Journal of Dalian Ocean University  2023, Vol. 38 Issue (6): 1003-1012 DOI: 10.16535/j.cnki.dlhyxb.2023-090 |
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| Effects of water temperature on gastric evacuation rate of mandarin fish Siniperca chuatsi fed formulated diet |
| WANG Fubao，DONG Junjian，SUN Chengfei，WANG Miao，CHENG Guangzhao，LU Maixin，YE Xing*
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| 1.Guangdong Special Aquatic Functional Feed Engineering Technology Research Center，Foshan Nanhai Jieda Feed Company Limited，Foshan 528211，China；2.Key Laboratory of Tropical &Subtropical Fishery Resources Utilization &Cultivation，Ministry of Agriculture and Rural Affairs，Pearl River Fisheries Research Institute，Chinese Academy of Fishery Sciences，Guangzhou 510380，China |
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Abstract In order to investigate the effects of water temperature on gastric emptying rate of mandarin fish (Siniperca chuatsi) fed formulated diet to determine the appropriate feeding frequency, two sizes of mandarin fish with body weight of (89.50±10.21)g and (246.65±11.34)g were reared in 0.5 m3 glass fiber reinforced plastic buckets and fed formulated diet at water temperatures of 18, 25, and 30 ℃. The moisture, wet and dry mass of the gastric contents were measured in the mandarin fish anesthetized by anesthetic MS-222 at 0, 2, 4, 6, 8, 12, 18, 30 and 48 h after satiation, and linear, exponential and square root mathematical models were used to fit the relative wet and dry mass of the gastric contents at different time to screen the optimal gastric emptying model and to calculate the optimal feeding frequency. The results showed that the moisture of gastric contents in both size fish was found to be increased rapidly at first, then increased slowly and remained stable, while the dry mass of gastric contents to be decreased continuously, with a trend of rapidly decrease (0-8 h) and then slow down (8-48 h) at different temperatures. The relative wet and dry mass of fish gastric contents in the same size fish were negatively correlated with temperature (18 ℃ group >25 ℃ group >30 ℃ group). At different temperatures, the nearly empty time or completely empty time of the gastric contents of all the groups were 48 h, except 30 h in the small size fish at 30 ℃. The variance analysis showed that the fish size had significant influence on gastric evacuation of the relative wet and dry gastric contents (P<0.01). Temperature also had significant effects on gastric content moisture, relative wet and dry mass (P<0.01), without interaction between size and temperature (P>0.05). There was more accurately fitting model reflecting the gastric emptying by dry mass than by wet mass, and the exponential model was shown to be more suitable to describe the gastric emptying characteristics of mandarin fish. The fitting model showed that the gastric emptying of 80% dry mass in small size fish took 17.43 h at 18 ℃, 12.70 h at 25 ℃ and 9.71 h at 30 ℃, 20.40 h, with at 18 ℃, 15.74 h at 25 ℃ and 13.19 h at 30 ℃ in large size fish. The gastric emptying time was found to be decreased with the increase in warming temperature while prolonged with the increase in fish size. It is suggested that the feeding frequency practically be reduced to once a day or even lower in winter due to low water temperature, and to increase to 2 to 3 times/d in summer. At the same water temperature, however, better aquaculture benefits can be obtained by appropriately increasing the feeding frequency for small size fish and decreasing the feeding frequency of large size fish.
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Published: 18 January 2024
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