An in vitro study was conducted to examine the effects of salinomycin (SL) and vitamin B
6 (pyridoxine hydrochloride) (B
6) 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 B
6 (10μg/ml) as additives. In P suspensions, SL and B
6 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 B
6 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 B
6, respectively, and the production of lysine increased by 81.4 and 39.4% (
p<0.001), respectively, during 12h incubation. When SL and B
6 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 B
6 were demonstrated to enhance the production of lysine from DAP-SI by mixed rumen protozoa, mixed rumen bacteria and their mixture in this study.
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