Food intake, milk production and body-weight change of milking cows given complete diets to appetite

Abstract

In each of 2 years, 20 Friesian cows were given either a low-energy or a high-energy complete diet to appetite during weeks 3 to 20 of lactation. The diets for trial 1 contained concentrates, lucerne silage and chopped grass hay in the proportions 33:47:20 or 58:29:13. In trial 2, concentrates and lucerne silage were mixed in the proportions 38:62 or 75:25. These mixtures had energy concentrations of 10·2 or 11·2 and 10·3 or 11·9 MJ metabolizable energy per kg dry matter (DM) and crude protein concentrations of 144 or 160 and 140 or 157 g/kg DM in the low- and high-energy diets of trials 1 and 2 respectively.Cows offered the low-energy diet consumed less DM daily (14·5 v. 17·4 (P < 0·001) and 15·2 v. 18·2 (P < 0·001) kg DM per day in trials 1 and 2). Daily milk yields were lower with low-energy diets (19·2 v. 22·3 (P < 0·001) and 18·7 v. 24·2 (P < 0·001) kg/day in trials 1 and 2), and there were significant differences between treatments in milk composition and live-weight changes.The correlation between food intake and milk yield during weeks 3 to 20 was moderately strong (r2 = 0·58). Variation in food utilization efficiency between diets and parity groups was small in comparison to variation within parity groups.During weeks 21 to 44 of lactation the cows were at grass. In trial 2, but not in trial 1, cows previously given the low-energy diet gave less milk (1999 v. 2644 (P < 0·001) kg) but gained more live weight. There were also differences in the composition of milk produced in this period.

An examination of the effect of method and level of concentrate feeding on milk production in dairy cows offered a grass silage-based diet

“…Trials carried out on the effects of complete diet feeding on milk production have shown a similar range of results. Poole (1986) using either a high or low energy complete diet, reported a positive relationship between food intake and milk yield (r 2 = 0-58). The results of the present study, suggest that neither complete diet feeding nor increasing the frequency of concentrate feeding from twice to four times daily had any significant effect on milk yield.…”