RESUMO

Two studies evaluated the productive characteristics of young Nellore heifers receiving different days on feed (DOF) to determine the biological slaughter endpoint. In Experiment 1 (Exp. 1), fifty-one Nellore heifers [324 ± 19.3 kg of body weight (BW); 16 ± 1 months] were split into three DOF lengths (45, 75, or 105 days), while in Experiment 2 (Exp. 2), thirty-six Nellore heifers (362 ± 25.5 kg of BW; 18 ± 1 months of age) were split into three DOF lengths (45, 90, or 135 days). In both studies, all animals were distributed in complete randomized blocks according to initial BW and stratified via carcass ultrasound. The diet was supplied ad libitum, allowing 3% of refusals. The point at which the animals achieved 25% of ether extract of shrunk body weight (EESBW) was defined as the biological endpoint. Thus, relationships were made between some characteristics obtained in both studies. Positive linear relationships were found between backfat thickness (BFT) vs. EESBW (p < 0.001, r = 0.84) and BFT vs. body weight (p < 0.001, r = 0.77). Our results suggest that the biological slaughter endpoint for young Nellore heifers is 6.97 mm of backfat thickness or 402 kg shrunk body weight, corresponding to around 75 DOF.

RESUMO

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 of AWG as the DF increased. YS reached higher AWG, resulting in lower DF compared with YY. In both groups, while the DF increases, the AWG decreases. Steers with higher BW reached lower DF.

Objetivou-se estudar as relações entre idade, peso, ganho médio diário de peso e tempo médio de permanência de novilhos de corte confinados para abate aos 15 ou 27 meses de idade. Foram utilizados 432 novilhos com base racial britânica e cruzas, sendo 267 novilhos superprecoces, confinados aos 12 meses e abatidos em média aos 15 meses (grupo NSP) e 165 novilhos precoces, confinados aos 25 meses e abatidos em média aos 27 meses (grupo NP). Os NSP e os NP iniciaram o experimento com peso médio (PMI) de 296,98 e 352,04 kg, respectivamente (p 0,01) e foram terminados em confinamento até que atingissem um grau de terminação adequado. Em virtude disso, ocorreram sete períodos diferentes de abate. Na análise estatística o peso médio inicial (PMI) e o tempo médio de permanência (TMP) foram utilizados como co-variáveis. O grupo NP apresentou maior (p 0,01) GMD (1,351 x 1,004 kg/dia) e PMF (441,88 x 388,88 kg) e menor (p 0,01) TMP (68,87 x 94,20 dias, respectivamente). O ganho de peso vivo (GPV) foi semelhante (p > 0,05) entre os grupos (91,90 e 89,27 kg para NSP e NP, respectivamente). Animais que apresentaram maiores PMI foram vendidos mais cedo, obtendo menores TMP. Nos dois grupos foi observada uma tendência de queda no GMD com o aumento do TMP. Novilhos precoces obtiveram maior GMD, acarretando em um menor TMP em relação aos superprecoces. Com o aumento do TMP houv

RESUMO

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 of AWG as the DF increased. YS reached higher AWG, resulting in lower DF compared with YY. In both groups, while the DF increases, the AWG decreases. Steers with higher BW reached lower DF.    

Objetivou-se estudar as relações entre idade, peso, ganho médio diário de peso e tempo médio de permanência de novilhos de corte confinados para abate aos 15 ou 27 meses de idade. Foram utilizados 432 novilhos com base racial britânica e cruzas, sendo 267 novilhos superprecoces, confinados aos 12 meses e abatidos em média aos 15 meses (grupo NSP) e 165 novilhos precoces, confinados aos 25 meses e abatidos em média aos 27 meses (grupo NP). Os NSP e os NP iniciaram o experimento com peso médio (PMI) de 296,98 e 352,04 kg, respectivamente (p 0,01) e foram terminados em confinamento até que atingissem um grau de terminação adequado. Em virtude disso, ocorreram sete períodos diferentes de abate. Na análise estatística o peso médio inicial (PMI) e o tempo médio de permanência (TMP) foram utilizados como co-variáveis. O grupo NP apresentou maior (p 0,01) GMD (1,351 x 1,004 kg/dia) e PMF (441,88 x 388,88 kg) e menor (p 0,01) TMP (68,87 x 94,20 dias, respectivamente). O ganho de peso vivo (GPV) foi semelhante (p > 0,05) entre os grupos (91,90 e 89,27 kg para NSP e NP, respectivamente). Animais que apresentaram maiores PMI foram vendidos mais cedo, obtendo menores TMP. Nos dois grupos foi observada uma tendência de queda no GMD com o aumento do TMP. Novilhos precoces obtiveram maior GMD, acarretando em um menor TMP em relação aos superprecoces. Com o aumento do TMP houv