Milk production and concentrations of blood metabolites as influenced by the level of wet distiller’s solubles in dairy cows receiving grass silage-based diet

Authors

• Pekka Huhtanen University of Helsinki, Department of Animal Science, SF-00710 Helsinki, Finland
• Harri Miettinen Valio, Research and Development Centre, Box 176, SF-00181 Helsinki, Finland

DOI: https://doi.org/10.23986/afsci.72448

Abstract

Twelve Finnish Ayrshire cows were used in a 4 x 4 Latin square design with 4-week experimental periods to study the effects of replacing increasing amount of barley with wet distiller’s solubles (WDS) on feed intake, milk production, digestibility and blood constituents. The four dietary treatments consisted of grass silage ad libitum and 7.8 kg dry matter (DM)/d of barley, of which 0 (WDSO), 1 (WDS1), 2 (WDS2) and 3 kg DM/d (WDS3) was replaced with WDS. Mainly because of a greater intake of concentrate with WDS containing diets silage DM intake varied quadratically (P<0.05) with increasing level of WDS with a minimum being observed with diet WDS1. The total DM intake (P<0.05), milk yield (P<0.05) and lactose yield (P<0.01) increased linearly with the level of WDS. Milk protein yield varied both linearly (P<0.05) and quadratically (P<0.05) with the level of WDS reaching a maximum with diet WDS2. WDS had no significant effect on milk fat or protein content but lactose content increased (P<0.001) with the level of WDS. The effects of the treatments on digestibility of dietary constituents were generally small, although in certain cases significant. Replacing barley with WDS increased linearly the plasma concentrations of butyrate (P<0.10), glucose (P<0.10), non-esterified fatty acids (NEFA) (P<0.05), and urea (P<0.001). Inclusion of WDS in the diet increased the postprandial peaks of plasma propionate, butyrate, insulin and urea, and decreased that of ketones (acetoacetate and betahydroxybutyrate). Based on the effects of WDS on the mean plasma concentrations and postprandial pattern of changes in the blood and plasma metabolites, it is concluded that feeding WDS as a replacement of barley most likely increased hepatic gluconeogenesis and urea synthesis. This conclusion is supported by the changes in the milk composition and in the relative yields of milk constituents with increasing rate of WDS inclusion.