Gas production and nitrogen digestion by rumen microbes from deer and sheep

Abstract

The rates at which gas was produced by rumen microbes from red deer (Cervus elaphus) and sheep were measured in vitro. The objective was to test the hypothesis that the lower frequency of rumen eructation contractions in deer, compared to sheep and other ruminants, may have been associated with a lower rate of gas production. Two sheep and two deer were held indoors, given the same feed (chaffed lucerne hay) under an identical regimen, and rumen samples obtained on 5 consecutive days from each animal. Duplicate incubations were carried out on each day with a rumen liquor inoculum from each animal in a buffered medium and a ground lucerne hay substrate. The rates of gas production were monitored for 9 h and net ammonia production determined. There were no differences between species in rate of gas production but incubation with deer liquor resulted in a 27% greater (P < 0.01) net conversion of substrate nitrogen (N) to ammonia compared to sheep. Gas production averaged 0.23 ml/min per g substrate between 1 and 3 h of incubation and declined to 0.15 ml/min per g substrate after 7 h. Ammonia release over the incubation period resulted in 22 and 17% of the substrate N appearing as ammonia-N from deer and sheep incubations respectively (P < 0.01). The difference between deer and sheep in the frequency of rumen eructation contraction sequences does not appear to be related to rates of gas production in the rumen. © 1993 Taylor & Francis Group, LLC.