绿鳍马面鲀幼鱼昼夜摄食节律及胃排空模型研究

Diet feeding rhythm and analysis of gastric evacuation associated mathematical models in juvenile Thamnaconus septentrionalis

中文关键词: 绿鳍马面鲀  摄食节律  饲料效率  特定生长率  胃排空率

英文关键词: Thamnaconus septentrionalis  Feeding rhythm  Feeding efficiency  Specific growth rate  Gastric evacuation rate

中文摘要:

      为探究绿鳍马面鲀(Thamnaconus septentrionalis)幼鱼昼夜摄食节律及胃排空模型，分别采用一次饱食投喂法(将一昼夜划分为8个时段，分别为06:00、09:00、12:00、15:00、18:00、21:00、00:00和03:00，每个时段作1个处理，每天每个处理饱食投喂1次)和分段式连续投喂法(将一昼夜划分为与一次饱食投喂法相同的8个时段，每天每个实验桶连续投喂8次)两种方法研究绿鳍马面鲀幼鱼的昼夜摄食节律，实验持续7 d。此外，分别测定绿鳍马面鲀幼鱼[体重为(4.28±0.46) g]饱食后0、2、4、6、8、10、12、14、16、20、24和28 h时的胃内容物湿重，并用线性模型、指数模型和平方根模型3种数学模型拟合了绿鳍马面鲀幼鱼的胃排空率。结果显示，(1)在两种投喂方式下，实验鱼均表现为24 h一周期的摄食节律。在分段式连续投喂方式下，摄食率在03:00、06:00、09:00和12:00无显著差异，在15:00达到峰值后急速降低(P<0.05)，并在00:00达到最低值；饲料效率与一次饱食投喂方式下的03:00、06:00、15:00和18:00投喂组无显著差异，特定生长率显著高于一次饱食投喂(P<0.05)。(2)在一次饱食投喂方式下，实验鱼在18:00后摄食率急速降低(P<0.05)，并在00:00达到最低值；实验鱼在09:00和12:00投喂组的特定生长率和饲料效率显著高于一天中的其他时间(P<0.05)，每天09:00~12:00时间段投喂绿鳍马面鲀幼鱼可显著提高其生长和饲料效率。(3) 3种模型中，胃排空率用平方根模型拟合得最好，方程为y0.5=2.802‒0.204t (R2=0.987)；根据平方根模型，胃内饲料在饱食投喂10 h左右完全排空，达到投喂前水平，80%胃排空时间为6 h。综合上述指标，建议在生产实践中每天09:00~15:00时间段饱食投喂绿鳍马面鲀幼鱼3次，每次间隔3 h。

英文摘要:

      To investigate the diet feeding rhythm of juvenile of Thamnaconus septentrionalis and gastric emptying model, a once-per-day satiation feeding treatment (one day was divided into eight time periods, each time period was used as one treatment, and the fish of each treatment were fed to apparent satiation once a day) and a continuous feeding treatment with fixed intervals (one day was divided into eight time periods, the fish in each tank were fed to apparent satiation, eight times a day) were conducted for 7 days. The experimental fish [(4.28±0.46) g] were removed at various intervals (0, 2, 4, 6, 8, 10, 12, 14, 16, 20, 24, and 28 h) after satiation feeding. The wet mass of the chyme was determined and the applicability of the three mathematical models (linear model, exponential model, and square root model) was compared by the fitness of gastric evacuation data in juvenile T. septentrionalis. The results showed that T. septentrionalis exhibit a 24 h diet feeding cycle under two feeding scenarios. The feeding rate under the segmental continuous feeding mode was not significantly different at 03:00, 06:00, 09:00, and 12:00, but decreased rapidly after reaching a peak at 15:00 (P<0.05), and at 0: 00 reached the lowest value (P<0.05). The feed efficiency was not significantly different at 03:00, 06:00, 15:00, and 18:00 in the once-per-day satiation feeding, and the specific growth rate was significantly higher than that of a once-per-day satiation feeding (P<0.05). (2) The feeding rate of experimental fish decreased rapidly after 18:00 in the continuous feeding with a fixed interval (P<0.05), and reached the lowest value at 00:00 (P<0.05). The specific growth rate and feed efficiency at 09:00 and 12:00 in the experimental fish were significantly higher than at the other times of the day (P<0.05), optimal feeding times in T. septentrionalis culturing were during 15:00~18:00. (3) Among the three models, the gastric emptying rate was best fitted the square root model, and the equation was y0.5=2.802‒0.204t (R2=0.987). According to the square root model, the feed in the stomach was fed for 10 h. The left and right sides were completely emptied to the level before feeding, and the 80% gastric emptying time was 6 h. Based on the above indicators, it is recommended to feed the T. septentrionalis 3 times every day during the production practice from 09:00 to 15:00, with an interval of 3 h.