Effects of wheat bran and bean hull as adsorption substrates for soybean molasses on the ruminal environment of dairy cows

We examined the effects of soybean molasses adsorbed to different substrates on the ruminal environment of dairy cows. Three Chinese Holstein dairy cows (all the same age, and three parity) with an average body weight of (500±50) kg were allocated three dietary treatments in a 3×3 Latin square design. The cows were fitted with the permanent ruminal fistula, the three experimental diets were similar except that some wheat bran (replaced 15% of corn meal by adsorbed soybean molasses with wheat bran) or soybean hull (replaced 10% of wheat bran and 5% corn meal by adsorbed soybean molasses with soybean hull). The results showed that the molasses that were adsorbed to soybean hull and wheat bran significantly increased the pH value of the rumen compared to the control group (P<0.01). However, there was no significant difference (P>0.05) between the pH values of the rumens of cows fed diets containing molasses adsorbed to soybean hull and wheat bran. The wheat bran diet resulted in significantly lower ruminal NH3-N concentrations than the control diet (P<0.05), however, no differences were observed between soybean hull and control diets (P>0.05). Furthermore, no significant differences (P>0.05) were observed in individual volatile fatty acid (VFA) (acetate, propionate, isobutyrate, butyrate, isovalerate, and valerate) concentrations or the acetate/propionate (A∶P) ratio between the control and treatment groups. However, the ruminal total VFA concentration in cows of the soybean hull molasses group did show a lower trend than that observed in the control group, whereas ruminal total VFA concentration in cows of the wheat bran molasses group had a tendency to increase. These results suggest that it would be efficient that feed soybean hull molasses to replace 15% of corn meal instead of 10% of what bran and 5% corn meal in dairy cattle. Molasses adsorbed to both wheat bran and soybean hull have the ability to maintain ruminal homeostasis, although wheat bran is a better adsorption substrate than soybean hull.