Fornecimento de suplementos com diferentes níveis de energia e proteína para vacas Jersey e seus efeitos sobre a instabilidade do leite

Abstract

The aim of the study was to evaluate the effects of supplements with three combinations of energy and protein on milk production, milk physical and chemical characteristics, body weight, body condition score and blood biochemical profile of the cows. It was used, in this experiment, 24 lactating cows on natural fields distributed in a complete random design, receiving one of the following supplements: low levels of energy and protein, low level of energy and high level of protein or high levels of energy and protein. Compared to the low energy and protein supplement, high energy and protein supplement reduced milk instability in the alcohol test, it increased milk production in 50%, and body condition score of the cows in 18%. In addition, it increased milk components and blood biochemical profile of the cows: 13% in lactose content; 9% in non-fat dry extracts; 21% in glucose plasmatic levels, 24% in phosphorus content, 16% in creatinine content, 9% in magnesium contents; and it reduced ureic nitrogen in 40%. The supplement with high levels of energy and protein was more efficient than the others in improving milk stability in the alcohol test, body condition score and contents of some chemical components of the milk and of blood. © 2010 Sociedade Brasileira de Zootecnia.