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Acta sci. vet. (Impr.); 41: Pub. 1125, 2013. tab, graf

Artigo em Português | VETINDEX | ID: biblio-1372452

Resumo

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 on parameters 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 placebo injections. The heifers receive three injections of rbST and placebo 14 days apart in the prepartum period. The diets of group bST and CON was according to 100% of requirements and DMI was calculates using the body weight, BCS, age, period of gestation and growth. The serum glucose, NEFA, calcium and phosphorus concentration were analyzed in blood samples through colorimetry method. Gamma glutamyltransferase and aspartate aminotransferase activity were measured by spectrophotometer. All statistical analyses were made using softweare SAS. Glucose, NEFA, urea, calcium, phosphorus and relashioship C:P, GGT and AST were analyzed through MIXED procedure and the Tukey-Kramer test was applied for comparision means. For the BCS analyzis was applied Kruskal-Wallis test.The BST group had higher plasmatic concentrations of glucose than CON group (P = 0.0011). Similarly urea concentration was lower for BST group (P = 0.0099) during prepartum. The NEFA concentration was higher in REST than CON group (P = 0.0015). We did not find difference between groups for BCS, mineral profile and enzymatic profile. Discussion: The feed restriction increased NEFA concentration due to decreased DMI. On the BST group, we observed higher concentrations of glucose when compared with CON group, resembling to the results found by others. In accordance to our results previous studies, no difference concerning urea concentration in prepartum period in cows submitted to feed restriction or mineral profile for cows submitted to feed restriction and bST treatment was found. This strategy will also result in increased lipolysis, causes protein degradation stemmed from muscle tissue in an attempt to maintain the levels of glucose from gluconeogenesis from amino acids. Disagreeing the results described here, others observed higher BCS in cows submitted to ad libitum diet compared with feed restriction cows during prepartum. In this study feed restriction and bST on prepartum period can improve metabolic adaptation, but these two strategies do not act in synergy.

Biblioteca responsável: BR68.1