In vitro protein protection of protein meals using Bioprotect and tannin extract from red grape marc

Protecting crude protein in the rumen may reduce extensive protein degradation and ammonia emission and increase available bypass protein in ruminants. This experiment was conducted to determine the effect of two Bioprotect (15 and 30 mL/kg dry matter (DM)) and two tannin extract (TE) (20 and 40 g/kg DM) inclusion rates on protein protection and in vitro fermentation characteristics of canola and soybean meals incubated for 24 h using an ANKOM in vitro gas production system. The treated canola and soybean meals produced lower soluble protein (fraction ‘a’) and larger slowly degradable protein (fraction ‘b’) than its untreated counterparts, p < 0.01. However, the 20 g/kg DM TE inclusion showed lowest effect on the amount of protein fractions ‘a’ and ‘b’ in both meals compared to their other treated counterparts. The increasing concentration of additives reduced the total volatile fatty acids (VFA), p < 0.001. The effects of additives differed between the treatments as 15 mL/kg DM Bioprotect and 20 g/kg DM TE did not affect the acetic to propionic acid ratio (A:P) and the time before gas production began. The increase in fraction ‘b’ and reduction in protein fraction ‘a’ confirm successful protein protection in this experiment. However, the extensive reduction in ammonia-N and in vitro degradable protein after using 30 mL/kg DM Bioprotect suggests possible toxicity to the microbes responsible for protein digestion in higher doses. Therefore, 15 mL/kg DM Bioprotect and 40 g/kg DM TE could be promising protein protection doses for in vitro experiments.