Influence of an anaerobic fungal culture administration on in vivo ruminalfermentation and nutrient digestion

Experiments were conducted to study the effect of administration of anaerob ic fungal cultures or their enzymes on ruminal fermentation, microbial popu lations and enzyme activities in the rumen, and general nutrient digestion in sheep. Twelve mature sheep receiving 560 g of orchard grass hay and 240 g of concentrate per day were randomly assigned to three different treatmen ts with four sheep per treatment. Control (FM) animals received 200 mi of t he defined medium for fungal growth through rumen cannulae at 8.00 h each d ay las a control treatment without added fungal enzymes and viable cells). The second group of animals (FE) were given 200 mi of supernatant from fung al culture incubated with an anaerobic ruminal fungus for 7 days las a trea tment for fungal enzymes in cultures without viable fungus). The third grou p (FC) was administered with an anaerobic fungal culture incubated for 7 da ys las a direct-fed microbials (DFM) treatment with fungal enzymes and viab le cells). Animals were exposed to each treatment for 15 days before rumen collection and digestion trials began. Direct administration of cultures of a polycent ric fungal strain, Orpinomyces strain KNGF-2 isolated from a Korean native goat, to the rumen of sheep (FC) generally increased nutrient digestibility and nitrogen (N) retention resulting from an increase in numbers of bacter ia and fungi in the rumen and by altering the patterns of volatile fatty ac ids (VFA) production. However, administration of fungal enzyme (FE) failed to improve nutrient digestibility and N retention, and ruminal fermentation parameters. Results indicate that these proteins may be rapidly degraded b y ruminal microbes or that these enzymes could reduce the growth or activit y of ruminal microbes. These are the first report of the effect of DFM orig inating from an anaerobic fungal culture. Such a development is particularl y significant because this study demonstrates that the introduction of a mi croorganism with superior fibrolytic activity into the rumen can improve nu trient utilization in ruminants. (C) 2000 Elsevier Science B.V. All rights reserved.