Effects of the Level of Supplemental Flaked Rice Grain on Nutrient Intake, Rumen Fermentation and Nitrogen Balance in Dairy Cows

Abstract

The effects of varying proportions of flaked unhulled rice grain in the diet on nutrient intake, rumen fermentation and nitrogen balance in dairy cows were examined. Four Holstein dry cows were used for this study and they were allocated to the following 3 dietary treatments in turn, i.e. concentrates only (control: 0%), replaced 20% of concentrates with unhulled rice grain on a dry matter basis (20%), and replaced 40% of concentrates with unhulled rice grain (40%). There was no significant difference in dry matter intake among treatments. Starch contents were 14.8, 20.9 and 26.1% for the 0, 20 and 40% diets, respectively, but the digestibility did not significantly differ among diets. Although TDN content in the 40% diet was significantly lower than that in the 0% diet (P<0.05), there was no significant difference in TDN intake between diets. Ruminal pH, total VFA contents, VFA composition excluding propionic acid and ammonia N were not affected by the degree of supplementation with unhulled rice grain. In addition, the cows fed a 40% diet had a significantly lower percentage of fecal nitrogen to nitrogen intake than that under other diets (P<0.05), however there was no significant difference in microbial nitrogen synthesis per digestible organic matter intake in the rumen and blood urea nitrogen.
Therefore, these findings suggest that it is possible to substitute unhulled rice grain for up to 40% of ordinary rations in dry cows.