Consumo e digestibilidade aparente da torta de mamona destoxificada em substituição ao farelo de soja na dieta de ovinos

Abstract

Castor cake is a byproduct of biodiesel industry with high nutritional value for use in ruminant feeding, however, its use is restricted due to the presence of ricin. Although methods of detoxification have been studied for many years, there are still few studies evaluating the effects of this by-product on animal nutrition and its nutritional potential in function of detoxification and chemical composition. In this way, it is opportune to study nutrient use capacity of detoxified castor cake in ruminant animal diet. The objective of this study was to evaluate the influence of partial substitution of soybean meal for detoxified castor cake on the consumption, apparent digestibility of nutrients, and synthesis of microbial nitrogen compounds, nitrogen balance, ruminal parameters, ruminal microbiota and enteric methane emission of sheep fed with this by-product. For this, 10 sheep, male, castrated, Santa Inês breed, with initial mean body weight (BW) of 42.87 ± 3.72 kg were distributed in a randomized complete design and divided into two groups: control and test, substitution of 50% of soybean meal for detoxified castor cake (DCC). The DCC showed ricin concentrations of 0.303 mg g-1 and ricin consumption was 0.59 mg kg-1 day-1 body weight. production ofshort chainfatty acids were not changed either, except for acetate, which increased with the inclusion of DCC in relation to the diet with soybean meal. Nevertheless, no change was observed in acetate: propionate ratio. The species relative abundance of F. succinogenes, R. flavefaciens, S. ruminantium and fungi, absolute population of Archaea metanogenics, and protozoa number were not changed by DCC inclusion in comparison to control diet, as well as methane emission. Despite the potential for replacement of soybean cake by the detoxified castor cake, the reduction in apparent digestibility of some nutrients may reflect in lower animal performance.