The objectives of this study was to evaluate the degradability and digestibility of crude protein (CP), rumen undegradable protein (RUP), and individual amino acids (AA) on six by-product feedstuffs (BPF) (rice bran, RB; wheat bran, WB; corn gluten feed, CGF; tofu residue, TR; spent mushroom substrate from Pleurotus ostreatus, SMSP; brewers grain, BG) as ruminants feed. Three Hanwoo steers (40 months old, 520 ± 20.20 kg of body weight) fitted with a permanent rumen cannula and T-shaped duodenal cannula were used to examine of the BPF using in situ nylon bag and mobile bag technique. The bran CGF (19.2%) and food-processing residue BG (19.7%) had the highest CP contents than other feeds. The RUP value of bran RB (39.7%) and food-processing residues SMSP (81.1%) were higher than other feeds. The intestinal digestion of CP was higher in bran RB (44.2%) and food-processing residues BG (40.5%) than other feeds. In addition, intestinal digestion of Met was higher in bran RB (55.7%) and food-processing residues BG (44.0%) than other feeds. Overall, these results suggest that RB and BG might be useful as main raw ingredients in feed for ruminants. Our results can be used as baseline data for ruminant ration formulation.

This study was conducted to investigate the effects on in situ ruminal degradation of feed protein sources (soybean meal, P-SBM; dried distillers grain with solubles, P- DDGS; wheat bran, P-WB) treated with protease as compared with conventional feed protein sources (soybean meal, SBM; dried distillers grain with solubles, DDGS; wheat bran, WB). There was no significant change in the chemical composition and amino acid profiles of enzyme treatment protein sources compared with the non-treated groups (p<0.05). But for treatment groups, the solid content and total amino acids were reduced by increasing the moisture content due to proteolytic conditions. On the entire incubation time in situ ruminal degradation rate of dry matter appeared higher in treatment groups compared to control groups (p<0.05), and that of the treatment groups suspended during 48 hours were in the order of P-SBM (97.70%), P-WB (74.26%) and P- DDGS (72.39%). In particular, DM degradation rate of enzyme treated DDGS significantly increased to 43.62%, 45.99%, 55.97%, 69.87% and 72.39%, respectively, incubated during 3, 6, 12, 24 and 48 hours in rumen (p<0.05). Also protein degradation rate of P-WB and P-SBM significantly decreased compared to their respective non-treated sources; however, by contrast, in DDGS it was increased. For P-SBM, protein degradation rate significantly decreased at 6 and 12 hours, and for P-DDGS it was increased at 3 and 6 hours of suspension times in rumen (p<0.05). In particular, protein degradation rate of enzyme treated group suspended for 48 hours were in the order of P-SBM (91.81%), P-WB (86.36%) and P-DDGS (58.87%). This result suggests that protease treatment of feed protein sources might be utilized to increase the bypass ratio into post-rumen for wheat bran, soybean meal, and to improve the utilization of feed protein.

The study was performed to evaluate the effects of soybean meal (T1) and corn distillers dried grains with solubles (DDGS, T2) hydrolyzed by microbial proteolytic enzyme of Protame® on milk production and protein contents in dairy cows. Total of nine Holstein cows (i.e., 1.67 ± 0.47 average parity and 23.7 ± 1.2 kg/d average milk yield) were randomly assigned to control, T1, and T2 (e.g., 3 animals per group) and treated for 4 weeks. Milk yield of 3 different groups was similar in the beginning of the study, however the milk yield of T1 and T2 treatment group had increased by 0.93 kg/d and 1.89 kg/d, respectively. Milk protein level of T2 treatment group was increased by 0.19% (e.g., 0.14 kg/d protein content), whereas there was no significant different in control and T1 group. In conclusion, blood metabolites were ranged in normal level, but BUN content was reduced from 19.03 mg/dl to 17.70 mg/dl in T2 treatment group. This result suggests that DDGS hydrolysate supplement efficiently increase milk yield and milk protein level as well as feed protein availability in dairy cattle.