Abstract
An in vitro study was conducted to examine the effects of salinomycin (SL) and vitamin B6 (pyridoxine hydrochloride) (B6) on the production of lysine from the three stereoisomers of 2, 6-diaminopimelic acid (DAP-SI) by mixed rumen protozoa (P), mixed rumen bacteria (B), and their mixture (PB). P, B, and PB were isolated from the rumen of goats given a concentrate mixture and lucerne cubes, separately incubated for 12h with and without DAP-SI (5mM) as a substrate and SL (5μg/ml) and/or B6 (10μg/ml) as additives. In P suspensions, SL and B6 reduced the amount of DAP-SI by 2.1 times (p<0.001, where p is probability) and 19.9% (p<0.05), respectively, and also increased the production of lysine by 2.4 times (p<0.001) and 26.8% (p<0.05), respectively, during 12h incubation. In B suspensions, the reductions of DAP-SI with a single addition of SL or B6 were 8.5% (p<0.001) and 2.7%, respectively, and lysine production increased by 54.3 and 32.9% (p<0.001), respectively, during 12h incubation. In PB suspensions, the reductions of DAP-SI were 21.9 and 11.7% (p<0.001) with a single addition of SL or B6, respectively, and the production of lysine increased by 81.4 and 39.4% (p<0.001), respectively, during 12h incubation. When SL and B6 were added together to the P, B, and PB suspensions, lysine production further increased by 12.3, 21.3, and 12.4% more than the cases of adding SL only during 12h incubation, respectively. SL and B6 were demonstrated to enhance the production of lysine from DAP-SI by mixed rumen protozoa, mixed rumen bacteria and their mixture in this study.
