饲料蛋白质和脂肪水平对中华鳖生长性能、肌肉质构指标及肝脏相关基因表达的影响

Effects of different protein and lipid levels on the growth performance,muscle textural parameters,and genes expression in liver of Pelodiscus sinensis

为研究饲料蛋白质和脂肪水平对中华鳖(Pelodiscus sinensis)的生长性能、肌肉质构指标及肝脏相关基因表达的影响,实验采用双因素3×2因子试验设计,制成蛋白质水平分别为40%、45%和50%,脂肪水平分别为6%和9%的6组试验饲料,饲喂均重为(293.11±7.84)g的中华鳖,8周后测定相关指标。结果显示:饲料蛋白质和脂肪水平对中华鳖存活率无显著影响,但对增重率、特定生长率、饲料系数和肝体比均有显著影响。随着饲料蛋白质水平的升高,增重率和特定生长率均显著升高,45%和50%蛋白组增重率和特定生长率显著高于40%组,45%组饲料系数显著低于40%组,50%组的肝体比显著高于40%组。饲料脂肪含量对中华鳖生长性能无显著影响,9%脂肪组的肝体比显著高于6%组。饲料蛋白质和脂肪水平对肌肉水分和粗灰分含量无显著影响,肌肉蛋白质含量随着饲料蛋白质水平的增加先显著升高,然后在45%时达到稳定水平。肌肉脂肪含量随着饲料脂肪水平增加显著升高。饲料蛋白质和脂肪水平对中华鳖四肢肌肉的回复性、弹性和凝聚性无显著影响,硬度、黏性和咀嚼性随着饲料蛋白质水平升高而显著升高,随着脂肪水平升高而显著下降。肝脏igf-I基因mRNA表达水平随着饲料蛋白质水平的升高而显著升高,9%脂肪组的肝脏igf-I和lpl基因mRNA表达水平显著高于6%组。综合中华鳖生长性能及营养品质的试验结果,温室养殖条件下,中华鳖饲料适宜的蛋白质和脂肪水平分别为45%和6%。

A 3×2 factorial design was used to estimate effect of dietary protein and lipid levels on growth performance,muscle textural parameters,and genes expression in liver of Pelodiscus sinensis[average initial weight of(293.11±7.84)g].Six experimental diets were formulated to contain three protein levels(40%,45%and 50%),each with two lipid levels(6%and 9%).Turtles were held in greenhouse and fed three times daily for 8 weeks.No significant difference was observed in survival rate(SR)among all the treatments.However,weight gain(WG),specific growth rate(SGR),feed conversion ratio(FCR)and hepatosomatic index(HSI)were significantly affected by dietary protein and lipid levels.WG and SGR of turtles fed with 45%and 50%protein were significantly higher than those of the 40%group;FCR of turtles fed with 45%protein was significantly lower than that of the 40%group;whereas,HSI of 50%protein group was significantly higher than that of the 40%group.No significant difference was observed in growth performance among all the treatments at different dietary lipid levels.The HSI increased significantly with increasing lipid levels.Muscle moisture and ash content were affected by neither dietary protein nor lipid level.With the increase of protein level,the crude protein contents of muscle were firstly increased and then reached to a stable level at 45%group.The lipid content of muscle increased significantly with increasing lipid levels.No significant difference was observed in resilience,springiness and cohesiveness of muscle among all the groups at different dietary protein and lipid levels.Hardness,gumminess and chewiness increased significantly with increasing dietary protein levels and decreased significantly with increasing dietary lipid levels.With increasing dietary protein levels,the mRNA levels of insulin-like growth factor-Ⅰ[DK](igf-I[DK])gene in the liver increased significantly.Turtles fed with 9%dietary lipid had significantly higher igf-I and lpl mRNA levels in liver than those of the 6%group.The results of this study indicated that diet containing 45%protein and 6%lipid was suitable for soft-shelled turtle in greenhouse.