Effect of prepartum feed restriction and bovine recombinant somatotropin injection on plasmatic parameters of prepartum Holstein heifers / Efeitos da restrição alimentar e administração de somatotropina recombinante bovina nos parâmetros plasmáticos de novilhas da raça Holandês durante o período pré-parto

ABSTRACT

Background: During the transition period negative energy balance (NEB) occurs due to the difference between input and output of nutrients. At this period, these nutrients are directed to milk production and lipolysis is the major mechanism of adaptation. There is an increase of the non-esterified fatty acids (NEFA) reduce dry matter intake (DMI). The feed restriction during the prepartum period improve milk production and plasmatic concentration of glucose and insulin through the adaptation of liver enzymes and increased DMI at the postpartum period. The administration of recombinant bovine somatotropin (rbST) also improve milk production on postpartum period and alters lipogenesis and lipolysis through effects on adipose tissue and lipid metabolism. The aim of this study was to evaluate the effects of feed restriction and injections of rbST onparameters of energetic, protein, enzymatic and mineral metabolism of prepartum dairy heifers. Materials, Methods & Results: Fourty four heifers with BW = 477.2 ± 7.4 kg at the beginning were used. The experimental period ranged from 35 days prepartum to calving. These heifers were divided in four groups with 11 heifers each bST fed to allow 100% of the DMI plus rbST injections; RbST fed to allow 80% of the DMI plus rbST injections; CON fed to allow 100% of the DMI plus placebo injections and RES fed to allow 80% of the DMI plus

RESUMO

O periparto impõe grandes mudanças fisiológicas em vacas leiteiras, determinando um aumento na ocorrência de distúrbios metabólicos. Neste período, os nutrientes são direcionados para a produção de leite e como mecanismo de adaptação há um aumento na mobilização de tecido adiposo devido ao balanço energético negativo (BEN). Estudos mostram que a restrição de 20% da ingestão de matéria seca (IMS) e o uso de somatotropina bovina recombinante (rbST) no período pré-parto podem minimizar os efeitos indesejados do BEN pelo aumento da IMS pós-parto. [...]