Performance of dairy cows fed grass-clover silage or biorefined silage pulp of grass-clover silage

Abstract: Grass and legumes can do ecosystem services like no other crops and are one of the biggest contributions to protein in dairy cow diets. Biorefining of silage, makes it possible to produce a high-fibre silage pulp (SP) that can be fed to ruminants and a local high-quality protein feed (press juice) for monogastric animals. Earlier studies have shown inconsistent effects on milk production when cows were fed SP. This master thesis will focus on investigation of intake, milk yield and milk composition in dairy cows fed a diet containing grass-clover silage or its biorefined SP from silage. The hypothesis was that the cows would have a similar milk yield when fed a diet containing SP compared to a diet containing grass-clover silage, when both diets are supplemented with concentrates. The experiment was conducted on the organic dairy farm of Sötåsen Agricultural High School, Töreboda, Sweden as a part of a larger EU-project, Green Valleys. The forage was harvested on the farm and stored in a bunker silo and then fed as silage or the silage was biorefined and then fed as SP to the cows. The SP contained higher dry-matter and neutral detergent fibre concentrations, but lower concentrations of crude protein and water-soluble carbohydrates compared to the silage. Seventy-two dairy cows were allocated to two groups and fed a diet containing either silage or SP, supplemented with concentrate, during the whole experiment that lasted for 120 days. The results showed a numerically higher forage dry-matter intake (DMI) for cows fed silage compared to SP. For cows fed SP, the milk yield and the energy-corrected milk (ECM) yield were generally lower compared to cows fed silage. Yields of milk protein and milk fat were lower for cows fed SP compared to cows fed silage, and the milk lactose yield showed a similar tendency as the milk fat and milk protein yields. The milk composition was not affected by the diets. Body-condition scores and body weights of the cows were not affected by the treatments.