Abstract 280

Paiva,JA-de-J; Cruz,-GM-da; Carvalho,-MR-de; Lobato-Neto,-J; Moreira,-HA; Neto,-J-Lobato

Empresa de Pesquisa Agropecuaria da Bahia SA, Caixa Postal 1.222, CEP 40000 Salvador, Brazil.

Pesquisa-Agropecuaria-Brasileira. 1986, 21: 1, 67-77; 34 ref.

24 Friesian X zebu cows in 2 groups were given in wk 1-12 of lactation diets of maize silage with concentrates to supply 120 or 80% of estimated requirements for crude protein and TDN according to NRC (1978) standards for production of 12 kg milk per day, and in the remainder of lactation diets of elephant grass with concentrates to supply 100% of estimated requirements. In wk 1-12 4%-FCM yield of cows in the 2 groups resp. averaged 15.7 and 13.9 kg/day (P < 0.05); in wk 13-24 and wk 25 onwards daily FCM yield did not differ significantly between groups, averaging 9.2-9.8 and 5 kg resp. Milk composition did not differ between groups in any period. Milk yield was higher than predicted from nutrient intakes in wk 1-12, particularly for the cows given 80% of requirements, which lost on average 0.44 kg body weight per day; yields were close to predictions in wk 13-24 and lower in wk 25 onwards. The period from calving to 1st oestrus was longer for cows fed above requirements than for cows fed below requirements (42.2 vs. 30.3 days), but calving interval was shorter (351.6 vs. 363.6 days).