“…Mameesh et al(98) have reported, however, that penicillin was ineffective in altering the thiamine require ment of the rat.Protein sparing actionCombs(26) noted that while reports have varied as to whether antibiotic feeding enhances the efficiency of protein utilization by chickens and turkeys, it would appear that under certain conditions lower protein levels are satisfac tory when antibiotics are fed. More recently, West and Hill(163, 164) have reported on studies with broilers involving a total of more than 1,400 chicks and have concluded that in the presence of certain antibiotics (chlortetracycline, oxytetracycline, bacitracin and penicillin) ; optimal growth and feed efficiency were obtained with two percentage units less protein in the ration than was needed without an anti biotic .A number of reports(20,60,68,100) have appeared which indicate, in general, that from 2 to 4# less protein is needed in swine rations fortified adequately with one of the effec tive antibiotics-Other workers (68, 104, 105, 162) have failed to substantiate this finding, and Meade (104) sug gested that an antibiotic might spare protein indirectly by virtue of increasing the feed intake of pigs fed diets con taining lower levels of protein. Meade and Forbes.…”