Effect of the level of feeding on the digestion of hay and carbohydrase activities in an artificial rumen

In two separate experiments, the effects of four and two (in duplicate) levels of feeding on the digestion of hay in an artificial rumen system (RUSITEC) were determined by measuring overall digestibility, short chain fatty acid production, gas production, various glycoside hydrolase activities, and hemicellulase activity. The level of feeding, which varied by up to a factor of four, had no effect on the overall digestibility of the hay. Increasing the level of feeding by a factor of four gave an approximately fourfold increase in the production of acetic, propionic, and butyric acids. It took about 2 days to attain these higher productions. The same increase in feed also gave an approximately fourfold increase in methane and carbon dioxide production, but the increase, especially in methane, was not fully sustained. The different levels of feeding had no effect on the activities of α- and β- d- glucopyranosidase , β- d- xylopyranosidase , and α- and β- d- galactopyranosidase . A fourfold increase in the level of feeding increased the hemicellulase activity by a factor of approximately two.