Marker gene analysis was performed to assess the effect of energy level on the diversity and population density of methanogens in pig fecal material. Crossbred pigs were fed high or low energy level diets, a high-energy (HE) diet that satisfied daily gain at 1.2 kg, and a low-energy (LE) diet with amount of 0.6 times of the HE diet. Growth performance and short-chain fatty acid in feces were examined. Diversity of methanogen was analyzed by the α-subunit of methyl coenzyme-M reductase gene (mcrA) clone library from fecal DNA. The DNA copy numbers of mcrA were quantified by real-time PCR. There was no difference in the concentration and composition of short-chain fatty acid between treatments. Differences in the mcrA clone library were observed between HE and LE treatments (p < 0.05). Ninety-five percent of cloned sequence affiliated genus Methanobrevibacter in the feces of the pig regardless of treatments. During the experimental period, no significant difference in the proportion of copy numbers of mcrA against that of 16S rRNA gene of total bacteria was observed between treatments. In conclusion, feeding energy level affected composition of methanogens in the large intestine of the pig, while population density of methanogen was not affected.
ObjectiveHomoacetogens play important roles in the production of acetate in the large intestine of monogastric mammals. However, their diversity in the porcine large intestine is still unknown. Marker gene analysis was performed to assess the effects of energy level on the diversity and population densities of homoacetogens in porcine feces.MethodsCrossbred pigs were fed high or low energy-level diets. The high-intake (HI) diet was sufficient to allow a daily gain of 1.2 kg. The low-intake (LI) diet provided 0.6 times the amount of energy as the HI diet. Genetic diversity was analyzed using formyltetrahydrofolate synthetase gene (FHS) clone libraries derived from fecal DNA samples. FHS DNA copy numbers were quantified using real-time polymerase chain reaction.ResultsA wide variety of FHS sequences was recovered from animals in both treatments. No differences in FHS clone libraries between the HI and LI groups were found. During the experimental period, no significant differences in the proportion of FHS copy numbers were observed between the two treatment groups.ConclusionThis is the first reported molecular diversity analysis using specific homoacetogen marker genes from the large intestines of pigs. There was no observable effect of feed intake on acetogen diversity.
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