Response of Early-Weaned Pigs to Amino Acid Supplementation of Corn Diets

A total of 143 early-weaned Yorkshire and Hampshire × Yorkshire pigs was used in five growth trials to determine the effect of amino acid supplementation of all-corn diets. The addition of an array of essential and non-essential amino acids including asparagine, glutamic acid, threonine, isoleucine, methionine, valine, cystine, serine, glycine, histidine and phenylalanine in various combinations failed to improve weight gain or feed per unit gain above that obtained with only lysine and tryptophan supplementation. Glutamic acid, added at a level of 5.0% of the diet in one trial as a nonspecific source of N for nonessential amino acid synthesis also failed to improve performance above that obtained with corn supplemented with .30% L-lysine and 0.05% DL-tryptophan. Low biological availability of one or more amino acids in corn for the early-weaned pig, a difference in rate of absorption of crystalline amino acids as compared to amino acids released from corn protein, or a requirement for amino acids other than those normally considered essential are suggested as possible factors in the poor response to amino acid supplementation of a corn diet.