投喂频率对大西洋鲑生长和生理指标的影响

将270尾均质量约500 g的大西洋鲑随机分为5组,每组2个重复,分别以3次/d、2次/d、1次/d、1次/2 d、1次/3 d的投喂频率饱食投喂56 d,以研究投喂频率对大西洋鲑生长性能、消化率、激素水平和抗氧化指标的影响。试验结果表明,随着投喂频率的降低,大西洋鲑质量增加率和摄食量明显降低,1次/2 d试验组和1次/3 d试验组质量增加率较3次/d试验组分别显著降低50%和75%,摄食量显著降低53%和72%。饵料系数、死亡率、皮质醇和抗氧化指标呈先降后升的趋势;饵料系数和皮质醇2次/d试验组最低,1次/3 d试验组最高,较其他组分别高1.2～2.1倍和0.38～4.78倍。血浆生长激素和甲状腺激素与之呈相反趋势,2次/d试验组各项指标较好;各试验组消化率均呈升高—降低—升高的变化趋势,2次/d和1次/3 d试验组值较高。试验结果表明,500～900 g大西洋鲑的最佳投喂频率为2次/d,在此基础上提高或降低投喂频率均会对大西洋鲑造成应激,对生长和饲料利用率产生负面影响。

Effects of Feeding Frequency on Growth and Some Physiological Indices in Atlantic Salmon Salmo salar

Two hundred and seventy individuals of Atlantic salmon Salmo salar with body weight of 500 g were randomly allocated into 5 groups and fed three times (group Ⅰ), twice (group Ⅱ), once (group Ⅲ) per day and once every two days (group Ⅳ) or once every three days (group Ⅴ) with 2 replicates to investigate feeding frequency on growth performance, apparent digestibility, hormone level and antioxidant indices of Atlantic salmon for 56 days. It was found that the growth rate and food intake were obviously decreased with the decrease in feeding frequency, the weight gain rate being decreased by 50% in group Ⅳ and 75% in group Ⅴ, and the food intake being decreased by 53% in group Ⅳ and 72% in group Ⅴ compared with group Ⅰ. There was a first decrease and then increase in food conversation ratio, mortality, cortisol level and antioxidant indices, with the minimal food conversation ratio and cortisol level in group Ⅱ, and the maximal values in group Ⅴ, 1.2-2.1 times and 0.38-4.78 times higher than other groups, respectively. An opposite trend was observed in growth hormone and thyroid hormone levels, with the optimal indicators in group Ⅱ, and the apparent digestibility was fluctuated with higher values in group Ⅱ and group Ⅴ. The findings indicated that the optimal feeding frequency was twice a day for 500-900 g Atlantic salmon.