Novilhas de corte suplementadas a pasto sob efeito da imunocastração

The objective of this work was to evaluate the effect of immunocastration and the use of mineral supplementation with grain, on Massai grass pastures (Megathyrsus maximus) during the rainy season, on the performance, blood biochemical profile and carcass and meat characteristic of ½ Nelore X Limousin heifers. Twenty-eight animals were used, with mean age and initial weight of 13 months and 217 kg, respectively. A completely randomized design with four treatments distributed in a 2 x 2 factorial arrangement was used, two sexual conditions (immunocastrated and non-castrated) and two types of supplementation (mineral supplementation with grain and common mineral). The mineral supplement with grain and the common mineral supplement were supplied in quantity 75 g and 25 g/100 kg body weight, respectively. The immunocastration method consisted of two doses (initial and booster) of the anti-GnRH vaccine Bopriva®, 1 ml in each animal belonging to this treatment, administered subcutaneously. At the end of the experiment the animals were taken to the commercial slaughterhouse located in the city of Araguaína-TO. The slaughter took place following the standards of the industry. Heifers were approximately 18 months old and had no definitive tweezers (zero tooth). There was interaction (P<0.10) of the factors studied for the variables of final body weight and total weight gain, in which the immunocast heifers supplemented mineral supplement with grain promoted lower FBW and TWG (324.27 and 106.57, respectively), compared to uncastrated heifers, and equally supplemented (342.86 and 126.86 kg, respectively). The mean daily gain was influenced by the sexual status (P<0.10), in which immunocastration in heifers resulted in lower performance when compared to uncastrated heifers (0.788 vs 0.860 kg/day). Sexual condition and type of supplement did not influence serum levels of glucose, triglyceride, albumin, total protein and creatine. However, there was interaction (P<0.10) between the factors studied for alkaline ...