S UPPLEE et al. (1942) showed that the pantothenic acid requirements of the pig depend on several factors, including stage of development, previous nutritional history and interrelationships with other nutrients. Rations of natural feedstuffs were found by McMillen et al. (1948) to be low or borderline in pantothenic acid for maximum growth of pigs. Luecke et al. (1949 and 1950) produced characteristic pantothenic acid deficiencies with both semi-synthetic and natural rations containing 3.4, 3.8 and 4.2 mg. of pantothenic acid per pound of ration in the absence of added vitamin BI.-and antibiotics. Vohs et al. (1950) found that 5 mcg. vitamin B12 per pound of cornsoybean oil meal ration were adequate for optimum growth in growingfattening swine. Using crystalline vitamin B t2, Richardson et al. (1951) reported the vitamin Ble requirements of young growing pigs to be 5 mcg. or less in the presence of antibiotics (40 mg. per pound of ration). They observed an interaction between antibiotics and vitamin BI.-. Yacowitz et al. (1950), working with chicks, found that vitamin B12 and pantothenic acid spared each other. Evans et al. (1951) found that in the absence of sufficient vitamin B12, pantothenic acid accumulates in the liver; indicating that vitamin B~e aids in the transfer of pantothenic acid from the liver for use elsewhere in the chick's body. Antibiotics have been found to increase rate of gain by various workers including Lepley et al. (1950), Catron et al. (1951), Speer et al. (1951) and Luecke et al. (1951). Swick et al. (1951) showed aureomycin and streptomycin to be superior to other antibiotics for increasing growth in pantothenic acid deficient rats.