THE EFFECTS OF FEEDING FREQUENCY OF CONCENTRATES AND FEEDING SEQUENCEOF HAY ON EATING BEHAVIOR, RUMINAL ENVIRONMENT AND MILK-PRODUCTION INDAIRY-COWS

Two lactation trials were conducted with Holstein cows to assess the e ffects of varying the feeding frequency of concentrates, addition of l ong hay, and the sequence of hay and grain feeding on performance, rum en fermentation and eating behavior. Numbers of primiparous and multip arous cows assigned to repeated Latin square designs (4 x 4) were 8 an d 12 for exp. 1 and 12 and 20 for exp. 2. Each experiment utilized fou r extra rumen-fistulated lactating cows to examine aspects of rumen me tabolism. The four treatments applied in exp. 1 were (a) twice-daily f eeding 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 fol lowing exceptions: (b) concentrate six times daily; (c) hay 2 h before concentrate; and (d) hay 0.5 h after concentrate. In each treatment i n 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 conce ntration of rumen propionate (increased with addition of 2 kg hay d-1, P < 0.05), treatments had no effect on dry matter intake, milk produc tion 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 a nd lactose (P < 0.01) yields but decreased milk-fat test (P < 0.01). H ay also increased the ruminal molar proportions of propionate, butyrat e (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 inclusio n in the diet in exp. 2 are consistent with the high quality of hay us ed, which had a lower fiber content than the silage.