Detoxified castor seed meal replaces soybean meal in the supplement for Holstein-Zebu crossbred steers finished on tropical pasture during the rainy season.

The objective of this study was to examine the effect of replacing soybean meal (SBM) with detoxified castor seed meal (DCM) on the intake, digestibility, feeding behavior, and performance of pasture-finished (rainy season) steers supplemented with concentrate at 0.4% of their body weight. Forty ½ Holstein + ½ Zebu steers (initial weight: 283.3 ± 36.3 kg) were allocated to four treatments in a completely randomized experimental design. Treatments consisted of diets in which DCM replaced 0, 30, 60, and 90% of SBM in the supplement dry matter (DM). The steers were finished on an Urochloa brizantha pasture and the experiment lasted 112 days. Replacing SBM with DCM did not influence (P > 0.05) the intake or apparent digestibility of DM, crude protein, or neutral detergent insoluble fiber of the animals. Grazing time increased (P < 005), whereas the intake and rumination efficiencies of the steers did not change (P > 0.05) with the substitution. The replacement of SBM with DCM in the supplement fed to the steers also did not influence (P > 0.05) their final weight, average daily gain, or feed conversion (P > 0.05). We recommend replacing up to 90% (DM basis) of SBM with DCM in the concentrate supplement of steers grazing on Urochloa brizantha pasture during rainy season while supplemented with concentrate at 0.4% of their body weight.