Effects of Lysine Cell Mass Supplementation as a Substitute for L-Lysine·HCl on Growth Performance, Diarrhea Incidence, and Blood Profiles in Weaning Pigs

SIMPLE SUMMARY: Lysine cell mass (LCM) is a potential protein and lysine source for pigs. However, the potential value of LCM as a lysine source for the swine diet has not been investigated. Therefore, this study was conducted to evaluate the effects of LCM as an alternative lysine source in diets for weaning pigs. In the first experiment, an increase in dietary LCM from 0 to 1% did not affect the growth performance and diarrhea incidence of weaning pigs. However, in the second experiment, increasing the level of LCM supplementation for replacing L-lysine·HCl from 0% to 100% quadratically decreased the growth performance of weaning pigs such that replacing 0 to 80% of L-lysine·HCl with LCM had no difference in the growth performance, whereas LCM supplementation with 100% replacement of L-lysine·HCl decreased the average daily gain and gain to feed ratio of weaning pigs. We concluded that LCM could be included in the diet for weaning pigs as a substitute of L-lysine·HCl up to 2.8% and 1.76% for phase 1 and phase 2, respectively, without negative impacts on the performance of weaning pigs. ABSTRACT: This study was conducted to evaluate the effects of lysine cell mass (LCM) as an alternative lysine source in diets for weaning pigs on growth performance, diarrhea incidence, and blood profiles. In experiment 1, a total of 200 weaning pigs, with an average body weight (BW) of 6.89 ± 1.04 kg, were allotted into one of five treatments with four replicates of 10 pigs per pen in a randomized complete block design (RCBD). The dietary treatments were composed of LCM supplementation (0, 0.25, 0.5, 0.75, or 1.0%) with partial replacement of L-lysine·HCl (0 to 0.8% for phase 1 diets and 0 to 0.07% for phase 2 diets). The BW and feed intake were recorded at the end of each phase (d 0 to 14 for phase 1, d 14 to 35 for phase 2), and diarrhea incidence was checked daily throughout the experimental period. Blood samples were taken from the jugular vein of pigs at 2 weeks and 5 weeks to determine the blood profiles of weaning pigs. In experiment 2, a total of 144 weaning pigs with an average BW of 6.44 ± 1.19 kg were allotted into one of six treatments with six replicates of four pigs per pen in RCBD. The dietary treatments were composed of LCM supplementation (0 to 3.5% for phase 1 diets and 0 to 2.2% for phase 2 diets) with replacement of L-lysine·HCl from 0 to 100%. In experiment 1, partial replacement of L-lysine·HCl with 0 to 1% LCM did not affect growth performance and diarrhea incidence of pigs. An increase in the LCM supplementation from 0 to 1% with partial replacement of L-lysine·HCl had no influence on the blood urea nitrogen concentrations, whereas it resulted in a linear decrease (p < 0.05) in the serum IgG concentrations for 5 weeks. In experiment 2, increasing the dietary level of LCM with replacement of L-lysine·HCl quadratically decreased (p < 0.05) ADG and G–F ratio for phase 2 and G–F ratio for the overall period such that 100% replacement of L-lysine·HCl with LCM decreased ADG and G–F ratio of weaning pigs. An increase in the LCM supplementation with replacement of L-lysine·HCl tended to decrease linearly (p < 0.10) the diarrhea incidence of weaning pigs for the overall period and linearly decrease (p < 0.05) the serum IgG concentrations for 2 weeks. In conclusion, partial replacement of L-lysine·HCl with LCM from 0 to 1% had no negative impacts on the growth performance, but 100% replacement of L-lysine·HCl with LCM decreased the growth performance of weaning pigs. Therefore, LCM could be included in the diets for weaning pigs up to 2.8% and 1.76% for phase 1 and phase 2, respectively, as a substitute for L-lysine·HCl without detrimental effects on the performance of weaning pigs.