OPTIMUM DIGESTIBLE LYSINE REQUIREMENT OF HIGH-LEAN GROWTH PIGS

Balance experiments on high-lean growth pigs were carried out to study the optimum requirement for ileal digestible lysine. In a preliminary experiment, ileal-cannulated barrows were used to determine apparent and true lysine digestibilities of barley, wheat and soybean meal. Usi ng these ingredients, six experimental diets were prepared in which th e lysine concentration ranged from deficiency to excess while the othe r essential amino acids were maintained at levels meeting or exceeding the requirement. The diets were fed to gilts of two weight classes (5 0 and 80 kg BW). Nitrogen balance and plasma urea level were the crite ria of response. True ileal digestible lysine requirement, estimated w ith a linear-plateau model, was 17.6 and 18.1 g/d for 50 and 80 kg pig s, respectively. Optimum digestible lysine : ME ratio for the two weig ht classes was estimated to be 0.72 and 0.58 g/MJ, respectively.