Effects of amprolium and monensin on oocyst discharge, feed utilization, and ruminal metabolism of lambs with coccidiosis
Horton, G.M.; Stockdale, P.H.
American Journal of Veterinary Research 40(7): 966-970
1979
ISSN/ISBN: 0002-9645 PMID: 507500 Document Number: 153047
Thirty female and 30 male crossbred lambs were used in 3 groups to determine the effects of feeding amprolium (10 mg/kg of feed) or monensin (11 mg/kg of feed) on naturally occurring coccidiosis. Measurements were made of 24-h oocyst discharge, feed intake and utilization, average daily weight gain, and digestibility under typical feedlot conditions. Ruminal volatile fatty acids and ammonia concentrations were determined in lambs with surgically prepared fistulas. All lambs had Eimeria spp. infection with an average discharge of 206.9 .times. 105 oocysts for the 24 h before the start of the experiment. Monensin and, to a lesser extent, amprolium were effective against E. ninakohlyakimovae and E. ahsata. Body weight gains and feed efficiency were higher (P < 0.05) for lambs fed amprolium and monensin. Digestion coefficients were significantly higher for lambs fed monensin than in those fed amprolium or in control lambs. Total ruminal volatile fatty acids and ammonia concentrations were not affected by either amprolium or monensin. Molar proportions of propionic acid were higher (P < 0.05) in the lambs given monensin, but amprolium had no effect on ruminal fermentation patterns. Amprolium and monensin were effective therapeutic agents against naturally occurring coccidiosis in feedlot lambs.