Limiting Amino Acids in Wheat Shorts Fed to Swine

One hundred and five rats and 48 Yorkshire pigs were used in a series of trials to determine the protein quality in wheat shorts. Supplementation of wheat shorts with the five calculated limiting amino acids followed by individual omission of each of these added amino acids indicated that threonine was first limiting and lysine and methionine second limiting for the rat. Supplementation of lysine and/or threonine for the pig showed equal limitation of these amino acids with respect to growth performance and fasting plasma urea nitrogen (PUN). However, post-prandial PUN, nitrogen balance and urine urea measurements all indicated that lysine was first limiting and threonine second limiting for swine. The protein in shorts showed an apparent digestibility of only 75% in swine.