Effect of monensin on rumen ciliate protozoa in sheep

Comparison of nisin and monensin effects on ciliate and selected bacterial populations in artificial rumen

The effect of daily supplementation of nisin (2 mg/L), monensin (5.88 mg/L) and nisin and monensin (2 + 5.88 mg/L) on ovine ruminal ciliates and bacteria was investigated using the artificial rumen RUSITEC. Major groups in RUSITEC were Entodinium spp. and Dasytricha ruminantium. The supplementation of nisin significantly increased the population of both major ciliate groups. The supplementation of monensin significantly decreased the population of both groups. The combined effect of nisin and monensin was similar to the effect of monensin. Monensin had strong antiprotozoic effects in contrast to the stimulatory effects of nisin. D. ruminantium followed by Entodinium spp. appeared more resistant to tested compounds than other rumen ciliates. Tested additives did not significantly influence the presence and growth of amylolytic streptococci and enterococci but nisin showed a tendency to decreasing the concentration of Escherichia coli and lactobacilli.

The effect of monensin on in vitro utilization of lactate in the rumen contents

The effect of monensin on the in vitro utilization of lactate in the rumen contents of a steer, cow and two wethers was investigated. The rate of the utilization of lactate in monensin-treated cultures was on average only two thirds of that found in cultures without monensin. Monensin tended to increase acetate and to decrease butyrate in cultures with lactate. After 11-week adaptation of a wether to monensin the inhibitory effect of ionophore persisted, being, however, less pronounced and without influence on the molar percentages of VFA. Effects of monensin reported here seem to be caused by its inhibiting action against rumen lactilytic protozoa. There were no significant differences between monensin from Elanco and the Czechoslovak analogue.