Terminação de novilhos em pastagem de Brachiaria brizantha, com diferentes níveis de suplementação, durante o período das águas

• Autor(a) principal: Lambertucci, Daniel Moreira
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5719
• topic: Suplementação a pasto; Desempenho animal; Carcaça; Pasture supplementation; Animal performance; Carcass; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The objective of this trial was to evaluate the effects of different supplementation levels on performance, chemical composition and carcass characteristics of steers from different genetic groups of finishing steers grazing Brachiaria brizantha cv. Marandu pasture. Fifty-four steers averaging 20 months old were divided in three groups according to the initial body weight (criterion adopted by the farmers), as follows: 1) 23 steers averaging 325+25 kg and fed mineral salt (control), 2) 17 steers averaging 362+14 kg fed concentrate at 0.125% of body weight, and 3) 14 steers averaging 407+24 kg fed concentrate at 0.250% of body weight. The supplements contained corn, soybean meal, and starea formulated to yield 24% crude protein. Three ruminally fistulated steers averaging 20 months old and 420+25 kg were used for evaluation of dry matter intake and ruminal parameters. The animals of treatments 1, 2 and 3 intaked of 0.070, 0.490 and 1.100 kg/day; and averaged daily gain of 0.631, 1.099 and 1.161 kg/day, respectively. It was observed feed:gain ratio of 0.91:1 and 10:1 kg, respectively, at 0.125 and 0.250% BW levels. The increasing supplementation levels, during the finishing phase of grazing steers, provided higher values of weight gain at 0.250% BW levels, but with better feed:gain ratio at 0.125% BW level. No difference (P>0.05) on dry matter forage intake by increasing the levels of supplementation was observed. It was observed significant effect (P<0.05) of supplement x hour interaction on ammonia and pH values. The pH values for all treatments averaged 6.2, below which inhibit fiber digestion. The ruminal ammonia contents of the supplemented animals (0.125 and 0.250% BW) were always higher than the threshold value of 10 mg/dL that maximize microbial growth and ruminal digestibility in tropical conditions. Fourteen steers from different genetic groups (seven ½Nelore x ½Santa Gertrudis, four ½Nelore x ½Simental and three Nellore) averaging 481+30 kg of weight and 24 months old were slaughtered to evaluate chemical composition and carcass characteristics. No significant effects (P>0.05) among genetic group on slaughter weight, carcass weight, carcass yield, beef round weight, beef round yield, short ribs weight, beef plate weight, fat thickness, and loin eye area were observed. It was observed difference (P<0.05) for the percentages of humidity, ash, protein, total lipid and cholesterol among the genetic group. It was observed higher (P<0.05) linoleic acid content (CLA) on the Longissimus dorsi muscle of crossbred ½Nellore x ½Santa Gertrudis than ½Nellore x ½Simental and Nellore. The meat of grazing ½Nelore x ½Santa Gertrudis showed high nutritional quality than the other genetic groups.