Effects of dietary fat source and supplemental lysophosphatidylcholine on performance, immune responses, and ileal nutrient digestibility in broilers fed corn/soybean meal- or corn/wheat/soybean meal-based diets
Two separate experiments were conducted to investigate the effect of different fat sources and a supplemental exogenous emulsifier (lysophosphatidylcholine, LPC) on growth performance, antibody production titers, and ileal nutrient digestibility in broiler chicks fed with different basal diets. A total of 288 one-day-old Ross 308 chicks were used for each trial (6 dietary treatments based on 3 × 2 factorial arrangements of treatments in both trials) with 4 replicates of 12 birds each. Dietary treatments consisted of 3 different fat sources (soy oil, SO; soy free fatty acids, SFFA; and palm fat powder, PFP) and 2 LPC levels (0 and 0.1% of diet), which were evaluated with 2 different basal diets (corn/soybean meal-based diets in Exp. 1, or corn/wheat/soybean meal-based diets in Exp. 2). In Exp. 1, average daily feed intake (ADFI) was increased (P < 0.01) in birds fed PFP diets compared with those fed SO or SFFA diets. Although supplemental LPC decreased (P < 0.01) ADFI, the birds fed SFFA diets had the greater ADFI at the presence of LPC (fat source × LPC, P < 0.01). Dietary supplementation of LPC caused a 4.6% improvement (P < 0.001) in average daily weight gain (ADWG) and consequently improved (P < 0.01) feed conversion ratio (FCR). Supplemental LPC was more effective in increasing ADWG in SFFA-containing diets, resulted in a significant (P < 0.01) dietary fat source × LPC interaction. Dietary inclusion of LPC increased (P < 0.01) bursa weight and improved (P < 0.05) antibody production titers against sheep red blood cells and Newcastle disease virus during primary responses. Ileal digestibility of ether extract (EE) was improved (P < 0.05) in birds fed diets containing SO as compared with those fed PFP diets; dietary LPC supplementation, however, had no marked effect on ileal nutrient digestibility. In Exp. 2, ADWG was greater (P < 0.05) in birds fed SO-containing diets compared with PFP-supplemented broiler chicks. Furthermore, dietary supplementation with LPC improved (P < 0.05) FCR value by 2.1%. Relative thymus weight was greater (P < 0.05) in birds fed LPC-supplemented diets than those fed unsupplemented diets. Supplemental LPC increased (P < 0.05) Gumboro antibody titer, and the lowest antibody response was allotted to the birds fed PFP diets. The greatest (P < 0.05) EE digestibility was assigned to the birds fed SO and SFFA diets. The present findings showed that birds fed SFFA-containing diets had similar performance as SO birds, and supplemental LPC improved overall performance especially in SFFA-fed birds.