Relationship between gain rate during the growing phase and forage allowance in the finishing phase in Nellore cattle.

Abstract

The study evaluated the effect of gain rates during the growing phase and the possible interaction with finishing phase forage allowance in beef cattle. In Exp. 1, eighty Nellore cattle (386 ± 7.90kg; divided into 16 paddocks) were used in a randomized block design in a 2 × 2 factorial arrangement of treatments: (1) gain rate during the growing phase (low and high); (2) forage allowance during the finishing phase (low and high). In Exp. 2, twelve cannulated animals were used to evaluate ruminal parameters at the finishing phase. The animals were supplemented (2% of body weight [BW]) during 112days. The average forage mass was 6507 and 2712kg DM/ha, resulting in a forage allowance of 2.91 and 1.31kg DM/kg BW, respectively, for high and low supply. In Exp. 1, there was interaction among factors (P= 0.01) for average daily gain (ADG): low gain rate animals that were finished on high forage allowance had an ADG 0.203kg/day greater than average of other treatments (0.917kg/day). Animals with a high gain rate in the growing phase started the finishing phase 51.5kg heavier than low gain rate animals; this difference dropped to 35.5kg in final BW (P< 0.01). In terms of the carcass, this difference was 27kg at the beginning and dropped to 25kg at the final carcass weight (P< 0.01). In Exp. 2, the acetate concentration at the end was higher for animals fed high forage allowance compared to low. However, propionate concentration was higher for animals fed low forage allowance compared to high (P= 0.01). Our results showed that the growing phase influences performance during the finishing phase; however, forage allowance with high supplementation at the finishing phase had negligible effects under these experimental conditions.