Effect of Formulated Feed and Chilled Trash Fish on Nitrogen and Phosphorus Budget in Ponds and Snakehead Channa argus Culture
In order to reveal changes in nitrogen and phosphorus budget in ponds and effect of different foods on Chinese snakehead Channa argus aquaculture.The overwintering snakehead fiingerlings with body weight of(310.25±27.72)g were raised in six ponds of the family farm in April at a stocking density of 5 000-5 300 ind./667m2 with triplication,and fed formulated feed and chilled trash fish.The growth of the snakehead and water quality in the trail ponds were regularly monitored,the nitrogen and phosphorus income and expenditure were calculated,and the ecological and economic benefits were evaluated in the ponds.The results showed that the snakehead had better growth rate in the chilled fish group than that in the formulated feed group in the early stage of culture,and poor growth in the middle and late stages of culture.Feed was the main input source of nitrogen and phosphorus,accounting for(88.66±2.06)％and(94.30±2.21)％of the total nitrogen input in formulated feed group and chilled fish group,and(94.96±2.13)％and(97.10±2.40)％of the total phosphorus income.Sediment was the main mode of nitrogen and phosphorus expenditure,accounting for(39.50±1.17)％and(48.90±1.60)％in the total nitrogen expenditure in the feed group and chilled fish group,respectively,and(43.23±1.53)％and(53.78±1.73)％of the total phosphorus expenditure.There were significantly higher absolute and relative utilization rates of nitrogen and phosphorus in the formulated feed group than those in the chilled trash fish group,with the nitrogen discharge coefficient of 7.06±0.34 and phosphorus discharge coefficient of 2.10±0.13,significantly lower than the 21.49±1.01 and 5.61±0.21 in the chilled trash fish group,and significantly higher profit and output-input ratios in the formulated feed group than those in the chilled trash fish group.In summary,the significantly better ecological and economic benefits were observed in the formulated feed group than those in the chilled trash fish group,and the feed formula of the snakehead should be continuously optimized,the chilled fish should be gradually banned to promote the development of healthy snakehead culture.
Ophiocephalus argusgrowthnitrogen and phosphorus budgetbreeding effecteconomic benefit
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