Desempenho bioeconômico de ovinos alimentados com rações contendo farelo de mamona destoxificado.

Resumo: Objetivou-se avaliar o efeito da substituicao do farelo de soja pelo farelo de mamona destoxificado sobre o consumo e o desempenho de ovinos. Foram utilizados 20 borregos, mesticos, machos, inteiros, com peso vivo medio de 19,3 ± 1,35 kg e idade media de 7 meses, e distribuidos aleatoriamente em quatro tratamentos de 0, 50, 75 ou 100% de substituicao, com base na materia seca. O volumoso utilizado foi o feno de capimelefante. As racoes foram fornecidas diariamente em duas refeicoes, coletandose no dia seguinte as sobras, que foram pesadas, mantendoas em torno de 15%. O periodo experimental teve duracao de 70 dias, apos os quais os animais foram abatidos. Os ensaios experimentais foram realizados num delineamento inteiramente casualizado com quatro tratamentos e cinco repeticoes (ovinos). Na avaliacao do comportamento ingestivo, as variaveis: tempo de alimentacao, ruminacao, outras atividades, ocio, consumo de sal e ingestao de agua foram afetadas pelos tratamentos e periodos do dia. A frequencia de miccao e de defecacao foi afetada apenas pelos periodos do dia. No numero de mastigacoes mericicas por bolo ruminal observouse inferioridade para 100% de substituicao. Na avaliacao do consumo e desempenho animal, nao houve diferenca para o ganho medio diario e numero de dias para ganhar 12 kg. A analise de regressao revelou efeito quadratico para a conversao alimentar, apresentando um nivel biologico otimo de 59% de substituicao do farelo de soja pelo farelo de mamona destoxificado. Nao houve diferencas significativas para os consumos de materia seca, fibra em detergente neutro, fibra em detergente acido, hemicelulose e materia mineral (em g/animal x dia, % PV, e g/UTM). Observouse menor consumo de extrato etereo para o nivel 75% de substituicao e de proteina bruta nos niveis 50 e 75% de substituicao. Na avaliacao da carcaca e dos seus nao componentes, nao foram observadas diferencas entre os niveis de substituicao para as variaveis: peso vivo, peso vivo de abate, perdas devido ao jejum, peso da carcaca quente, peso da carcaca fria, perdas por resfriamento, comprimento da carcaca, perimetro da garupa, largura da garupa e grau de acabamento. A analise de regressao revelou efeito quadratico para rendimento verdadeiro e biologico, apresentando um nivel biologico otimo de 100% de substituicao. Ja na avaliacao dos nao componentes da carcaca, nao foram observadas diferencas para as visceras, trato gastrintestinal cheio, gastrintestinal vazio, orgaos genitais, cabeca e patas. Para a variavel pele, a analise de regressao revelou efeito quadratico, apresentando um nivel biologico otimo de 44% de substituicao. Quando se efetuou a analise bioeconomica da alimentacao oferecida no experimento, verificouse que nao houve diferenca para o ganho de peso total e eficiencia alimentar. A analise de regressao revelou efeito quadratico para a eficiencia alimentar, apresentando um nivel biologico otimo de 56% de substituicao do farelo de soja pelo farelo de mamona destoxificado. Nenhum dos tratamentos apresentou lucratividade; por outro lado, a margem bruta (R$/kg PV), margem liquida (R$/kg PV) e o lucro (R$/kg PV) obtido no nivel 0% de substituicao apresentaram resultado positivo para tais indices, com valores de R$ 0,69/kg PV, R$ 0,66/kg PV e R$ 0,59/kg PV, respectivamente; quando o preco de venda do peso vivo foi de R$ 5,20. A substituicao de 100% do farelo de soja pelo farelo de mamona destoxificado nao altera substancialmente o comportamento ingestivo de borregos terminados em confinamento. O desempenho destes animais foi satisfatorio, tendo proporcionado melhor conversao alimentar no nivel de 59% de substituicao. As caracteristicas da carcaca e dos seus nao componentes nao foram afetadas pela utilizacao em ate 100% de substituicao, tendo a variavel pele apresentado um nivel biologico otimo de 44% de substituicao do farelo de soja pelo farelo de mamona destoxificado. Porem, a utilizacao do farelo de mamona destoxificado por autoclavagem em racoes para a terminacao de borregos nao se apresenta como alternativa viavel para garantir lucro ao produtor, pois esta atividade so seria viavel se o preco de venda do borrego fosse superior a R$ 9,25/kg PV. To evaluate the effect of substitution of soybean meal by detoxified castor meal on consumption and performance of sheep this research was carried out. Twenty crossbred lambs, male, whole, weighting 19.3 ± 1.35 kg, averaging 7 months of age were randomly assigned to four treatments of 0, 50, 75 and 100% of substitution, on dry matter basis, were used the roughage used was elephant grass (Pennisetum purpureum Schum.) hay. The diets were balanced to be isonitrogenous and isocaloric, delivered in two daily meals, collecting the following day the leftovers, which were weighed, keeping them around 15%. The experiment lasted for 70 days, when animals were slaughtered. The experimental trials were conducted in a completely randomized design with four treatments and five repetitions. In the assessment of ingestive behavior, the parameters of feeding time, ruminating, other activities, leisure, consumption of salt and water intake were affected by treatments and periods of the day. The urination and defecation were affected only by time of day, in jaw movements per ruminal bolus there was inferior to 100% substitution. In the assessment of consumption and performance, there was a significant difference to the feed conversion, determining that the 50% level of substitution improved better performance of animals. However, there was no significant difference for average daily gain and number of days to reach 12 kg. The regression analysis showed a quadratic effect for the feed conversion, with a biological optimum level to 59% substitution of soybean meal by detoxified castor meal. There were no significant differences for the intake of dry matter, neutral detergent insoluble fiber, acid detergent insoluble fiber, hemicellulose and mineral matter (in g/animal x day, % BW, and g/UMS). There was less consumption of ether extract for the 75% level of substitution and crude protein levels in 50 and 75% for replacement. Related to carcass evaluation and non carcass components, no significantly differences were observed among the levels of substitution for the variables body weight, weight of slaughter, losses due to fasting, hot carcass weight, cold carcass weight, cooling losses, length of carcass, hip of perimeter, hip width and degree of resignation. The regression analysis showed a quadratic effect for real and biological yields, with a great organic level of 100% substitution. In non carcass components, no significantly differences were registered for viscera, full gastrointestinal tract, empty gastrointestinal tract, genitals, head and legs. For the variable skin, the regression analysis showed a quadratic effect, presenting a point of maximum at 44% for replacement. Castor bean meal can substitute 100% of soybean meal. The result of the economic analysis of food offered in the experiment, showed that none of the treatments were profitably. Moreover, considering the gross (US$/kg BW), net (US$/kg BW) and profit (US$/kg BW) margins obtained, it appeared that only the level of 0% substitution showed positive values for such indices (US$ 0.31/kg BW, US$ 0.29/kg BW and US$ 0.26/kg BW, respectively), when the selling price of live weight was of US$ 2.26. The replacement of up to 100% of soybean meal by detoxified castor meal do not alter significantly the ingestive behavior of lambs finished in feedlot. Detoxified castor bean meal shows potential for use as feed for sheep in termination, promoting lower consumption of crude protein with no change in average daily gain at 100% and good feed conversion, at 59% for replacement. The characteristics of the carcass and non carcass components were not affected by use in up to 100% of substitution, and the variable skin presented a biological level optimum when the soybean meal was replaced in 44% by detoxified castor meal. The use of autoclavedetoxified castor meal in rations for termination of lambs is not presented as a good alternative to guarantee profits to the producer, as this activity would only be viable when the sale price of the lamb is higher than US$ 4.03/kg BW.