| The in-pond raceway system(IPRS)is an emerging breeding model in last decade,its characterized by increased yield,increased efficiency and environmental friendliness.However,less research on tilapia in IPRS.There are no systematic studies on adaptive research,stocking density,daily management,water quality changes,and aquaculture benefits.In the present study,exploring the adaptability of tilapia in IPRS.Comprehen-sive analysis of tilapia growth and physiological changes,assessing the appropriate cul-ture density of tilapia in IPRS.Efficient use of IPRS through twice a year farming.Com-parative analysis of the muscle quality of tilapia cultured in IPRS and traditional tilapia adult fish cultured in ponds.The main results were as follow:Part 1.Study of tilapia once a year farming in-pond raceway systemIn order to explore the culture effect of tilapia in-pond raceway system culture mode,study once a year farming in-pond raceway systemin 2017.The 19950,34713,specifica-tions for 3.5±0.11 g,and 40,166 tilapia species were respectively placed in three sinks,and 700 species of trout species and Macrobrachium rosenbergii were placed in ponds outside the sink.The water quality indicators and aquaculture production of the culture system were analyzed and determined in the study.The temperature of water was between17.5℃to 34.4℃,the Ph was 7.33 to 7.94,the DO was between 3.14 to 8.26 mg/L.The concentrations of ammoniacal nitrogen and nitrite were 0.11 to 2.07 mg/L and 0.004to 0.107 mg/L respectively,water quality meets the growth needs of tilapia;the output of the three sinks were 4481 kg,8796 kg and 10632 kg respectively,FCR were 1.19,0.95and 0.88,,and the average yield was 72.5 kg/m~2;The output value was 189 955.7 yuan per hectare and the profit was39673.2.7 yuan,and the return on investment was 21.39%.The results showed that it is feasible to tilapia ponds in aquaculture system culture.The experiment can provide reference for the adaptability research and promotion of tilapia in ponds aquaculture system culture.Part 2.Study of tilapia twice a year farming in-pond raceway systemTo achieve the efficient utilization of pond aquaculture system and reduce the risk of cultivation,the research of twice a year the cultivation of GIFT tilapia in-pond raceway was carried out for the first time in China.In the first breeding expiration weighing around36.6 grams were kept in two raceway for a duration of 122 days with the breeding density of per square of 184 and 274 fish,respectively.In the second breeding expiration,weigh-ing around 185.2 grams were kept in two raceway for a duration of 100days with the breeding density of per square of 154 and 215 fish respectively.Cultured Macrobrachium rosenbergii,Hypophthalmichthys molitrix and Aristichthys nobilis.around the pond.De-termined the water quality indicators during the breeding cycles.Analyzed and evaluated the farming situation and benefits after the expiration of the set time limit.The resultes showes that the survival rate of GIFT tilapia was 83.38%,the feed coefficient was 1.12,and the aquaculture production was 24 107 kilogrammes in the first breeding expiration.The survival rate of GIFT tilapia was 93.35%,the feed coefficient was 1.17,and the aq-uaculture production was 25 730 kilogrammes in the second breeding expiration.The aquaculture production around the ponds of Macrobrachium rosenbergii was 2 012 kilo-grammes,the Hypophthalmichthys molitrix and Aristichthys nobilis was 1 789 kilo-grammes and 801 kilogrammes respectively.For the breeding benefits,the average in-vestment and income was 452 566 yuan per square hectare and 655 099 yuan per square hectare,so the profit was 202 533 yuan per square hectare,that is the return on investment was 44.75%.This study suggest that the use of pond aquaculture system to carry out the cultivation of GIFT tilapia in twice a year can reduce the incidence of streptococcus,and thus improve the breeding efficiency,which can achieve the efficient utilization of the in-pond raceway.Part 3.Study on growth and physiological response of tilapia in pond aquaculture systemIn this study,the growth and physiological parameters were compared between GIFT tilapia cultured in a traditional pond and in an in-pond raceway system(IPRS)for 120days.For the traditional way,5 tails/m~2(the A group)were reared,while 184 tails/m2(the B group)and 274 tails/m~2(the C group)were cultured in an IPRS.The main objective of this study was to find the appropriate density of tilapia to be cultured in an IPRS.The results showed that after 120 days of culture,the body weight,specific growth rate and absolute growth rate of the B fish were significantly higher than those of the A and C fish(P<0.05).The survival rate,coefficient of variation of weight and feed coefficient rate of B and C tilapia were lower than those of the A tilapia.Compared with A fish at 30 days,the relative expressions of serum cortisol,serum alanine aminotransferase,lysozymal as-partate aminotransferase and hepatic Hsp70 mRNA were significantly increased in the B fish(P<0.05).After The levels of serum cortisol and glucose in the C fish were signifi-cantly higher after 120 days of culture than those in the A fish(P<0.05).Compared with A,the levels of SAA,LAA and hepatic Hsp70 mRNA expressions of the B fish were significantly higher after 60 and 90 days(P<0.05),while the level of triglyceride was significantly lower during the whole experimental period(P<0.05).The results implied that tilapia in the B group were stressed in the early stage of cultivation but gradually acclimated to the environment,while tilapia in the Cgroup were stressed for a relatively longer time.Taken together,this study demonstrated that the appropriate stocking density of tilapia cultured in the IPRS might be 180/m~2 or less in order for a better growth per-formance than in the traditional culturing mode.Part 4.Analysis of the Nutritive Compositions of tilapia in two different culture modesIn order to explore the muscle quality of tilapia adult fish cultured by IPRS,tilapia produced at a density of 184 tails/m~2 was compared with tilapia cultured in traditional ponds,and tilapia were cultured in two culture modes.Comparative analysis of muscle conventional nutrients,amino acid composition,amino acid score and muscle quality evaluation.The results showed that compared with traditional pond culture,the tilapia produced by IPRS showed a significant increase in fat content(P<0.05),a significant decrease in water content,no significant change in the total amount of amino acids,and the production of tilapia muscles by IPRS.The contents of proline(Pro)and glycine(Gly)were significantly lower than those in traditional pond culture mode(P<0.05),and the content of cysteine(Cys)was significantly higher than that in traditional pond culture mode(P<0.05).The essential amino acid(TAA)content is increased and the umami amino acid(DAA)content is lowered.From the aspects of EAA/TAA,EAA/NEAA,chemical score(CS),amino acid score(AAS)and amino acid index(EAAI),the tilapia score produced by IPRS is relatively high.In terms of muscle texture,the tilapia produced by IPRS has a relatively low hardness and an increased viscosity.The results showed that the tilapia produced in the two culture modes were of good quality meat products.The tilapia cultured by IPRS had higher nutritional value.The tilapia cultured IPRS tasted more delicious. |
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