Abstract: 6 of Small Tail Han ewes, fitted with permanent duodenum and ileum canula, with the body weight of 55 kg were orally administered with formalin at the dose of 0（control period） and 0.9 mL/kg ration （experimental period） in the condition of feeding the roughage diet. The collection of the chyme of duodenum and ileum and the experiment of digestion and metabolism were done, to study the effect of oral administration of formalin on the digestion and metabolism of sheep. The results showed that the oral administration of formalin in sheep increased the voluntary intake by 13.0%（P<0.01）；increased the digested OM and cellulose in fore stomach by 21.9%（P<0.01）and 29.7%（P<0.01）respectively； increased the OM, crude protein, microbe protein, by-pass protein, total amino acid and lysine arrived at small intestine by 5.2%（P<0.01）,21.5%（P<0.01）,13.2%（P<0.05）,29.4%（P<0.05）,18.0%（P<0.05）and 21.8%（P<0.05） respectively； increased the OM, crude protein, total amino acid and lysine absorbed by small intestine by 52.1%（P<0.01）,34.7%（P<0.01）,34.5%（P<0.05） and 32.8%（P>0.05） respectively；increased the apparent digestibility of the DM, OM, crude protein and cellulose of diet by 9.2%（P<0.05），9.2%（P<0.05），4.6%（P<0.05） and 5.8%（P<0.05） respectively；increased the retention of the nitrogen, calcium and phosphorus by 28.3%（P<0.01），30.8%（P<0.01） and 9.5%（P<0.05） respectively. It is concluded that the oral administration of formalin of sheep fed with roughage diet increases the digestive ability of rumen, the intake, and the small intestine-absorbed nutrients, especially the amino acids, therefore modifies the nutritional status of sheep.

Key words: formalin; sheep; digestion; metabolism; intake