草鱼高脂日粮磷酸二氢钙适宜添加量的研究

THE OPTIMAL SUPPLEMENTATION OF MONOCALCIUM PHOSPHATE AT HIGH FAT DIET OF GRASS CARP(CTENOPHARYNGODON IDELLA)

为探讨草鱼高脂(7%)实用日粮磷酸二氢钙(MCP)适宜添加量对草鱼生长性能、脂质代谢及抗氧化能力的影响,以磷酸二氢钙[Ca (H2PO4)]为磷源,配制含MCP分别为0(对照组)、1.0%、2.0%、3.0%和4.0%的5种等氮等能实用日粮,饲喂初始均重为(105.23±0.55) g的试验草鱼,每种日粮设置3个重复,每个重复15尾鱼,进行为期8周的养殖试验。结果显示:在高脂日粮中添加适宜的MCP可显著增加草鱼增重率(WGR)和全鱼磷含量,降低饲料系数(FCR)和脏体比(VSI)。以WGR、FCR和全鱼磷为观测指标,折线模型分析得出日粮MCP适宜添加量分别为3.26%、2.96%和2.63%;全鱼、内脏、肌肉和肝脏粗脂肪含量随日粮中MCP的增加呈先降后升趋势,而全鱼和肌肉粗蛋白含量则呈相反趋势;在MCP3.0%组,草鱼肠道淀粉酶、脂肪酶、胰蛋白酶活性,血清碱性磷酸酶(AKP)活性最高,血清甘油三酯、肝脏丙二醛含量,乙酰辅酶A羧化酶(ACC)活性最低;添加组血清总胆固醇含量均显著低于对照组(P<0.05),肝脏肉碱脂酰转移酶(CPT-I)活性随日粮MCP添加量增加而渐增。研究表明,草鱼高脂(7%)日粮中MCP适宜添加水平为2.96%—3.26%(饲料总磷1.43%—1.50%),该添加水平能促进草鱼对日粮中营养物质的消化利用,减少鱼体及肝脂蓄积,增加鱼体蛋白,提高抗氧化机能,促进生长。

An 8-week feeding experiment was conducted to evaluate the effects of different monocalcium phosphate(MCP)levels added into high lipid(7.0%)diet on grass carp(Ctenopharyngodon idella)growth performance,lipid metabolism and antioxidant activity.Five levels of MCP(0,1.0%,2.0%,3.0%and 4.0%)were added into high lipid diet,respectively,as basal diets to feed grass carp[initial body weight(47.51±0.52)g].Each treatment contained three replicates with 15 fishes per replicate.The results showed that the addition of suitable MCP in high-fat diets could significantly increase the weight gain rate(WGR)and the whole-body phosphorus of grass carp,as well as reduce the Feed conversion ratio(FCR)and Viscerosomatic index(VSI).Taking WGR,FCR and whole-body phosphorus as the observational indicators,the analysis of broken-line model showed that the appropriate amount of dietary MCP was 3.26%,2.96%and 2.63%,respectively.With the increase of MCP in the diet,the whole-body,viscera,muscle,and liver crude lipid content decreased first and then rose,but the whole-body and muscle crude protein had opposite trends.In the MCP3.0%group,grass carp intestinal amylase,lipase,trypsin,and serum alkaline phosphatase(AKP)had the highest activity,while serum triglyceride,hepatic malondialdehyde and acetyl-CoA carboxylase(ACC)were the lowest.Serum total cholesterol was significantly lower in the supplemented group than in the control group(P﹤0.05).Liver carnitine acyltransferase(CPT-I)activity increased with the increaseing dietary phosphorus.This study indicates that the optimal supplementation of MCP in grass carp high fat(7%)diets was 2.96%-3.26%(TP 1.43%-1.50%),and the appropriate level of MCP can promote the digestion and utilization of dietary nutrients,as well as reduce hepatic lipid accumulation.At the same time,it also increases protein and antioxidant capacity,and decreases lipid,which help promote growth.