Effect of fibrous and starchy carbohydrates in concentrates as supplements in a herbage-based diet for high-yielding dairy cows.

Abstract

The effects of 2 concentrates composed of different carbohydrate sources (beet pulp vs. maize) on intake, digestibility, yield and composition of milk from high-yielding dairy cows given fresh herbage indoors was investigated. In 1988 two diets and in 1989 three diets were used with 9 cows/diet. In 1989 concentrates were supplied on an equal amount of DM and in 1989 on an equal amount of energy. The animals received the concentrates after milking time. In 1988 the experimental period lasted 8 wk and in 1989 10 wk. In 1988 intake of herbage DM tended to be higher on the maize-enriched diet, resulting in a significantly (P<0.05) higher intake of OM and energy. Nitrogen intake was also significantly (P<0.001) higher, but mainly as a result of an unintentionally high CP content of the maize concentrate. In 1988 and 1989 the apparent digestibility of N was significantly (P<0.05) higher on the starchy as compared with the fibrous diet. In 1988 the milk yield on the maize-enriched diet was significantly (P<0.05) higher than on the beetpulp-enriched diet, partly due to a higher intake of energy. In 1989 no significant effect of carbohydrate source on milk yield was observed. Milk fat concn. declined as the proportion of starch in the diet increased. Milk protein content was not significantly affected by the source of carbohydrate. (Abstract retrieved from CAB Abstracts by CABI’s permission)