Produtividade e eficiência de vacas Nelore em pastagem de Brachiaria decumbens Stapf nos Cerrados do Brasil Central

Abstract

RESUMO -A produtividade de vacas Nelore foi estimada durante quatro anos em pastagem de Brachiaria decumbens Stapf, com correção inicial da acidez e da fertilidade do solo e livre acesso a uma mistura mineral. Foram determinadas as taxas de prenhez (TP), de natalidade (TN) e de desmama (TD), o peso à desmama dos bezerros (PD), a produção de quilos de bezerros por vaca (P) e a eficiência de produção de bezerro por vaca (E) e por área (EA), bem como o peso e a condição corporal (CC) das vacas antes da estação de parição (PAP e CCP), durante o acasalamento (PMA e CCM) e à desmama (PVD e CCD). A TP média foi de 87,5%, enquanto a TN e a TD foram de 81,7 e 77,2%, respectivamente, considerando-se todas as vacas expostas a touros. O PD médio foi de 170 ± 21,89 kg, com a média de 202 ± 16,48 dias de idade à desmama. A ordem de parto (OP) influenciou o peso dos bezerros à desmama. Bezerros mais pesados foram produzidos pelas vacas entre a OP3 e a OP9. A P e E por vaca exposta a touro foram de 130 e 32,19 kg, respectivamente, e a EA foi de 192 kg/ha. Nos períodos PAP, PMA e PVD, os pesos vivos foram de 471 ± 19,67 kg, 405 ± 21,48 kg, 410 ± 9,35 kg e as condições corporais 4,45 ± 0,30, 3,32 ± 0,44, 3,54 ± 0,19, respectivamente. A correlação entre peso vivo e condição corporal foi de 0,66. Vacas Nelore, em pastagem de Brachiaria decumbens Stapf com correção inicial da acidez e fertilidade do solo, apresentaram altos índices reprodutivos e produtivos. Vacas em ordens de parto intermediárias foram mais produtivas que as vacas no início e no final da vida reprodutiva.Palavras-chave: condição corporal, ordem de parto, peso à desmama, produção de bezerros por área, produção de bezerros por vaca, taxa de desmama Nelore Cows Productivity on Brachiaria decumbens Stapf Pasture on the Cerrado Region of Central BrazilABSTRACT -The productivity of Nelore cows on Brachiaria decumbens Stapf pasture was measured during four years, in a soil initially improved with limestone and fertilizer and with free access to a mineral mixture. Pregnancy rate (PR), calving rate (CR), weaning rate (WR), calves weaning body weight (BWC), productivity (P = kg of calf/cow) and efficiency (E= P/100 kg of cow) per cow, productivity per area (AP = calves kg/ha), as well as cow body weight and body condition before the calving season (CLW and CBC), at the middle of the mating season (MLW and MBC) and at weaning (WLW and WBC) were evaluated. Mean PR, CR and WR of 87.5, 81.7 and 77.2%, respectively, were observed. Mean LWC of 170 ± 21.89 kg and mean weaning age of 202 ± 16.48 days were observed. Significant effect of calving order (CO) on LWC was detected. Cows between CO3 and CO9 weaned the heaviest calves. Values of 130 kg and 32.19 kg were observed for P and E, respectively, with AP of 192 kg/ha. The CLW and CBC, MLW and MBC, and WLW and WBC were of 471 + 19.67 kg and 4.45 + 0.30; 405 + 21.48 kg and 3.32 + 0.44; 410 + 9.35 and 3.54 + 0.19, respectively. The correlation between body weight and body condition was of 0.66. Nelore cows maintained on a tropical pa...

Productivity and efficiency of cow herds submitted to two weaning ages

“…Barcellos et al (1996) obtained an average productivity of 117.9 kg (kg calf/cow), and 29.4 kg (kg calf/100 kg cow) efficiency when working with primiparous cows of the following genotypes: ½ Nelore ½ Hereford, ¼ Nelore ¾ Hereford, and purebred Hereford. These results are similar to those obtained by Vieira et al (2005) in Nelore herds in central Brazil. It must be noted that primiparous cows have lower body weight than multiparous cows, which may affect efficiency results, although primiparous cows tend to produce lighter calves at weaning.…”

“…Considering only those cows maintained in the herd after open cows were removed from the analysis, birth and weaning rates were 96.5 and 95.7%, and 95.7 and 90.0% for cows submitted to early and conventional weaning, respectively. Vieira et al (2005) evaluating cows of different ages in a Nelore herd in the central region of Brazil for four consecutive years, observed average birth and weaning rates of 81.7 and 77.2%, when all cows exposed to bulls were considered, and higher rates, of 93.0 and 87.0%, when open cows were not taken into account.…”

“…When conventional weaning were individually analyzed, birth and weaning rates increased, probably because cows aged and were no longer primiparous cows (Vieira et al, 2005) thereby, had lower nutritional requirements (Freetly, 1999;Restle et al, 2001). Moreover, post-calving cows were offered better feeding conditions at the end of the second breeding season, when they were managed on Brachiaria brizanta, with 2,450 kg/ha available dry matter, contrary to the first year, when they grazed on natural pastures with only 1,640 kg/ha availability due to the high stocking rate of 320 kg/ha/year.…”

“…In studies on herd productive efficiency, herds are submitted to the same management conditions (Barcellos et al, 1996;Ribeiro et al, 2001;Vieira et al, 2005). Most authors state that the ratio between calf weight and cow weight within a same production cycle is adequate to measure efficiency at individual or herd level (Barcellos et al, 1996;Ribeiro et al, 2001).…”

“…The productivity of breeding systems may be increased by using of technological processes (Costa et al, 1981;Vieira et al, 2005), aiming at improving dam nutritional status and body condition throughout the year.…”