LYSINE AND FAT SUPPLEMENTATION OF WEANLING PIG DIETS

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Abstract
Three experiments, each of 6 weeks duration, were conducted with 23-day-old pigs averaging 5.9 kg initial weight. Three and four successive 0.2% additions of L-lysine to a 0.45% lysine, 14.2% protein basal diet improved feed consumption, gain, and the efficiency of feed and energy utilization. Adding 5% fat to the diets resulted in greater responses in gain and feed intake and conversion with male than with female pigs. No difference was observed between Yorkshire and Lacombe × Yorkshire pigs. A calorie-lysine ratio of 4000-kcal digestible energy per kg per unit percentage lysine was shown to be adequate for maximum efficiency of feed utilization, but a ratio of at least 3500:1 was needed for maximum gains.Metabolism trials were conducted when pigs were 5 and 9 weeks of age. Supplemental lysine increased the digestibility of lysine and the retention of nitrogen. The nitrogen digestibility improved with age of both sexes, but lysine digestibility improved with aging of the male pigs only. More energy and nitrogen were digested and more nitrogen was retained from the diets by the Yorkshire than by the Lacombe × Yorkshire pigs, especially at 5 weeks of age. The addition of fat did not influence any of the metabolism measures. The better diets were compared with a 22% protein, 1.18% lysine practical prestarter. Results did not differ between the diets.