The Basic Research On The Relationship Between Intestinal Bacteria And Bait Conversion In Sea Cucumber

Apostichopus japonicus is a kind of marine organism with high economic value.In recent years,as people's demand for sea cucumber has increased,the sea cucumber aquaculture industry is in the ascendant.In the aquaculture system of sea cucumber,high-quality bait is needed to ensure the healthy growth of sea cucumber.However,due to the limited source of natural baits,the research of formulated food is not deep enough,limits the rapid development of sea cucumber aquaculture.Probiotics can not only improve the aquaculture water quality,regulate breeding organism immunity and digestive physiology,but also can be used as bait additives to improve the nutritional value of bait and promote the growth.The application of probiotics agents and sea cucumber aquaculture is an inevitable trend in the development of the industry.At present,the assessment of probiotics is uneven,closely related to the quality of probiotics,application methods,and the environment.In order to play its role better,it should be applied to actual production.This article intends to study the use of probiotics and intestinal flora,intestinal digestive enzyme activity,bait conversion rate and other aspects of comprehensive analysis,to explore the correlation between the transformation of barbed sea cucumber feed and intestinal bacteria.In the laboratory,through the feeding of sea cucumber probiotics feed and formulated feed,the water quality in the breeding process,the digestive enzyme activity in the intestine of sea cucumber,and the number of bacteria were detected.And analyze the diversity of intestinal bacteria and changes in crude protein,total sugar and free amino acids in the intestinal tract of sea cucumber.The main conclusions are as follows:(1)The quality of cultured water in the probiotics test group was better than that in the formulated test group.The ammonia nitrogen concentration was maintained at0.021-0.050 mg/L,and the nitrite nitrogen concentration was maintained at 0.012-0.03mg/L,while the ammonia group with the formulated food group up to 0.310 mg/L,nitrite nitrogen content reached 0.033 mg/L,far more than the probiotics group.(2)The probiotics feed can increase the SGR of sea cucumber,and increase the SGR from1.47%/d to 1.68%/d.(3)The addition of probiotics significantly increased the activity ofdigestive enzymes in the intestine of sea cucumber.The proteases,cellulases,alginases in the intestine and the amylase in the intestinal wall were greatly affected by the probiotics.After seven weeks of culture experiments,the protease activity of the contents of the anterior,middle and posterior parts of the intestine of sea cucumber reached 162.136 U/g,159.824 U/g,and 145.517 U/g.Compared with the first week,the protease activity increased by a maximum of 47.08%;The amylase activity of the intestinal wall of the intestine of the sea cucumber was 58.254 U/g,68.668 U/g,and75.126 U/g,respectively,and the amylase activity was increased by 36.98%.The cellulase activities of the contents of the anterior,middle and posterior parts were respectively 37.056 U/g,35.369 U/g,and 23.587 U/g,and the cellulase activity was increased by 31.29%.The contents of the front,middle and back of the intestine of sea cucumber were as follows: The alginase activity of the material was 40.558 U/g,37.748U/g,and 22.938 U/g,respectively,and the alginase activity in the intestinal contents was increased by a maximum of 33.42%.(4)Feeding of probiotics group significantly increased the conversion rate of crude protein and total sugar in the intestine of sea cucumber.The maximum conversion rate was 79.344% and 47.541%,respectively.The content of amino acid in the track increased with the increase of culture time,and the increase of the probiotics group was greater.(5)The number of bacteria in the intestine of sea cucumber was positively correlated with the conversion rate of bait.The addition of probiotics affected the number of bacteria and the structure of the bacteria in the intestine to a certain extent.The increase in the number of bacteria will promote the intestine of sea cucumber.Increased digestive enzyme activity,which in turn increases bait conversion.This study comprehensively analyzes the combined effects of the use of probiotics,and the overall evaluation of probiotics proves that the rational use of probiotics has a good effect on the culture.