Effect of concentrate feeding to sukling fcmalc calvos on growth and reproduction / Eficácia da administração de ração a bezerras lactentes e conseqüências na desmama, recria e reprodução

ABSTRACT

In this study 64 crossbred Santa Gertrudis female calves born from february to may of 1975 and 1976 were used to study the effect of supplementary feed up to weaning (seven months), on growth rate and on reproductive performance. A completely randomized design with two treatments (A = control, B = supplemented) and 16 replications was used each year. The calves of treatments A were kept with their mothers on pasture all the time, the ones of treatment B were separated from their mothers for a period of 8 hours during the day. During this period they were kept on a grass paddock and received their supplementary feed (80% ground whole ear com and 20% soybean meal). Before joining their calves, the cows of treatment B were milked. The average supplementary feed intake for treatment B was 289.3kg per calf. Average liveweights at 0, 120, 205. 365, 420 and 550 days of age were 31.2 and 33.1; 99.3 and 107.4; 139.5 and 180.0; 178 and 211; 206.0 and 225.0; 294 and 310kg, for treatments A and B, respectively. The breeding season was from October to January, when the heifers were about 22 months old. The calving percentages in the first calving were 71.1 and 85.7 for animals born in 1975 and 75.0 and 87.5% for animals born in, 1976, for treatments A and B, respectively. The average milk production of cows on treatment B was 284.2kg in 1975 and 258.6kg in 1976.

RESUMO

Foram utilizadas bezerras cruzadas santagertrudi, nascidas no período de fevereiro a maio de 1975 e 1976 em delineamento inteiramente casualizado com dois tratamentos e 16 rapaticões. Os tratamentos diferiam apenas na fase de criacão. A recria e as coberturas das novilhas processavam-se no pasto. No tratamento A, as bezerras e suas mães permaneciam em regime extensivo e, no B, apenas as vacas. As filhas destas últimas eram apartadas de manhã, ficando oito horas em piquetes, tendo á disposição uma mistura da 80% de quirera de milho e 20% de farelo de soja, e retornavam ao pasto à tarde, após a ordenha de suas mães. As bezerras do tratamento B consumiram, em média, até á desmama, 273kg de ração. O peso ao nascer foi influenciado pelo ano de nascimento (P 0.05), A suplementação durante a fase de aleitamento aumentou o peso à desmama (P 0.01), permanecendo essa superioridade durante a fase de recria. Os pesos médios às idades padrões de 0, 120, 205. 365, 20 e 550 dias, para os tratamentos A e B, foram respectivamente 31.2 e 33.1 kg 99.3 e 107,4kg; 139,5 e 180,0kg; 178 e 211kg; 206 e 225kg e 294 e 310kg. A estação de cobertura das novilhas foi de outubro a janeiro, com idade média de 22 meses. Os índices de natalidade na primeira parição foram 71,1 e 85,7% para as novilhas nascidos em 1975. e 75,0 e 87.5% para as nascidas em 1976, respectivamente para os tratamentos A e B