Effects of stocking density on growth, physiological indices and expression of GH and IGF-I genes of largemouth bass Micropterus salmoides in in-pond raceway culture systems
NI Jinjin1, WANG Yuyu2, XU Gangchun1,2, NIE Zhijuan2, SUN Yi2, LI Quanjie2, XU Pao1,2*
1.National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306,China; 2.Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081, China
Abstract: Juvenile largemouth bass Micropterussalmoides with initial body weight of (4.50±0.23)g were reared in in-pond raceway culture systems (IPRS) which were consist of flow troughs divided into push water aeration zone, culture zone, and sewage collection area at stocking density of 0.2 kg/m3(SD1), 0.4 kg/m3 (SD2), and 0.6 kg/m3, SD3) with triplication. The growth, muscle nutrient, liver biological function and antioxidant capacity and brain growth hormone (GH) and hepatic insulin-like growth factor (IGF-1) of largemouth bass were analyzed in 30, 60, 90, and 120 days. Results showed that there were significantly higher body weight, weight gain and specific growth rate in the fish in SD2 group than those in the fish in SD1 and SD3 groups on day 30 (P<0.05). On days 60, 90 and 120, however, body weight, weight gain and specific growth rate were shown to be decreased with increasing stocking densities. The body crude lipid contents were found to be decreased with increase in stocking density, and the fish reared in the SD3 group had significant high levels of cortisol, glucose and triglyceride than those in the SD1 group on day 120 did (P<0.05). Serum lysozyme content was decreased with increasing stocking densities on days 60, 90 and 120. There were significantly higher relative expression levels of brain GH gene and hepatic IGF-I gene in SD2 group than that in SD1 group on day 30(P<0.05). There was significantly higher expressions of brain GH gene in SD3 group than that in SD1 group, while the expression levels of hepatic IGF-I gene were significantly lower in SD3 group than that in SD1 group on days 60 and 90(P<0.05), without significant difference in the expressions of GH and IGF-I genes on day 120 (P>0.05). In conclusion, largemouth bass reared at stocking density of 0.4 kg/m3 had better growth and health status before days 30, and after that, the fish reared at high stocking density in IPRS inhibited the growth and reduced immune function.
倪金金, 王裕玉, 徐钢春, 聂志娟, 孙毅, 李全杰, 徐跑. 养殖密度对池塘循环水养殖大口黑鲈生长、生理指标和GH、IGF-I基因表达的影响[J]. 大连海洋大学学报, 2020, 35(6): 805-813.
NI Jinjin, WANG Yuyu, XU Gangchun, NIE Zhijuan, SUN Yi, LI Quanjie, XU Pao, . Effects of stocking density on growth, physiological indices and expression of GH and IGF-I genes of largemouth bass Micropterus salmoides in in-pond raceway culture systems. Journal of Dalian Ocean University, 2020, 35(6): 805-813.