Effect of Graded Amounts of Aspergillus oryzae Fermentation Extract on Ruminal Characteristics and Nutrient Digestibility in Cattle

¹ Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan 84322-4815

Five nonpregnant and nonlactating Holstein cows fitted with rumen fistulas were assigned to each of five dietary treatments of 0, 1, 2, 4, and 6 g of an Aspergillus oryzae fermentation extract in a randomized block design. Diets were fed for a 21-d adaptation, followed by a 4-d collection period. Fecal grab samples were taken on d 1 to 3 of the collection period preceding each feeding. Volatile fatty acid concentration and pH were determined on rumen samples from 0 through 12 h of collection. Rumen samples were collected 3 h after the 0500 h feeding and analyzed for bacteria, fungi, and protozoa.

Digestibility of CP, ADF, and NDF did not differ among treatments. Concentration of ruminal NH₃ N was lower in animals fed 1 g/d compared with control and animals receiving 2,4, and 6 g/d of A. oryzae fermentation extract. Molar percentage concentration of isovaleric was higher in cattle fed 4 and 6 g/d of A. oryzae compared with the control-fed cattle. Rumen proteolytic bacteria (log₁₀ml) was lowest in cattle fed 2, 4, and 6 g/d of A. oryzae fermentation extract compared with control fed cattle.

Key Words: Aspergillus oryzae • nutrient digestibility • ruminal fermentation

Submitted on December 15, 1988
Accepted on March 22, 1990