Desempenho de bovinos superprecoces não castrados ou castrados em diferentes idades criados no sistema pasto/suplemento / Performance of young beef cattle uncastraded or castraded in grazing reared in pasture system/supplement

AUTOR(ES)

Anilza Andréia da Rocha

DATA DE PUBLICAÇÃO

2010

RESUMO

This work was developed in two chapters. The objective of the study described in the first chapter was to evaluate the performance nutritional and carcass traits of grazing young bulls castrate at different ages or not, supplemented or not. Fourty seven crossbred Nellore young bulls with initial age of 120 30,1 were used, housed in paddocks of Brachiaria decumbens Stapf. The animals were distributed randomly in a factorial arrangement with four ages of castration and two supplementation systems. The pastures were evaluated every 28 days. The prediction of intake and digestibility used the indicators: LIPE, titanium dioxide and neutral detergent fiber indigestible. Urine and blood samples were collected too. The concentrate supplementation improved the utilization of pasture, despite it caused a substitutive effect at all seasons evaluated. Castration of animals around the weaning time, at the beggining of the dry season hindered the animal development for, at least, six months after that castration. The trial described in the second chapter had the objective to evaluate the carcass characteristics and estimate the energy, protein and macrominerals requirements of supplemented crossbreds bulls in grazing Brachiaria decumbens Stapf. pasture, castrade at different ages or not castrade, and supplemented or not. Fourty seven young bulls with average initial age of 120 30,1 days. Four animals were slaughtered as reference at the beginning of the experiment. To estimate the net energy requirements for weight gain were adjusted a equation regressing the retained energy by the empty body weight gain and the metabolic empty body weight. To estimate the net protein requirements for weight gain, were adjusted a equation regressing the retained protein by the empty body weight gain and the energy contend of this gain. The net requirements of Ca, P, Mg and Na for weight gain were determined by the equation Y’ = b. a . Xb-1, where a and b represent the intercept and the regression coefficient, respectively. The castration or the supplementation did not affected the body weigt gain requirements.

ASSUNTO(S)

ruminantes consumo rendimento carcaça nutricao e alimentacao animal ruminants intake income carcass

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