Relações entre idade, peso, ganho médio diário e tempo médio de permanência de novilhos de corte confinados para abate aos 15 ou 27 meses de idade Relationships between age, weight, average weight gain and days on feed of beef steers slaughtered at 15 or 27 months of age

The main objective of this research was to evaluate the relationship between age, weight, average weight gain and days on feed of beef steers slaughtered at 15 or 27 months of age. Four hundred and thirty two beef steers were divided in two groups: 267 younger steers (YY), confined at 12 and slaughtered at 15 months old; and 165 young steers (YS), confined at 25 and slaughtered at 27 months of age. Beginning weight (BW) was 296.98 and 352.04 kg to YY and YS, respectively (p<0.01). Steers were on feedlot until reach a minimum fat percentage, resulting on seven different values for DF. In the statistical analysis the BW and the DF were calculated as co-variables. YS reach higher AWG (1.351 vs 1.004 kg/day) and higher SW (441.88 vs 388.88 kg) (p<0.01) and lower (p<0.01) DF (66.87 and 94.20 days, respectively). Steers with higher BW were sold earlier, reaching lower DF. Both groups showed a decrease tendency 1 2 Medico Veterinario. Mestrando do Programa de Pos-Graduacao em Zootecnia da UFRGS. Bolsista do CNPq. 3