Carbohydrase Activity of Rumen Entodinium Species from Sheep on a Starch-free Diet

Characterization of rumen ciliate community composition in domestic sheep, deer, and cattle, feeding on varying diets, by means of PCR-DGGE and clone libraries

The structure and variability of ciliate protozoal communities in the rumens of domestic New Zealand ruminants feeding on different diets was investigated. The relative abundance of ciliates compared with bacteria was similar across all samples. However, molecular fingerprinting of communities showed ruminant-specific differences in species composition. Community compositions of cattle were significantly influenced by diet. In contrast, diet effects in deer and sheep were weaker than the animal-to-animal variation. Cloning and sequencing of almost-full-length 18S rRNA genes from representative samples revealed that New Zealand ruminants were colonized by at least nine genera of ciliates and allowed the assignment of samples to two distinct community types. Cattle contained A-type communities, with most sequences closely related to those of the genera Polyplastron and Ostracodinium. Deer and sheep (with one exception) harboured B-type communities, with the majority of sequences belonging to the genera Epidinium and Eudiplodinium. It has been suggested that species composition of ciliate communities may impact methane formation in ruminants, with the B-type producing more methane. Therefore, manipulation of ciliate communities may be a means of mitigating methane emissions from grazing sheep and deer in New Zealand.

Activities of rumen micro-organisms in water buffalo (Bos bubalusL.) and in Zebu cattle

Two fistulated adult bulls of the Zebu breed and 2 fistulated adult buffalo steers were given a diet consisting of concentrate mixture (rice bran and cotton-seed cake in equal portions +2% calcium hydroxide + 1% common salt) and straw. This was later changed to an all-roughage diet of first cut berseem (Trifolium alexandrinum) Samples of the rumen contents were taken for determination of protozoal differential counts, concentration and relative proportions of volatile fatty acids (VFA), rate of cellulose digestion, fermentation rate, and net growth of rumen micro-organisms. Further data were obtained for the 2 buffalo steers fed sweet Sudan grass. When the feed consisted of concentrate and straw there were significant differences in the numbers of protozoa and in volatile fatty acid concentration in the 2 species of animals. Higher protozoal counts were observed in the rumen of bulls (7·2−8·1 × 105organisms/ml) than in the rumen of buffaloes (2·6−3·6 × 105organisms/ml). Greater concentration of VFA was found in the rumen of buffaloes (5·3−11·2 mequiv/100 ml rumen liquor) than in bulls (4·8−10·4 m-equiv/100 ml rumen liquor). With berseem, the concentration of VFA in the rumen was generally higher (6·73−11·0 m-equiv/100 ml rumen liquor) and the protozoal counts were lower (2·8−5·2 × 105organisms/ml) but there were no significant differences between bulls and buffaloes.

The rates of cellulose digestion and the maximum fermentation rates were similar in the 2 species indicating a microbial population of the same order. Higher rates of cellulose digestion and of maximum fermentation when the ration consisted of berseem than when it consisted of concentrate + straw indicated a higher concentration of micro-organisms, mostly bacteria.