饲料脂肪水平对白甲鱼幼鱼生长性能、体组成和血清生化指标的影响

摘要

本试验旨在研究饲料脂肪水平对白甲鱼幼鱼生长性能、体组成及血清生化指标的影响.选用初始体质量为(0.78±0.05)g的白甲鱼幼鱼900尾,随机分成6组(每组3个重复,每个重复50尾),分别饲喂豆油添加水平为0(对照组)、2％、4％、6％、8％和10％(实测脂肪水平为2.83％、4.52％、6.68％、9.14％、11.35％和14.07％)的试验饲料,养殖期为60 d.结果表明:随饲料脂肪水平的升高,白甲鱼幼鱼的增重率(WGR)、特定生长率(SGR)、蛋白质效率(PER)均呈现先上升后下降的趋势,饲料系数(FCR)呈现先下降后上升的趋势.饲料脂肪水平为11.35％时WGR、SGR达到最大(分别为362.98％和3.06％/d),显著高于除6.68％和9.14％组之外的其他各组(P＜0.05);饲料脂肪水平为9.14％时PER达到最大(3.70％),而FCR达到最小(1.34),显著高于/低于除11.35％组之外的其他各组(P＜0.05).白甲鱼幼鱼的肝体比则随饲料脂肪水平的升高而上升,6.68％、9.14％、11.35％和14.07％组均显著高于对照组(P ＜0.05).各组白甲鱼幼鱼的脏体比无显著差异(P＞0.05).通过二次回归分析可知,白甲鱼幼鱼WGR、SGR、FCR及PER最优时,饲料脂肪水平分别为10.12％、9.56％、9.42％和10.18％.随着饲料脂肪水平的升高,白甲鱼幼鱼全鱼及肌肉粗脂肪含量逐渐升高,而全鱼及肌肉粗蛋白质含量则呈先升后降的变化趋势.饲料脂肪水平对白甲鱼幼鱼全鱼及肌肉水分和粗灰分含量无显著影响(P＞0.05).随着饲料脂肪水平的升高,白甲鱼幼鱼的血清胆固醇(CHO)和甘油三酯(TG)含量先升高后降低,高密度脂蛋白胆固醇(HDL-C)和胆汁酸(TBA)含量以及谷丙转氨酶(ALT)、谷草转氨酶(AST)和碱性磷酸酶(ALP)活性逐渐升高,而低密度脂蛋白胆固醇(LDL-C)含量则逐渐降低.饲料脂肪水平为9.14％时,血清CHO含量达到最高,且与其他各组差异显著(P＜0.05);饲料脂肪水平为11.35％时,血清TG含量达到最高,且与其他各组差异显著(P＜0.05).由此得出,适宜的饲料脂肪水平可促进白甲鱼幼鱼的生长,提高其饲料转化率和免疫能力;饲料脂肪水平过高则可引起其肝损伤或组织病变.在本试验条件下,综合考虑生长性能、体组成及血清生化指标,白甲鱼幼鱼饲料中适宜的脂肪水平为9.42％ ～10.18％.%This experiment was conducted to study the effects of dietary lipid level on growth performance,body composition and serum biochemical indices of juvenile Onychostoma sima.A total of 900 juvenile Onychostoma sima with an average initial body weight of (0.78 ± 0.05) g were randomly assigned into 6 groups with 3 replicates per group and 50 fish per replicate.Fish in the 6 groups were fed experimental diets containing 0 (control group),2％,4％,6％,8％ and 10％ soybean oil (actual lipid levels were 2.83％,4.52％,6.68％,9.14％,11.35％ and 14.07％,respectively) for 60 days,respectively.The results showed that the weight gain rate (WGR),specific growth rate (SGR) and protein efficiency ratio (PER) were firstly increased and then decreased with the dietary lipid level increasing.Conversely,the feed conversation ratio (FCR) was firstly decreased but then increased.The WGR and SGR had the highest values (362.98％ and 3.06 ％/d,respectively) when the dietary lipid level was 11.35 ％,and were significantly higher than those in other groups except for 6.68％ and 9.14％ groups (P ＜ 0.05) ; the PER had the highest value (3.70％) and the FCR had the lowest value (1.34) when the dietary lipid level was 9.14％,and were significantly higher/lower than those in other groups except for 11.35 ％ group (P ＜ 0.05).The hepatosomatic index (HSI) was increased with the dietary lipid level increasing,and that in 6.68％,9.14％,11.35％ and 14.07％ groups was significantly higher than that in control group (P ＜ 0.05).No significant difference was found in viscerosomatic index (VSI) among all groups (P ＞0.05).Based on square regression analysis,the suitable dietary lipid levels were 10.12％,9.56％,9.42％ and 10.18％ when WGR,SGR,PER and FCR of Onychostoma sima were optimum,respectively.With the dietary lipid level increasing,the crude lipid content in both whole body and muscle was increased,while the crude protein content in both whole body and muscle was firstly increased and then decreased.Dietary lipid level had no significant effects on moisture and crude ash contents in both whole body and muscle (P ＞ 0.05).The serum cholesterol (CHO) and triglyceride (TG) contents were firstly increased and then decreased with the dietary lipid level increasing.The contents of high density lipoprotein cholesterol (HDL-C) and total bile acid (TBA) and the activities of alanine aminotransferase (ALT),aspartate aminotransferase (AST) and alkaline phosphatase (ALP) in serum were increased with the dietary lipid level increasing.At the same time,the serum low density lipoprotein cholesterol (LDL-C) content was decreased with the dietary lipid level increasing.The serum CHO content had the highest value when the dietary lipid level was 9.14％,and was significantly higher than that in other groups (P ＜0.05) ; the serum TG content had the highest value when the dietary lipid level was 11.35％,and was significantly higher than that in other groups (P ＜ 0.05).Results of the above show that suitable dietary lipid levels can promote growth,and improve feed utilization and immunity of juvenile Onychostoma sima.But it may cause liver damage or tissue lesions when the dietary lipid levels exceed a certain limit.Through comprehensive analysis of growth performance,body composition and serum biochemical indices,we suggest that the optimal level of dietary lipid for juvenile Onychostoma simax is 9.42％ to 10.18％ under this experimental condition.