THE EFFECTS OF FEEDING FREQUENCY OF CONCENTRATES AND FEEDING SEQUENCE OF HAY ON EATING BEHAVIOR, RUMINAL ENVIRONMENT AND MILK-PRODUCTION IN DAIRY-COWS

Two lactation trials were conducted with Holstein cows to assess the effects of varying the feeding frequency of concentrates, addition of long hay, and the sequence of hay and grain feeding on performance, rumen fermentation and eating behavior. Numbers of primiparous and multiparous cows assigned to repeated Latin square designs (4 x 4) were 8 and 12 for exp. 1 and 12 and 20 for exp. 2. Each experiment utilized four extra rumen-fistulated lactating cows to examine aspects of rumen metabolism. The four treatments applied in exp. 1 were (a) twice-daily feeding of concentrate, no hay; (b) thrice-daily feeding of concentrate, no hay; (c) hay offered 1 h before concentrate; and (d) hay offered 1 h after concentrate. Treatments in exp. 2 were similar, with the following exceptions: (b) concentrate six times daily; (c) hay 2 h before concentrate; and (d) hay 0.5 h after concentrate. In each treatment in both experiments, alfalfa silage was offered ad libitum. The average concentrate/forage ratio of the diets was 74:26 and 60:40 for exp. 1 and 2, respectively. In exp. 1, except for time spent eating and concentration of rumen propionate (increased with addition of 2 kg hay d-1, P < 0.05), treatments had no effect on dry matter intake, milk production and rumen metabolism. In exp. 2, inclusion of hay in the diet (3 kg d-1) increased DM intake (P < 0.001) and milk (P < 0.05), protein and lactose (P < 0.01) yields but decreased milk-fat test (P < 0.01). Hay also increased the ruminal molar proportions of propionate, butyrate (P < 0.05) and valerate (P < 0.001) and decreased acetate (P < 0.05), isobutyrate and isovalerate (P < 0.001). As in exp. 1, rumen ammonia N and pH were not affected by treatments. The effects of hay inclusion in the diet in exp. 2 are consistent with the high quality of hay used, which had a lower fiber content than the silage.