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以初始体重为(137.5±0.4)g的大黄鱼Larimichthys crocea为实验对象,在海水浮式网箱中进行为期8周的摄食生长实验,研究饲料中糖水平对其生长、饲料利用、血液生化指标和糖代谢酶活力等的影响,以确定大黄鱼的饲料糖需求量。实验饲料按等氮(粗蛋白质45%)等能(18 k J/g)设计,糖含量分别为1.75%、6.67%、13.64%、21.15%、26.69%和32.25%。结果表明随着饲料糖水平的升高,大黄鱼特定生长率(SGR)先升高后降低,当糖含量为26.69%时,SGR达最大值,显著高于糖含量为1.75%、6.67%、13.64%和32.25%处理组(P<0.05)。饲料效率(FER)和蛋白质效率(PER)均在糖含量为13.64%—21.15%时显著高于其他处理组(P<0.05)。随饲料中糖水平的升高,全鱼粗脂肪含量显著降低,在糖含量为32.25%时降至最低(10.56%),显著低于其他处理组(P<0.05)。肝体比和肝糖原含量均随饲料糖水平的升高而显著升高(P<0.05),在糖含量为32.25%时达到最大值,显著高于糖含量为1.75%和6.67%处理组(P<0.05)。随饲料糖水平的升高,血浆甘油三酯和胆固醇水平均显著降低(P<0.05),而血糖水平不受饲料糖含量的影响(P>0.05)。大黄鱼血清溶菌酶、脂蛋白脂酶和肝脂酶活性均随饲料糖水平的升高显著降低(P<0.05),而肠淀粉酶活性表现为先升高后降低,在糖含量为26.69%时,酶活力达到最大值。随饲料糖水平的升高,大黄鱼肝脏己糖激酶活性先上升后下降,在糖含量为21.15%时达到最大值,显著高于糖含量为32.25%处理组(P<0.05),而丙酮酸激酶活力在糖水平为32.25%时达到最大值,显著高于糖含量为1.75%和6.67%处理组(P<0.05)。用二次多项回归模型拟合特定生长率和饲料糖水平的关系,得到大黄鱼饲料中最适糖含量为22.7%。
Larvalichthys crocea, an initial body weight of (137.5 ± 0.4) g, was used as experimental object to study the effects of dietary carbohydrate levels on the growth, feed utilization, blood biochemical parameters And sugar metabolism enzyme activity, etc., to determine the demand for feed sugar of large yellow croaker. The experimental diets were designed according to isobaric (18 kJ / g) iso-nitrogen (crude protein 45%) with the sugar content of 1.75%, 6.67%, 13.64%, 21.15%, 26.69% and 32.25%, respectively. The results showed that the specific growth rate (SGR) of large yellow croaker increased first and then decreased with the increase of dietary sugar levels. When the sugar content was 26.69%, SGR reached the maximum, which was significantly higher than that of sugar content of 1.75% and 6.67% 13.64% and 32.25% treatment groups (P <0.05). Feed efficiency (FER) and protein efficiency (PER) were significantly higher than those of other treatments (P <0.05) when the content of carbohydrate was 13.64% -21.15%. With the increase of feed sugar, the crude fat content of whole fish decreased significantly (10.56%) when the content of sugar was 32.25%, which was significantly lower than that of other treatments (P <0.05). Hepatic body glycogen content and liver glycogen content were significantly increased with the increase of feed sugar levels (P <0.05), reached the maximum at 32.25% of sugar content, significantly higher than the sugar content of 1.75% and 6.67% treatment group (P <0.05). Plasma triglyceride and cholesterol levels were significantly decreased with increasing feed sugar levels (P <0.05), while blood glucose levels were not affected by dietary sugar levels (P> 0.05). The serum lysozyme, lipoprotein lipase and hepatic lipase activity of big yellow croaker decreased significantly with the increase of dietary sugar levels (P <0.05), while the intestinal amylase activity increased first and then decreased with the increase of sugar content (26.69% When the enzyme activity reached its maximum. With the increase of dietary sugar levels, the hepatic hexokinase activity of large yellow croaker increased first and then decreased, reaching the maximum value at 21.15% of sugar content, significantly higher than that of the control group with 32.25% sugar content (P <0.05) Kinase activity reached the maximum at 32.25% of the sugar level, significantly higher than that of 1.75% and 6.67% sugar groups (P <0.05). Using quadratic multiple regression model to fit the relationship between specific growth rate and feed sugar level, the optimum dietary carbohydrate content of big yellow croaker was 22.7%.