The effects of dietary supplementation with lysine and methionine on body and tissue composition in the pig

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Abstract
SUMMARY A feeding trial was conducted on 24 individually-fed pigs given either a diet containing plant protein with insufficient Iysine and methionine or the same diet with optimal Iysine and methionine levels. Supplementation of the diet with synthetic amino acids significantly improved daily live-weight gain, feed conversion, nitrogen balance, loin eye muscle area and total yield of lean muscle. Pigs receiving insufficient Iysine and methionine were characterized by lower haemoglobin and creatinine values accompanied by a decreased level of glutamic oxaloacetic transaminase. There were highly significant differences in the blood and liver Iysine levels of the two treatments, and significant differences in the fresh muscle and in the pressed muscle juice Iysine levels. The ratios between liver and blood Iysine levels and between dietary or muscle Iysine levels and % of nitrogen retention were calculated and found to be the same on both treatments. The accumulation of Iysine in liver and muscle was linearly related to the blood Iysine level and to N retention and Iysine intake.