk features and production similar between themselves.