Arquivo Brasileiro de Medicina Veterinária e Zootecnia (Apr 2008)
Consumo, desempenho e parâmetros econômicos de novilhos Nelore e F1 Brangus x Nelore terminados em pastagens, suplementados com mistura mineral e sal nitrogenado com uréia ou amiréia Feed intake, performance and profitability of Nellore and crossbred (Brangus x Nellore) steers finished in pastures, supplemented with mineralized salt and nitrogenous salt with urea or starea
Abstract
Avaliou-se o efeito da suplementação protéica (40% PB) com amiréia ou uréia sobre o consumo de suplemento, desempenho e características econômicas de novilhos terminados em pastagens. Foram utilizados 120 novilhos com 19 meses de idade e 358kg, sendo 60 Nelore e 60 F1 Brangus x Nelore, divididos em três tratamentos com 20 animais, alojados em piquetes de Brachiaria brizantha cv. Marandu de 10 hectares cada, totalizando 120 hectares, sendo dois piquetes por grupo genético e tratamento, pastejados alternadamente a cada pesagem (42 dias). Os tratamentos consistiram em mistura mineral com amiréia-150S (AM), mistura mineral com uréia+milho+enxofre (UR) e mistura mineral (MM). As médias de consumo de suplemento dos animais F1 foram de 206,1; 145,9 e 73,1g/dia, e as dos animais Nelore, 236,0; 205,1 e 94,3g/dia para os tratamentos AM, UR e MM, respectivamente. Para os novilhos Nelore, houve efeito (PThe effects of protein supplementation of finishing grazing steers by feeding nitrogenous salts (40% CP, urea or starea) or mineralized salt only on supplement intake, growing performance and profitability were evaluated. One hundred and twenty steers (60 Nellore and 60 Brangus x Nellore, 19-month old, 358kg BW) were divided in 12 equal groups which were allotted to one of 12 Brachiaria brizantha pastures (10-ha each) performing two pastures for each breeding group and nutritional treatment. Groups were allowed to graze each pasture for 42 days when they were randomly moved into a new one. Nutritional treatments were as follow: MS - mineralized salt only; ST -mineralized salt plus starea - 150S; and UR - mineralized salt plus urea, corn and sulphur. UR supplement was prepared mixing the same ingredient contents of ST. Crossbred steers consumed 206.1; 145.9 and 73.1g/day whereas Nellore steers consumed 236.0; 205.11 and 94.29g/day of ST, UR and MS; respectively. For Nellore steers, UR increased slaughter weight (518.8kg) compared to ST and MS (491.9 and 485.2kg, respectively). Protein supplementation also increased slaughter weight for crossbred steers (P<0.05) in comparison to animals fed mineralized salt as sole supplementation (515.9 and 520.2kg for the UR and ST, respectively). Protein supplementation enhances growing performance of crossbred steers during periods of forage abundance. Urea supplementation yields a higher profitability in grazing systems for cattle finishing.
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