Study Optimal Lys To Trp Ratio In Weaned Piglets' Diets

The study was carried out to investigate the optimal Trp to Lys ratio in ideal amino acid pattern and the effect of decreasing the dietary CP content, different Lys level on performance and N balance in weaned piglets. Forty crossbred piglets [Yorkshire Landrace xDuroc] were allotted randomly by gender, litter and weight (average initial body weight of 11.36kg)into 20 groups and then distributed into five treatments: Diets lwas the positive treatment with the high CP content (phase â… , â…¡CP content 18.6%,17.2,respectively ); Diets2,3,4 were low protein treatment (phase â… , â…¡CP content 16.6%,15.2,respectively ) with different Trp/Lys ratios on the true digestible basis : 16, 18, 20, respectively; Diets 5 was anther positive treatment with the same content except additional 0.1% lys. Four replicates with two pigs per replicates in each treatments. Food intake, daily gain was recorded. The experiment last 28 days, dividing into 2 phase. Phase â… , â…¡ contained 1.00%, 0.90% true digestible Lys respectively .Metabolism experiment was conducted at 15 days, in which nitrogen retention, nitrogen digestion efficiency and utilization efficiency were evaluated.The research in low protein diets indicated that, judging by growth performance (mainly ADG & F/G),the optimal Trp to Lys ratio maybe 18. But judging by N balance trial (nitrogen retention, ABV) and BUN, the optimal Trp to Lys ratio maybe 16. So we infer that the optimal Trp to Lys ratio between 16 and 18. The research in high protein diets indicated that after adding 0.1 %lys-Hcl(Trp to Lys ratio was 16.7), growth performance and nitrogen metabolism was improved, supported that the optimal Trp to Lys ratio wasl7,just the means of 16 and 18. So we conformed that according to whole-stage performance and nitrogen metabolism, the optimum ratio of Trp/Lys on the true digestible basis was 17 for 11.35-23.6 kg piglets.