Finishing of grazing crossbred steers supplemented with detoxified castor bean meal (Ricinus communis L.) in the rainy-dry transition period

Abstract

This study examined different levels of replacement of soybean meal with detoxi ed castor bean meal in the nishing of crossbred steers on Brachiaria brizantha cv. Marandu pasture during the rainy-dry transition period. Forty Holstein-Zebu crossbred steers with an average initial weight of 395.93 ± 10 kg were randomly allocated to four treatment groups that were supplemented with concentrate containing different levels of castor bean meal replacing soybean meal (0, 30, 60, or 90%; at 0.4% body weight [BW]).The experimental period was 112 days. A completely randomized experimental design was adopted; with regression analysis conducted using the Statistical and Genetic Analysis System (SAEG). Intake and digestibility of dry matter (DM) and nutrients and animal performance were evaluated. The replacement of soybean meal with castor bean meal did not in uence (P>0.05) the intakes of DM (kg day -1 ), organic matter (OM, kg day -1 ), neutral detergent ber (NDF, kg day -1 and %BW), non-brous carbohydrates (NFC, kg day -1 ), or total digestible nutrients (kg day -1 ). However, the intakes of crude protein (CP) and ether extract (EE, kg day -1 ) decreased as the replacement levels were increased (P<0.05). The digestibility of DM, OM, NDF, and EE did not change, whereas CP digestibility decreased linearly and NFC digestibility increased linearly (P<0.05). The replacement levels did not affect (P>0.05) nal live weight, average daily gain, feed conversion, or carcass yield. Detoxi ed castor bean meal can replace up to 90% of soybean meal in the composition of the supplement without compromising the production performance of steers on Brachiaria brizantha cv. Marandu pasture during the rainy-dry transition period.