Replacement of soybean meal by treated castor meal in supplements for grazing heifer during the dry-rainy season period

Abstract

The objective of this work was to evaluate the effect of multiple supplement with different levels of castor meal (Ricinus communis L.) treated with calcium oxide on intake, on the total apparent digestibility of dietary components, on the efficiency of microbial synthesis and on the performance of beef heifers grazing Brachiaria decumbens during the dry-rainy transition period. The experimental area was composed of five 2.5-ha paddocks with availability of potentially digestible dry matter of 2,858.4 kg/ha. It was used 25 Nellore heifers and 10 crossbred with predominance of Zebu breed heifers at 13 months of age and body weight of 210 ± 0.8 kg in a completely randomized experimental design. Supplements contained approximately 25% of crude protein (CP) and they were formulated with 0; 33; 67 and 100% of castor meal replacing soybean meal. Daily weight gain was 366.1 g for animals in the control group and 439.7; 478.9; 556.3; and 493.9, respectively for those fed supplements with 100% of soybean meal and 33, 67 and 100% castor meal. There was no effect of treated castor meal levels on daily weight gain of the animals, which was higher in those animals fed supplements. Levels of castor meal had decreasing linear effect on intakes of dry matter (DM), organic matter (OM), ether extract (EE), digested dry matter and digestible neutral detergent fiver and on the intake of total digestible nutrients. Coefficients of apparent digestibility of DM, OM, CP, EE and non-fibrous carbohydrates were greater for animals under supplementation. Microbial efficiency, expressed in g of crude protein per kg of consumed TDN, did not differ among groups. Replacement of soybean meal by castor meal treated with calcium oxide does not harm animal performance.