Produção e composição química do leite de vacas da raça Jersey em função da categoria animal e do período de lactação

Abstract

Milk production and quality are influenced by factors such as breed, animal category and lactation period. between others. This study aimed to evaluate the chemical composition and milk production of Jersey cows as a function of animal category and lactation period. The work was carried out in the city of Veranópolis/RS, where 12 females were selected and distributed into three groups of 4 cows: primipara group; the secundiparous group and the multiparous group, during the first 23 weeks of lactation. The experimental design was completely randomized with four replications of each group, following a 3x5 factorial scheme (category x lactation month) for the qualitative analysis and 3x23 for the evaluation of productivity. The variables evaluated were milk production, chemical composition, somatic cell count and variation in body weight. Data were subjected to analysis of variance (ANOVA) and means were compared by Tukey tests (5%), using the Agroestat® program. Milk production was significantly influenced (p<0.05) by treatment and weeks of lactation, with averages, in liters, of 18.7b for primiparas, 21.7a for secundiparous and 21.5a for multiparous. The chemical composition of the milk was significantly influenced (p<0.05) by the category of animals and the week of lactation. The somatic cell count averaged 38.1 thousand cells/mL of milk. The Jersey breed animals evaluated produced milk with a composition greater than that required by legislation (IN's 76/77 of the MAPA), and the primiparous category presented lower milk production when compared to secundipeda and multiparous. [resumo fornecido pelo autor]