Antibiotics in Rumen Digestion and Synthesis. II. The Effect of Aureomycin on the Concentration of Some Amino Acids and B Vitamins in the Rumen

Open Access
Publisher Website
Google Scholar
Abstract
Two fistulated steers were used to detn. the amts. of amino acids and B vitamins present in the rumen at 6 and 12 hours after feeding a ration of hay and corn. The ration was supplemented later with 0.5 and 1.0 g. of aureomycin daily to detn. the effect of the antibiotic on these constituents. The concentration of the 10 essential amino acids in the rumen 6 hours after feeding was less when 0.5 g. of aureomycin was fed. The data suggest that the rate of removal was accelerated. When 1.0 g. was fed, the rate of removal was only slightly faster than that obtained on the aureomycin-free ration, but there was an individual difference when either level was fed. Direct evidence of the synthesis of amino acids was lacking because the amts. in the rumen at the 6- and 12-hour collections could be accounted for from the amts. ingested in the feed. There was less riboflavin in the rumen when 0.5 g. of aureomycin was fed than when the aureomycin-free ration was fed. Synthesis of nicotinic acid was indicated during the 1st 12 hours after feeding the aureomycin-free ration, whereas both levels of the antibiotic tended to reduce the amt. of synthesis.