The Lysine Requirement for the Growth of Swine

Abstract

Weanling pigs were fed rations containing: (A) 10.6% linseed meal protein supplemented with methionine and histidine; or (B) approximately 22% sesame meal protein supplemented with methionine and histidine; or (C) approximately 22% of a mixture of meat scraps, zein and wheat proteins which included added methionine, histidine and tryptophan. The effects of adding various levels of lysine to the basal mixtures were studied over a 4-week period. The minimum level of lysine which produced the maximum gain in weight and feed efficiency was considered as the lysine requirement. For ration A, containing 10.6% protein, the lysine requirement was 0.6% of the ration. When rations were fed which contained approximately 22% protein the lysine requirement increased to 1.2% of the ration. The difference in these requirements is largely eliminated if they are expressed in terms of their proportion to the protein in the rations. The lysine requirements of 0.6% and 1.2% of the ration correspond to 5.7% and 5.5% of the protein in the 10.6% and 22% protein rations, respectively. The digestibility of the lysine in basal rations B and C was determined and applied to the requirement of 1.2% of the 22% protein ration. The digestible lysine requirement for weanling pigs fed 22% protein then became 1.1% of the ration, or 5.0% of the protein in the ration. The weight range obtaining in the growth period to which these requirements apply was approximately 16 kg to 33 kg. The average daily gains of the pigs receiving optimum levels of lysine were 382 gm for those receiving 10.6% dietary protein and 488 gm for those fed the 22% protein diets.