EFFECT OF ANAEROBIC FUNGI ON GLYCOSIDE HYDROLASE AND POLYSACCHARIDE DEPOLYMERASE ACTIVITIES, IN-SACCO STRAW DEGRADATION AND VOLATILE FATTY-ACID CONCENTRATIONS IN THE RUMEN OF GNOTOBIOTICALLY REARED LAMBS

Four naturally born lambs were placed in sterile isolators 24 h after birth, before the natural establishment of the cellulolytic microorgan isms. At the age of 4 weeks, a cellulolytic bacterial population of ap proximately 10(8) cells g(-1) of rumen contents was established by ino culation with a 10(-6) dilution of ruminal contents taken from an adul t sheep. A pure culture of Neocallimastix frontalis MCH(3) and Piromyc es communis FL was inoculated into the rumen 5 months after birth and a stable population of 10(3)-10(4) zoospores g(-1) developed; the cell ulolytic bacteria and fungi established populations in the 4 lambs tha t were similar to those observed in conventional animals. The presence of fungi led to an increase in the activity of most of the glycoside and polysaccharide hydrolases of the particle-associated microbial pop ulations. However, this effect was not acompanied by an increase in th e in sacco degradation of wheat straw or an increase in the volatile f atty acid concentration in the rumen contents.