The effect of the apparent ileal digestible lysine-to-energy ratio on growth rate and protein deposition in the body of growing pigs fed a wheat-rapeseed diet

摘要

The experiment was conducted on 20 pigs from 25 to 70 kg body weight (BW) to determine the optimal apparent ileal digestible lysine:metabolizable energy (Lys:ME) ratio in a wheat-rapeseed diet. Gilts (synthetic line 990) were allocated to 4 groups. Group 1 was fed a basal diet containing wheat and rapeseed meal (with 4.4 mM kg(-1) glucosinolates), without supplementation with any crystalline amino acids and was lysine deficient. Group 2 consumed a basal diet supplemented with 0.21% L-lysine . HCl, but was still deficient in comparison with the content of other essential amino acids. Group 3 was fed a diet supplemented with 0.42% L-lysine . HCl, 0.018% L-threonine, and 0.015% L-tryptophan. Group 4 received a diet supplemented with 0.65% L-lysine . HCl and 0.053% DL-methionine to maintain their mutual proportion of 100:32, however the concentration of these amino acids was in excess of the requirement. Supplementation of crystalline lysine to the basal diet was designed to contain a differential Lys:ME ratio: 0.34 (diet 1), 0.47 (diet 2), 0.59 (diet 3), and 0.71 g MJ(-1) (diet 4). The apparent digestibility of amino acids in wheat and rapeseed meal was determined in a separate experiment with surgically modified pigs. All diets were isoproteino (193 g kg(-1) DM) and isoenergetic (14.5 MJ kg(-1) DM). The methionine, threonine and tryptophan contents were close to the recommendations of CVB (1995) or were given in excess.