In vitro rumen fermentation characteristics of goat and sheep supplemented with polyunsaturated fatty acids

Abstract

An in vitro gas-production study was conducted to compare differences in rumen fermentation characteristics and the effect of supplementation of 4% linseed oil as a source of polyunsaturated fatty acids on the rumen fermentation profile in rumen fluid collected from goats and sheep. Rumen fluid for each species was obtained from two male goats of ~18 months old and two sheep of similar sex and age fed the similar diet containing 30% alfalfa hay and 70% concentrates. The substrate used for the fermentation was alfalfa hay and concentrate mixture (30:70) without (control) and with addition of linseed oil. The experiment was a two (inoculums) × two (oil levels) factorial experiment, with five replicates per treatment, and was repeated once. Rumen fermentation characteristics, including pH, fermentation kinetics, in vitro organic matter digestibility (IVOMD), volatile fatty acid (VFA) production and microbial population were examined. Results of the study showed that gas-production rate (c), IVOMD, VFA production and population of total bacteria and two cellulolytic bacteria (Ruminococus albus and Butyrivibrio fibrisolvens) from rumen fluid of goat were significantly (P < 0.05) higher than those of samples from sheep. Irrespective of sources of inoculums, addition of oil did not affect fermentation capacity, IVOMD and total VFA production. The higher B. fibrisolvens population (associated with bio-hydrogenation) in rumen fluid of goat seems to suggest that polyunsaturated fatty acids are more prone to bio-hydrogention in the rumen of goat than in sheep. This assumption deserves further investigation.