饲料脂肪水平对大规格松浦镜鲤越冬前后体质量损失、体成分及脂代谢基因表达的影响

Effects of dietary protein levels on weight loss,body composition and lipid metabolism gene expression of large-size Songpu mirror carp(Cyprinus carpio Songpu)before and after overwintering

为探讨饲料脂肪水平(3%、6%、9%、12%、15%、18%)对大规格松浦镜鲤越冬前后生长、体成分及脂代谢相关基因表达的影响,前期进行完大规格松浦镜鲤对饲料脂肪适宜需要量的研究试验后,在每一个网箱中保留规格齐整,质量为(609.70±49.93)g的20尾大规格鲤鱼进行越冬试验,共18个网箱(2.0 m×2.0 m×2.0 m),时间为2019年10月31日至2020年4月28日。越冬期间水温3~8℃。结果表明:6%脂肪组的质量损失率显著低于3%组及18%组(P<0.05)。各脂肪组间存活率无显著差异(P>0.05)。越冬后,18%脂肪组的肝体比显著高于3%、6%和12%脂肪组(P<0.05),各组间肝体比下降比无显著差异(P>0.05),以6%脂肪组为最低。6%脂肪组越冬后肌肉粗蛋白质含量最高,显著高于15%组和18%组,且其下降率为最低,显著低于3%组和18%组(P<0.05)。3%脂肪组的肌肉粗脂肪含量显著低于其余各组(P<0.05),6%组和9%组的肌肉粗脂肪下降比显著低于其余各组(P<0.05)。越冬后18%脂肪组的肝胰脏脂肪含量显著高于除15%组外的其余各组(P<0.05),其下降比亦显著高于其余各组(P<0.05)。3%组肌肉水分含量为最高,显著高于6%组(P<0.05),且其水分增加比亦为最高,显著高于其余各组(P<0.05)。脂肪合成相关的脂肪酸合成酶、乙酰辅酶A羧化酶及固醇调节元件结合蛋白的基因表达量均以6%组为最高,其中脂肪酸合成酶表达量显著高于其余各组(P<0.05),乙酰辅酶A羧化酶的基因表达量显著高于3%、15%及18%组(P<0.05)。脂肪分解相关的肉毒碱棕榈酰转移酶的基因表达量3%组和6%组显著低于其余各组(P<0.05)。越冬试验发现,6%脂肪组能够使体质量损失率及肥满度降低比最小化,在越冬后保持了较高的肌肉蛋白质和粗脂肪含量,使鱼体自身内源脂肪合成能力增强而分解能力减弱,更利于维持体质,便于越冬后机体代谢能力的恢复。

The study was conducted to investigate the effect of dietary lipid levels(3%,6%,9%,12%,15%,18%)on growth,body composition and gene expression related to lipid metabolism of large-size Songpu mirror carp(Cyprinus carpio Songpu)before and after overwintering.The trial was carried out after the study on dietary lipid requirement for large-size Songpu mirror carp.20 fishes were kept in original cage for overwintering experiment from October 31,2019 to April 28,2020.The water temperature was 3~8℃during the overwintering period.Results showed as follows:the weight loss rate of 6%group were significantly lower than 3%and 18%groups(P<0.05).There was no significant difference in the survival rate(SR)and decrease rate of hepatosomatic index(HSI)among all groups(P>0.05).The HSI of 18%group was significantly higher than 3%,6%and 12%groups(P<0.05).The content of crude protein in muscle of 6%group was significantly higher than that of 15%and 18%groups,and the decrease rate of the content of crude protein in muscle of 6%group was significantly lower than that of 3%and 18%groups(P<0.05).After overwintering,the content of crude lipid in muscle of 3%group was significantly lower than other groups(P<0.05).The decrease rates of the contents of crude lipid in muscle of 6%and 9%groups were significantly lower than those of other groups(P<0.05).The content of crude lipid in hepatopancreas of 18%group was significantly higher than those of other groups except 15%group,and the decrease rate of the content of crude protein in muscle of 18%group was significantly lower than that of other groups(P<0.05).The moisture in muscle of 3%groups were significantly higher than that of 6%group(P<0.05),the increase rate of the content of crude protein in muscle of 3%group was significantly higher than that of other groups(P<0.05).The gene expession of fatty acid synthase(FAS)in hepatopancreas of 6%group was significantly higher than other groups(P<0.05).The gene expession of acetyl-coa carboxylase(ACC)in hepatopancreas of 6%group was significantly higher than 3%,15%and 18%groups(P<0.05).The gene expession of carnitine palmityl transferase 1(CPT1)in hepatopancreas of 3%and 6%group was significantly lower than other groups(P<0.05).In conclusion,the overwintering trial indicated that 6%dietary lipid in the fortified feed before overwintering had the most beneficial effect on the safe overwinter of large-size Songpu mirror carp.For large-size Songpu mirror carp,6%dietary lipid could minimize the weight loss and decrease rate of CF,help the body to store more protein and lipid in muscle,and poccess the strong endogenous fat synthesis ability and weakened lipogenic capacity,which was beneficial to maintain the physique and facilitate the recovery of the metabolic ability of the body after overwintering.