Research Article: Combined effects of dietary soybean lecithin and different lipid sources on growth, fatty acid profile, immune response, and plasma biochemistry in juvenile Asian seabass (Lates calcarifer)

A six-week investigation was conducted to examine the interactive influences of dietary lipid sources and soybean lecithin (SBL) levels on some physiological responses of Asian seabass (Lates calcarifer) juveniles (۵۰.۲±۲.۳ g). A research design containing three SL levels, including ۰, ۲ and ۴%, and four lipid sources, including fish oil (FO), vegetable oils (VO, canola and soybean oils; ۱:۱), rendered animal fats (RAF, lamb and poultry oil; ۱:۱), and their mixture (MIX) (FO, VO, and RAF; ۱:۱:۱). Based on this twelve experimental groups were designed as follow, ۱) FO (FO without SBL), ۲) FO+۲ (FO+۲% SBL), ۳) FO+۴ (FO+۴% SBL), ۴) VO (VO without SBL), ۵) VO+۲ (VO+۲% SBL), ۶) VO+۴ (VO+۴% SBL), ۷) RAF (RAF without SBL), ۸) RAF+۲ (RAF+۲% SBL), ۹) RAF+۴ (RAF+۴% SL), ۱۰) MIX (MIX without SBL), ۱۱) MIX+۲ (MIX+۲% SBL) and ۱۲) MIX+۴ (MIX+۴% SBL). Asian seabass juveniles were distributed into thirty-six ۳۰۰-L container (۱۵ fish in each replicate) filled with ۲۲۰ L of sea water (۴۵.۰±۰.۵ g/L). The experimental diets were offered to fish three times daily (۲۷.۱±۱.۲°C). The lowest final weight was in VO group and the highest growth performance were in FO+۲, RAF+۲, RAF+۴, MIX +۲ and MIX+۴ groups (p<۰.۰۵). In addition, feed intake (FI) and feed conversion ratio (FCR) ratio decreased in fish fed VO diet, but SL supplementation increased FI and FCR values (p<۰.۰۵). The amounts of n-۳ / n-۶ polyunsaturated fatty acids (PUFA) ratio, long chain-PUFA in fish fed diets containing FO increased. Plasma total protein and globulin in fish fed FO, VO+۲ and RAF+۴ were higher than those fed VO and RAF+۲ diets. The highest and lowest plasma alternative complement activities were in FO+۲ and VO groups, respectively (p<۰.۰۵). The fish fed with VO and RAF+۲ diets had the highest and lowest plasma triglycerides levels, respectively. The highest and lowest plasma cholesterol were in RAF and FO+۴, respectively. The findings of this investigation showed that dietary FO replacement with mixture of various lipid sources and SBL supplementation at ۲% can improve growth, fatty acid profile and humoral immune responses in L. calcarifer juveniles.

کلیدواژه ها:

Alternative lipid sources ، Fatty acid profile ، Innate immunity ، Marine fish ، Soybean lecithin