Abstract
The effect of monensin on ruminal characteristics of sheep was investigated. Eight rumenfistulated sheep were assigned to two treatments (monensi nadded and control). A bloat-producing diet of barley, soybean oil meal, alfalfa meal and salt was used as the basic ration. Monensin was added to the basic ration at the rate of 20ppm. Rumen fluid was collected 2hr. after morning feeding, and ruminal characteristics were investigated. Monensin reduced (P<0.001) the ingesta volume increase (IVI), tended to reduce stable IVI, and reduced (P<0.01) gas production of the rumen fluid during 2hr. after collection of rumen samples. These results suggest that monensin inhibits bloating. Ruminal pH value (P<0.05) and viscosity of cell-free rumen fluid (P<0.05) were raised, and water intake during 2hr. after morning feeding was reduced (P<0.05) by monensin treatment. The total count of rumen protozoa was reduced (P<0.05), and the genus Ophryoscolex was reduced remarkably (P<0.001) by monensin treatment. The total count of rumen bacteria was not affected. However, the proportions of Gram negative cocci, Gram variable cocci and Gram positive cocci tended to increase, and the proportions of Gram variable chained cocci, Gram positive chained cocci and Gram negative rods tended to decrease by monensin treatment.
