本研究旨在探讨热应激建鲤(Cypyprinus carpio var.Jian)饲料中吡啶甲酸铬的适宜添加量.试验选取初始均重为(32.88±0.17)g的建鲤360尾,随机分为6组(每组4个重复,每个重复15尾鱼),分别投喂在基础饲料中添加不同水平吡啶甲酸铬的试验饲料,各组饲料Cr3+理论添加量分别为0、300、600、900、1 200和1 500μg/kg.试验在室内可控温循环流水养殖系统中进行,驯化期10 d(26℃),正试期60 d("常温一高温一常温"应激模式:20 d,26℃;20 d,3l℃;20 d,26℃).结果表明:1)饲料中添加600和900μg/kg吡啶甲酸铬(以Cr3+计,下同)可显著提高建鲤的增重率和蛋白质效率,降低饲料系数(P＜0.05).与对照组相比,当添加量达到1 500μg/kg时,增重率下降3.4％(P＞0.05).随着饲料中吡啶甲酸铬添加量的升高,建鲤肝体比呈上升趋势,900、1 200和1 500μg/kg添加组肝体比显著高于对照组(P＜0.05).2)饲料中吡啶甲酸铬的添加量对建鲤肌肉粗脂肪、灰分和水分含量的影响不显著(P＞0.05),对肝胰脏粗脂肪含量也无显著影响(P＞0.05),但300和600μg/kg添加组肌肉和肝胰脏粗蛋白质含量较对照组显著升高(P＜0.05).3)饲料中添加600μg/kg吡啶甲酸铬可显著提高建鲤血清中白蛋白含量(P＜0.05),添加1 500μg/kg吡啶甲酸铬可显著降低血清总蛋白和白蛋白含量(P＜0.05),添加600、900、1 200和1 500μg/kg吡啶甲酸铬可显著降低血清中胆固醇含量(P＜0.05),添加900、1 200、1 500μg/kg吡啶甲酸铬可显著降低血清中甘油三酯含量(P＜0.05).综上所述,在饲料中添加600μg/kg吡啶甲酸铬(饲料中Cr3+实际含量为912.94μg/kg)有较好的抗热应激效果,可促进热应激建鲤生长并提高其肌肉粗蛋白质含量.%This research was conducted to investigate the optimal supplemental level of chromium picolinate for heat-stressed Jian carp ( Cyprinus carpio var. Jian). A total of 360 Jian carp with average initial weight of (32. 88 ±0.17) g were randomly divided into 6 groups with 4 replicates per group and 15 fish per replicate. Fish in the 6 groups were fed with the basal diet supplemented with different levels of chromium picolinate, and the theoretical supplementation levels of Cr3 + in the 6 experimental diets were 0, 300, 600, 900, 1 200 and 1 500 μg/kg, respectively. The experiment was carried out in indoor facilities with water recycling system which has a temperature control unit. The acclimatization period lasted for 10 d (26 ℃) and the trial period lasted for 60 d ( ' normal temperature - high temperature - normal temperature' stress model: 20 d, 26 t; 20 d, 31 ℃; 20 d, 26 ℃). The results showed as follows; 1) supplementation of 600 and 900 μg/kg chromium picolinate (calculated as Cr3 + , the same as below) in diet could significantly increase weight gain and protein efficiency, and decrease feed conversion for Jian carp (P <0. 05). Compared with the control group, weight gain rate of fish fed diets supplemented with 1 500 μg/kg chromium picolinate decreased by 3. 4% (P >0. 05). With the increase of chromium picolinate supplementation, the hepatosomatic index of Jian carp was increased, and had a significantly (P <0. 05) higher when fish fed the diets supplemented with 900, 1 200 and 1 500 μ/kg chromium picolinate. 2) The contents of ether extract, ash and moisture in muscle and hepatopancreas ether extract were not significantly affected by chromium picolinate supplementation (P > 0.05) , while the crude protein content in muscle and hepatopancreas in 300 and 600 μg/kg supplemental groups was significantly higher than that in control group (P <0. 05). 3) Supplementation of 600 μg/kg chromium picolinate could significantly increase the serum albumin content (P <0. 05) , while 1 500 μg/kg chromium picolinate could significantly decrease the contents of serum albumin and total protein (P <0. 05) , 600, 900, 1 200 and 1 500 μg/kg chromium picolinate could significantly decrease the serum cholesterol content (P <0. 05) , and 900, 1 200 and 1 500 μ/kg chromium picolinate could significantly decrease the serum tri-acyglycerol content (P <0. 05). It is concluded that the supplementation of 600 μg/kg chromium picolinate (measured value of Cr3+ is 912. 94 μg/kg diet) has a better anti-heat stress effect, which can improve growth and increase muscle protein content of heat stressed Jian carp.
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