Nutritive value of defective soybean grains for ruminants

Abstract

Defective soybean grains (DSBG) are considered improper for use as protein source in animal nutrition, what has not been evaluated yet. Thus, this study aimed to evaluate the in vitro fermentation and effects of DSBG in feedlot lamb diets. For that, two types of defective soybean grains (partially fermented and totally fermented) were obtained and compared to standard soybean grains (SSBG). In vitro, SBG (DSBG and SSBG) were evaluated alone or as component of a total mix ration which was also evaluated in vivo, where DSBG replaced SSBG in feedlot lamb diets. Before the studies, both types of SBG were sent to specialized laboratory where the presence of mycotoxins were no detected. Totally fermented SBG presented lower DM and carbohydrates content, but higher crude protein, fibre, and indigestible NDF contend than standard SBG. DSBG presented lower in vitro dry matter digestibility (IVDMD) than SSBG when evaluated alone, however when evaluated in experimental diets did not affect IVDMD. DSBG presented 57% lower in situ rumen degradable protein than standard SSBG (47.9 vs86.4%). In feedlot lamb diets DSBG did not affect nutrients intakes, apparent digestibility or animal performance. Thus, mycotoxins-free DSBG may totally replace SSBG in feedlot lamb diets.