Effects of Dietary Nitrogen Sources on Fiber Digestion and Ruminal Fluid Characteristics in Sheep Fed Wheat Straw

  • Tan, Z.-L. ;
  • Lu, D.-X. ;
  • Hu, M. ;
  • Niu, W.-Y. ;
  • Han, C.-Y. ;
  • Ren, X.-P. ;
  • Na, R. ;
  • Lin, S.-L.
  • Received : 2001.01.02
  • Accepted : 2001.04.27
  • Published : 2001.10.01


Fifteen Inner Mongolian wethers with permanent ruminal and duodenal cannulas were used to study the effects of dietary rumen-undegradable protein (RUP) to rumen-degradable protein (RDP) ratios or protein sources on fiber digestion in the gastrointestinal tract and ruminal fluid characteristics. Fiber digestion and ruminal fermentation were not affected (p>0.05) by dietary RUP to RDP ratios (from 1.54 to 0.72). Soybean meal supplementation improved ruminal digestion. Fish meal supplementation increased (p<0.05) the ruminal degradability of fiber. The different RUP to RDP ratios (from 1.54 to 0.72) did not influence (p>0.05) ruminal fluid pH, but there were differences (p<0.05) in ruminal fluid $NH_3-N$ concentration because of urea replacement. Soybean meal as a dietary protein source decreased (p<0.05) ruminal fluid pH and increased (p<0.05 or p<0.01) $NH_3-N$, acetate, propionate and butyrate concentrations in the rumen. Fish meal as a dietary protein source decreased (p<0.05 or p<0.01) ruminal $NH_3-N$ and acetate concentrations and increased (p<0.05) ruminal propionate concentration. It can be concluded that dietary protein sources have more significant effect on fiber digestion and ruminal fermentation than different dietary RUP to RDP ratios, when the dietary crude protein requirements of growing sheep are satisfied.


Protein Source;Fiber Digestion;Wheat Straw;Sheep

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