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.

ABSTRACT
 Ⅰ. INTRODUCTION
 Ⅱ. MATERIALS AND METHODS
  1. Animals and diets
  2. Feed samples collection, chemical composition andamino acid analysis
  3. In situ rumen incubation of tested feeds
  4. In situ intestinal incubation of tested feeds
  5. Calculations and statistical analysis
 Ⅲ. RESULTS AND DISCUSSION
  1. Chemical and AA composition of tested feeds
  2. In situ rumen degradation
  3. In situ mobile bag digestion in the rumen
  4. In situ mobile bag digestion in the intestine
  5. In situ mobile bag digestion in the total tract
  6. In situ mobile bag digestion in the rumen, intestine,and total tract
 Ⅳ. ACKNOWLEDGEMENTS
 Ⅴ. REFERENCES

• Youl Chang Baek(Animal Nutrition & Physiology Team, National Institute of Animal Science, Rural Development Administration)
• Jin young Jeong(Animal Nutrition & Physiology Team, National Institute of Animal Science, Rural Development Administration)
• Young Kyoon Oh(Animal Nutrition & Physiology Team, National Institute of Animal Science, Rural Development Administration)
• Min Seok Kim(Animal Nutrition & Physiology Team, National Institute of Animal Science, Rural Development Administration)
• Hyun jung Lee(Animal Nutrition & Physiology Team, National Institute of Animal Science, Rural Development Administration)
• Hyun jung Jung(Animal Nutrition & Physiology Team, National Institute of Animal Science, Rural Development Administration)
• Do hyung Kim(Department of animal science, Gyeongbuk provincial college)
• Hyuck Choi(Animal Nutrition & Physiology Team, National Institute of Animal Science, Rural Development Administration, Department of Pet Science, Seojeong college) Corresponding author