2002 Fiscal Year Final Research Report Summary
Study on the protein digestion and nitrogen metabolism of horses fed high-roughage diets
| Project/Area Number |
12460116
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Zootechnical science/Grassland science
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
TANAKA Keiichi Hokkaido Univ., Grad. School of Agr., Prof., 大学院・農学研究科, 教授 (30021710)
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| Co-Investigator(Kenkyū-buntansha) |
TANIGUCHI Kozo Hiroshima Univ., Fac. Of Biol. Prod., Prof., 生物生産学部, 教授 (30093777)
KOBAYASHI Yasuo Hokkaido Univ., Grad. School of Agr., Asso. Prof., 大学院・農学研究科, 助教授 (50153648)
HATA Hiroshi Hokkaido Univ., Field Scie. Center North. Bio Asso. Prof., 北方生物圏フィールド科学センター, 助教授 (30250492)
OBITSU Takehito Hiroshima Univ., Fac. Of Biol. Prod., Asso. Prof., 生物生産学部, 助教授 (30194632)
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| Project Period (FY) |
2000 – 2002
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| Keywords | horse / ileum cannulae / dietary protein contents / nitrogen accumulation / ferimentation in hindgut / ^<15>N ammonia nitrogen / free amino acids in plasma / essential amino acids |
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| Research Abstract |
Hokkaido native horses fitted with the cannulae in the endo of ileum were used in this study.
1) Effect of dietary protein contents on nitrogen metabolism of horses. Urea synthesis in the body and its transfer to digestive tract from the body, and urinary excretion of urea were increased with increasing protein intake. When protein intake was decreaed, most of nitrogen that transferred to digestive tract from the body were utilized for urea re-synthesis. This suggested that urea transfer to digestive tract made a contribution to urea utilization of horses, when protein intake was decreased.
2) Effect of dietary protein contents on feed utilization and fermentation of hindgut of horses. Crude protein digestibility and the rate of protein accumulation was increased with increasing protein intake. Total VFA and NH_3-N concentrations in the hindgut was also increased, whereas pH tended to be decreased. When dietary protein level was increased, protein digestibility in the small intestine was increased. Then, nitrogen flow into the hindgut was increased. NDF and ADF digestibilities, as well as DAPA concentration in urine were not affected by dietary protein levels.
3) Transfer into plasma amino acids from NH_3-N infused into the ileum of horses Ammonia labelled ^<15>N was infused into the ileum of hoses in order to investigate the fate of endogeneous ammonia translated into digestive tract. All bacterial amino acid-N in the colon contained about 1% of ^<15>N-nitrogen. Free essential amino acids in plasma, such as leu, ile, val, his, lys, phe, had higher ^<15>N. This suggested that a part of plasma amino acids originated from amino acids synthesized by bacteria in the colon of horses.
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