大西洋鲑幼鱼适宜投喂频率和胃排空研究

Studies on Feeding Frequency and Gastric Evacuation of Juvenile Atlantic Salmon(Salmo salar)

为探究大西洋鲑(Salmo salar)幼鱼的适宜投喂频率和胃排空规律,进行了养殖实验和胃排空实验。养殖实验设置了1次/天(F1组)、2次/天(F2组)、3次/天(F3组)、4次/天(F4组)和连续投喂(CF组)共5种投喂频率。胃排空实验采用连续测定胃含物的方法,用数学模型对胃含物数据进行拟合。研究表明:F1组日摄食率显著低于其余处理组(P<0.05),CF组日摄食率显著低于F3和F4组(P<0.05)。投喂频率从1次/天增加至3次/天,大西洋鲑幼鱼每日单次摄食率显著降低(P<0.05)。CF组饲料系数和死亡率显著高于其余处理组(P<0.05)。F2、F3和F4组末体质量、增重率、特定生长率和肥满度显著高于F1组和CF组(P<0.05),F1组末体长显著低于其余处理组(P<0.05)。CF组体质量变异系数显著高于F2、F3和F4组(P<0.05)。大西洋鲑幼鱼摄食后24 h胃排空,平方根模型对胃含物干质量的拟合度最高,通过该模型计算出大西洋鲑幼鱼饱食后4、6、12和24 h的胃排空分别为23%、33%、59%和92%,与大西洋鲑幼鱼在相同时间间隔下的摄食率一致。研究结果表明,投喂频率为2~4次/天时,大西洋鲑幼鱼具有稳定的摄食节律,其生长率和饲料转化率较高,生长差异小。低强度连续投喂方式不利于大西洋鲑幼鱼的生长和饲料转化。

To investigate the optimal feeding frequency and the gastric evacuation pattern of juvenile Atlantic salmon,a feeding experiment and a gastric evacuation experiment were carried out.For feeding experiment,juvenile Atlantic salmon individuals were randomly assigned to 5 feeding frequencies,i.e.,1 time/day(F1),2 times/day(F2),3 times/day(F3),4 times/day(F4)and continuous feeding(CF).For gastric evacuation experiment,gastric content of juvenile Atlantic salmon was serially analyzed and the weight of gastric content was fitted to mathematical models.Daily feed intake of F1 group was significantly lower than that of other groups(P<0.05),daily feed intake of CF group was significantly lower than that of F3 and F4 groups(P<0.05).Single meal size(%body weight per day)significantly decreased when feeding frequency increased from 1 to 3 times/day(P<0.05).Feed conversion ratio and mortality rate of CF group were significantly higher than those of other groups(P<0.05).Final body weight,weight gain rate,specific growth rate and condition factor of F2,F3 and F4 groups were significantly higher than those of F1 and CF groups(P<0.05)while final body length of F1 group was significantly lower than that of other groups(P<0.05).Coefficient of variation in weight was significantly higher in CF group than that in F2,F3 and F4 groups(P<0.05).Stomach empty finished 24 hours after satiation feeding.Square root model had the best fit for the gastric content in dry weight.It was calculated that gastric evacuation reached 23%,33%,59%and 92%in 4,6,12 and 24 h after a satiation feeding,which were in line with the single meal size of juvenile Atlantic salmon fed at the same intervals.The results suggested that 2 to 4 times/day showed a stable feeding rhythm resulted in an effective growth performance,feed efficiency and reduced growth heterogeneity while low-intensity continuous feeding pattern resulted in poor growth and feed efficiency.