Influence of different diets on growth and body composition of sea cucumber Apostichopus japonicus cultured in cages

Apostichopus japonicus is a species of Phylum Echinodermata in the family Stichopodidae. It is found in shallow waters along the coasts of western North Pacific. Apostichopus japonicus is mainly distributed in Liaoning,Hebei and Shandong provinces in China. Apostichopus japonicus shows high nutritional and medical value,and it is an important aquaculture species in China. It is cultivated in shallow ponds in northern China like Liaoning and Shandong,while cage aquaculture is becoming popular in South China. In recent years,cage aquaculture techniques have been widely developed in Fujian province( mainly in Ningde sea area),where the production reached 18 000 tons in 2012. The cultivation of sea cucumber is a burgeoning aquaculture industry in Fujian. However,we are still lack of experience in feed choosing and application,which leads to the unstable quality of Apostichopus japonicus and poor culture benefits. In China,most of researches aim at nutritional requirements and the feed influence on the growth pond cultured Apostichopus japonicus. However,the influence of cage culture on growth and body composition of Apostichopus japonicus hasn't been reported. The study explored different influences of various feeds on Apostichopus japonicus growth and body composition. These data may provide additional support to develop and popularize cage aquaculture.A sea water monitor investigation was carried out in Dongan sea area( Xiapu county,Fujian province) in December 2013. During this period,water temperature was 11. 6- 16. 6 ℃,salinity was 27. 6- 29. 3,dissolved oxygen was 7. 92- 9. 59 mg·L- 1. 1 080 Apostichopus japonicus( initial average weight 51. 8 ± 6. 9g) chosen from Qingdao( Shandong province) were cultivated in 36 hoisting cages( size range was 72 cm × 39 cm × 31 cm,divided into six layers) after breeding,each cage has 30 sea cucumbers,meanwhile each layer has 5 individuals. Four groups were divided,each group has 3 parallels,and each parallel has 3 cages.Group A were fed with Laminaria japonica,group B with Laminaria japonica and fish surimi,group C with Laminaria japonica and Scallop visceral powder,and group D with formulate powder feed. The survival rate( SR),weight gain rate( WGR),special growth rate( SGR),viscera body wall ratio( VBWR),food conversion ratio( FCR),protein efficiency ratio( PER) and body composition were detected for 84 days. The data was analyzed using SPSS 19. 0.Results showed that SR and VBWR showed no significant difference( P 0. 05) between 4 groups,while WGR,SGR,FCR and PER varied in different groups. WGR and SGR varied between 79. 6 %- 172. 3 % and0. 70 % ·d- 1- 1. 19 % ·d- 1respectively. WGR and SGR showed no significant difference( P 0. 05)between group B and C. And WGR and SGR in group B and C was much higher than that of group A and D( P 0. 05). The lowest WGR and SGR appeared in group D. The lowest FCR( wet weight) appeared in group B,while the highest FCR appeared in group D. FCR showed significant differences( P 0. 05)between 4 groups. The highest PER appeared in group A,meanwhile the lowest PER appeared in group D.PER also showed significant differences( P 0. 05) between 4 groups. The body compositions were affected by different diets. The moisture content in group D was distinctly lower than that of the other groups( P 0. 05),while moisture content showed no significant difference( P 0. 05) between the other three groups.The crude protein content varied from 40. 0% to 48. 1%. The crude protein content in group C was distinctlyhigher than that of other groups( P 0. 05),while there was no significant difference( P 0. 05) between the other three groups. The crude fat content revealed apparent variation,the highest crude fat content appeared in group B,while the lowest crude protein content was in group C,there are significant differences( P 0. 05) between 4 groups. The ash content in group A is remarkably higher than that of the other 3groups( P 0. 05),while ash content in group B was distinctly higher than that of group C and D( P 0. 05). The ash content in group C and D showed no significant difference( P 0. 05).In all,sea cucumber Apostichopus japonicus cultured in cages grew best in group B fed with Laminaria japonica and fish surimiis.