Journal of Animal Science, Vol 74, Issue 6 1336-1342, Copyright © 1996 by American Society of Animal Science

JOURNAL ARTICLE

Effect of fungal biomass in alfalfa hay on intake and total tract digestion in growing beef calves

C. V. Bossuyt, K. M. Wittenberg and G. H. Crow
Department of Animal Science, University of Manitoba, Winnipeg, Canada.

Two experiments were conducted to determine effects of fungal biomass (FB), as determined by glucosamine analysis, in alfalfa hay on intake and total tract digestion when fed to growing beef calves. Mycotoxins were not detected in hays used for these experiments. A feedlot trial using 40 weaned Angus calves (270.2 +/- 9.7 kg) showed that DM intake was not affected (P > .05) by FB content of the hay diets. No adaptation response was observed when animals with no previous exposure to molded feed were introduced to hay containing various levels of FB. Hematocrit and plasma cortisol levels were not affected (P > .05) by the presence of FB in the hay. Eight steers were used, in two 4 x 4 Latin squares, for intake and total tract digestibility determinations of two alfalfa hays having similar nutrient profiles but differ in FB concentrations. Hays were fed in long or chopped form. Level of FB did not affect (P > .05) DM intake or total tract DM digestibility. Neutral detergent fiber and ADF digestibilities were 5.4 and 3.7 percentage units higher (P < .05), respectively, for hay with a high vs low FB concentration. Forage chopping reduced (P < .05) DM, NDF, ADF, and CP digestibilities; the effect being similar for the two hay types tested. Results suggest that FB concentrations ranging from 2.9 to 5.5 mg/g of DM do not affect DM intake, however, nutrient digestion can be influenced by molding during field wilting or storage.