The effect of supplementing highly wilted grass silage with maize silage, fodder beet or molasses on degradation of the diets and the efficiency of microbial protein synthesis in the rumen of sheep

Abstract

This study aimed at determining the efficiency of microbial protein synthesis (EMPS) in diets based on highly wilted grass silage (GS, 539 g dry matter (DM) per kg) with the supplementation of starch or water-soluble carbohydrates (WSC) rich feeds, i.e. maize silage (MS, 391 g kg-1 DM intake [DMI]), fodder beet (FB, 173 g kg-1 DMI) or molasses (M, 137 g kg-1 DMI). All the diets were made isonitrogenous by urea supplementation (14.0, 4.0 and 2.0 g per kg DMI in GS-MS, GS-FB and GS-M diets). In sacco determined crude protein (CP) and organic matter (OM) degradabilities were 756, 800, 778 and 814 (P0.05) among the diets (36.6, 35.1, 34.7 and 34.0 g microbial nitrogen per kg OM apparently digested in the rumen in GS, GS-MS, GS-FB and GS-M diets, respectively). The estimated metabolizable protein supply from GS, GS-MS, GS-FB and GS-M diets amounted to 97, 91, 93 and 86 g kg-1 DMI, respectively. Apparently, highly wilted GS containing a high concentration of WSC (91 g kg-1 DM) supports high EMPS in the rumen and this cannot be improved by the supplementation with starch or WSC rich feeds.

Keywords

• Sheep, Rumen, Microbial protein, Grass silage