Effects of supplements containing different additives on nutritional and productive performance of beef cattle grazing tropical grass.

Abstract

A grazing trial was carried out to evaluate the inclusion of three feed additives in supplements (crude protein, CP 230g/kg dry matter, DM) on the performance, voluntary intake, and digestibility of beef heifers grazing Brachiaria decumbens (CP 81 and neutral detergent fiber, NDF 615g/kg DM). Thirty-five Nellore heifers (21months of age and 383±6.29kg of body weight, BW) were used in a completely randomized design. The treatments were as follows: no supplement (control); supplement fed at 1kg/animal/day without additives (S); supplement with monensin (S+M); supplement with yeast culture (S+YC); and supplement with enzyme complex (S+EC). All of the supplemented heifers had greater (P<0.1) average daily gain (∼0.186kg/day) compared to the control treatment (0.014kg/day). Average daily gain and final BW were similar (P>0.1) among supplemented heifers. Monensin inclusion in the supplement decreased (P<0.1) forage DM (expressed as g/kg BW) and NDF intake (expressed as kg/day and as g/kg BW). All of the feed additive inclusions decreased (P<0.1) NDF digestibility. In conclusion, the heifers' performance was improved by concentrate supplementation. However, the inclusion of additives did not enhance this effect.