金虎石斑鱼和珍珠龙胆石斑鱼幼鱼胃排空特征及消化酶活性

Gastric Evacuation and Digestive Enzyme Activity in Juveniles of Hybrid Epinephelus fuscoguttatus(♀)×Epinephelus tukula(♂)and Hybrid E.fuscoguttatus(♀)×Epinephelus lanceolatus(♂)

【目的】比较金虎石斑鱼(Epinephelus fuscoguttatus♀×Epinephelus tukula♂)(记作EFT)和珍珠龙胆石斑鱼(E.fuscoguttatus♀×Epinephelus lanceolatus♂)(记作EFL)胃内容物质量的变化特征,并确定其最优数学模型。【方法】选取遗传背景相近、养殖条件相同的EFT和EFL幼鱼,在水温(24.04±1.87)℃条件下一次性饱食投喂颗粒饲料,在摄食后测定两者胃内容物湿质量,分析胃排空特征,比较线性模型、指数模型和平方根模型对胃排空曲线的拟合程度,分析胃和肠中消化酶活性变化规律。【结果】EFT、EFL幼鱼摄食后胃排空特征均呈典型的先慢后快再慢型,拟合效果最优的模型均为平方根模型,两种鱼类胃内容物(Y)与摄食后时间(t)的回归方程分别为Y0.5=1.0586-0.0142 t(R^(2)=0.9018,P<0.0001)、Y0.5=0.9690-0.0187 t(R^(2)=0.8835,P<0.0001);随着胃排空程度增加,除EFT幼鱼肠淀粉酶、EFL幼鱼肠脂肪酶、肠糜蛋白酶及胃淀粉酶活性变化无明显差异外(P>0.05),其余指标均变化显著(P<0.05),且EFT幼鱼肠脂肪酶和肠糜蛋白酶活性均显著高于EFL幼鱼(P<0.05)。【结论】EFT幼鱼的摄食水平及胃排空率均大于EFL幼鱼,且在胃排空过程中EFT对蛋白质和脂质的消化吸收能力强于EFL幼鱼。

【Objective】In order to compare and study the variation characteristics of gastric contents and gastric evacuation rate in two hybrid groupers,namely Epinephelus fuscoguttatus(♀)×E.tukula(♂)hybrid(EFT)and E.fuscoguttatus(♀)×Epinephelus lanceolatus(♂)hybrid(EFL),and determine the optimal mathematical models.【Method】Half-sib families with similar genetic backgrounds and under the same breeding conditions were selected as research subjects.The feed pellets were fed with satiation,water temperature at(24.04±1.87)℃,and the wet weight of gastric contents was measured after feeding to analyze the gastric evacuation characteristics,and constructed the gastric evacuation curve of three mathematical models:linear model,exponential model and square root model.At the same time,the regularity of changes about the activities of digestive enzymes in the stomach and intestines was also detected and analyzed.【Result】The gastric evacuation characteristics of EFT and EFL after feeding were all a typical slow-fast-slow pattern.The square root models are all mathematical models with the best fitting effect on gastric evacuation curves of EFT and EFL,and the equations of their mathematical models are Y0.5=1.0586‒0.0142 t(R^(2)=0.9018,P<0.0001)and Y0.5=0.9690‒0.0187 t(R^(2)=0.8835,P<0.0001),respectively.With the reduction of gastric contents,the activities of digestive enzymes all changed significantly(P<0.05),except for the changes of intestinal lipase activity,intestinal chymotrypsin activity,gastric amylase activity in juvenile EFL and intestinal amylase activity in juvenile EFT.In addition,the activity of intestinal lipase and intestinal chymotrypsin in juvenile EFT were significantly higher than those in juvenile EFL(P<0.05).【Conclusion】The feeding intake and gastric evacuation rate of juvenile EFT are higher than those of juvenile EFL.Furthermore,the digestibility and absorption of protein and lipids of juvenile EFT was stronger than juvenile EFL during gastric evacuation.