The Effect of Environmental Temperature and Dietary Lysine Source and Level on the Performance and Carcass Characteristics of Growing Swine

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Abstract
Ten trials involving 168 individually-penned pigs were conducted in which pigs were maintained at three temperatures (10 vs 22.5C in trials 1 to 5 and 22.5 vs 35C in trials 6 to 10) and were fed one of three, corn-soybean meal based diets from 24 to 59 kg body weight. The diets consisted of 1) high protein, .9% lysine, 2) low protein, .75% lysine and 3) low protein + .15% crystalline lysine. Cold exposure (10 C) depressed efficiency of feed utilization, carcass length, leaf fat weight and percentage of lean cuts, whereas exposure to a warm environment (35 C) depressed live weight gains compared to those of pigs maintained at thermal neutrality (22.5 C). The effect of the dietary lysine level and source on the rate and composition of gain in the pig was influenced by the environmental temperature in which the pig was maintained. The dietary lysine level required to maximize growth rate wcs lower for pigs housed in the cold or warm environment compared to those maintained at thermal neutrality due to the effect of environmental temperature on the pig's voluntary intakes of lysine and metabolizable energy. The low protein, lysine supplemented diet, apparently due to its lower heat increment component, tended to be more efficiently utilized than the isolysine, high protein diet for tissue synthesis in pigs maintained in the warm environment but not in animals housed in the cold or thermal neutral environments. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.