Comparative investigation of salinomycin and flavophospholipol in sheep fed different composed diets

The effects of salinomycin and flavophospholipol, and their relationship wi th the diet, were studied in nine ruminally and duodenally cannulated wethe rs. Within the composition of the ration, the levels of rumen degradable pr otein (RDP) and non-structural carbohydrates (NSC) were changed (diet H: 74 % RDP and 38% NSC; diet M: 57% RDP and 32% NSC; diet L: 48% RDP and 23% NSC ). There was no clear treatment effect of flavophospholipol on propionate c oncentration. Salinomycin supplementation appeared to be more effective tha n flavophospholipol in the increase of propionate concentration at the expe nse of acetic acid. Salinomycin significantly reduced the ammonia concentra tion of the rumen fluid. Microbial N content of the duodenal digesta was si gnificantly lower when salinomycin was used. Salinomycin inhibited proteoly sis and reduced the efficiency of microbial protein synthesis. The effect o f salinomycin on ruminal N metabolism was independent of the composition of substrate. Unlike salinomycin, flavophospholipol tended to increase proteo lysis in the rumen and did not inhibit protein synthesis. The effect of sal inomycin on ruminal fermentation and the duodenal flow of nutrients were in dependent of substrate composition.