Effect of dietary bacterial lysine by-product meal supplementation on growth performance and excretion of purine base derivatives in growing-finishing pigs

The present study was designed to test the hypothesis that bacterial lysine by-product meal (BLBM) as a substitute of soybean meal in the diet on equivalent crude protein basis can regulate growth performance and the excretion of purine base derivatives in growing-finishing pigs. One hundred Duroc x Landrance x Yorkshire crossbred castrated male pigs (41.7 +/- 3.9 kg body weight) were randomly allotted to 4 treatments with 5 replications (pens) per treatment, and 5 pigs per pen. Dietary treatments were: 1) CON (basal control diet), 2) BLBM-10 (BLBM replaced 10% crude protein in soybean meal), 3) BLBM-25 (BLBM replaced 25% crude protein in soybean meal), and 4) BLBM-50 (BLBM replaced 50% crude protein in soybean meal). In addition, two metabolism trials were conducted to determine the impact of BLBM on nitrogen metabolism and the excretion of purine base derivatives. Compared with the control pigs, BLBM-10 and BLBM-25 pigs had similar average daily gain (ADC), average daily feed intake (ADFI), and gain-to-feed ratio (G/F) during the growing period. The BLBM-50 treatment decreased ADC and elevated G/F during the growing and the whole period (P < 0.05). The BLBM-50 treatment had greater ADFI and G/F than other treatments during the finishing period (P < 0.05). The nitrogen digestibility and nitrogen biological value in pigs fed BLBM-10 and BLBM-25 diets were similar to the CON treatment, while those criteria in pigs fed BLBM-50 diets were lower than those on the CON treatment (P < 0.05). The serum urea nitrogen values increased in response to BLBM supplementation during the growing and finishing period (P < 0.05), and the pigs had the greatest urea nitrogen concentrations when they were fed the BLBM-50 diets (P < 0.05). The urinary excretion of purine base derivatives and the concentrations of uric acid, xanthine, and hypoxanthine in plasma increased with increasing dietary content of BLBM (P < 0.05). In conclusion, the nitrogen metabolism in growing-finishing pigs was unaffected when up to 25% of crude protein in soybean meal was replaced by BLBM. The excretion of purine base derivatives were increased by BLBM levels in diets. It is feasible that BLBM substitutes 25% of crude protein in soybean meal for growing-finishing pig diets. Crown Copyright (C) 2012 Published by Elsevier BM. All rights reserved.