Effect of the type of carbohydrate on the concentrate of food intake of dairy cows on pasture

Two experiments were carried out to evaluate two sources of carbohydrate (fibrous and starchy) in concentrate supplement for high,producing dairy cows fed spring pasture. In experiment 1, 12 Friesian cows yielding 33.0 kg/d, were assigned to a 3x3 Latin square design with periods of 21 days. In experiment 2, 27 Friesian cows yielding 29.3 kg/d were assigned to a completely randomized design for 45 days. For both experiments, the treatments included: grazing alone (SP), grazing plus 6 kg/d of sugar beet pulp-based concentrate (Coseta) and grazing plus 6 kg/d of cereal-based concentrate (Cebada). The cows were supplemented twice a day and managed under a strip grazing system on pasture consisting mainly of perennial ryegrass. In Experiment I the concentrate diet contained 17.0% crude protein (CP) in the dry matter (DM), with 11.9% CP in Experiment 2. In experiment 1 herbage dry matter intake (10.7 kg/day), total dry matter intake (16.0 kg/day) and grazing behavior were similar for sugar beet pulp-based concentrate and cereal-based concentrate. In experiment 2 herbage dry matter intake (12.4 kg/d), total dry matter intake (17.4 kg/d) and grazing behavior were similar for the supplemented treatments. Unsupplemented cows had a higher herbage dry matter intake in experiment 1 (15.4 kg/day) and lower total dry matter intake (14.2 kg/day) in experiment 2, than the supplemented cows (P<0.05). The results suggest that carbohydrate source in concentrate supplement, did not affect food intake and grazing behavior of dairy cows on these experiments.