Effects of high potassium on in vitro fermentation pattern and CIS fatty acid metabolism of pasture grass

摘要

The effect of high potassium concentration on rumen fermentation and fatty acid biohydrogenation (BH) were investigated in a 6 hour in vitro incubation. A pasture grass sample with 26.3 g/kg dry matter (DM) of potassium was used as control. Supplemental levels of 10, .20 and 30 g/kg DM of potassium were added as potassium chloride. Results showed that high potassium concentration had no significant effects (P >0.05) on pH, molar concentrations of total or individual volatile fatty acids (VFA), concentrations of C_(18:0), C_(18:1) trans n, C_(18:1) cis 9, C_(18:2n-6), or BH of C_(18:2n-6) after incubation. However, concentration and BH of C_(18:3n-3) were significantly (P <0.01) affected by potassium supplementation. Both the 20 and 30 g/kg DM supplementation significantly (P <0.05 and P <0.01, respectively) decreased the concentration but increased BH of C_(18:3n-3). This preliminary study indicates that high concentrations of potassium alter rumen fatty acid metabolism. Further studies are neededto confirm this and investigate the possible causal mechanisms.