Effects Of Different Diets On The Growth, Activities Of Digestive Enzymes And Nutrient Budgets Of Sea Cucumber (Apostichopus Japonicus)

The present study investigated budgets of the C, N, P nutrients of sea cucumber withdifferent body sizes feeding on different diets with various protein levels which were obtained bymeans of addition of six proportions of fishmeal (0、2%、5%、10%、15%、20%). The specificgrowth rate (SGR) and,digestive enzyme activities were tested and the contributions of differentfood components in the feed were examined using stable isotope analysis under different dietconditions. The main results are summarized as followed:1. Study on the C, N, P nutrient budgets of the sea cucumber with different bodysizes:The study was conducted to explore the relationship between the C、N、P nutrient budgets ofthe sea cucumber and the body sizes. Sea cucumbers with4different body weight,2.11±0.56g,5.24±0.43g,10.21±1.02g and15.09±1.29g were used in the present experiment. The resultsshowed that the C、N、P nutrient budgets was related to the body weight of sea cucumbersignificantly. The oxygen consumption rate (OCR), ammonium excretion rate (AER) andphosphorus excretion rate (PER) increased with the increasing body weights of sea cucumberwhile the oxygen consumption rate (OCR), ammonium excretion rate (AER), phosphorus excretionrate (PER) and scope for growth (SFG) of C、N、P nutrients per unit body weight decreased withthe increasing body weights.2Study on the effects of different protein contents in the feed on the C, N, Pnutrient budgets of the sea cucumberThe present study investigated the effect of different protein contents in the feed on the C、N、P nutrient budgets of the sea cucumber. The fishmeal contents of the sea cucumber feed used inthe experiment included0(A),2%(B),5%(C),10%(D),15%(E) and20%(F), respectively.The results showed that there was significant relationship between the C, N, and P nutrientbudgets and the protein contents. T\he feed intake rate (FIR) and faecal production rate (PPR) of sea cucumber increased and then decreased with the increasing protein contents, and was highestas the content of protein was18%. The oxygen consumption rate (OCR), ammonium excretionrate (AER) and phosphorus excretion rate (PER) increased with the increasing protein contents.Phosphorus excretion rate (PER), however, showed the insignificant difference after the content ofprotein was over23%. Ingestion rate (IR) of C increased first and then decreased with theincreasing protein contents and showed the insignificant difference to the protein contents after thecontent of protein was over18%while ingestion rate (IR) of N and P continuously increased.Scope for growth (SFG) of C、N、P nutrients showed the similar trend as ingestion rate, only hadinsignificant difference to the protein contents after the protein content was higher than23%.3Effect of different proportions of protein on the growth and activities ofdigestive enzymes of sea cucumbers Apostichopus japanicusThe present study investigated the effect of different protein contents in the feed on thegrowth and the activities of digestive enzymes of sea cucumbers Apostichopus japanicus. Thefishmeal contents of the sea cucumber feed used in the experiment included0(A)、2%(B)、5%(C)、10%(D)、15%(E) and20%(F), respectively. Samples of sea cucumbers were collected atthe initial time, week1, week2, week4, week8and week12during the experiment. The specificgrowth rate (SGR) and digestive enzyme activities were tested and the contributions of differentfood components in the feed were examined using stable isotope analysis. The results revealedthat the sea cucumbers feeding on diet D showed the highest SGR with insignificant difference tothe sea cucumbers feeding on diet C (P>0.05). The sea cucumbers in group F showed the lowestSGR among the6feed groups (P<0.05). Stable isotope analysis showed that the contribution offishmeal to the food of sea cucumber was highest in die D relative to other feed group (P<0.05).Sea cucumbers feeding on diet C showed the highest protease and amylase activity. The proteaseactivity continuously increased throughout the experiment while amylase activity increased at thebeginning of the experiment and decreased afterward. The results indicated that the sea cucumbershowed the best growth performance and digestive ability feeding on the feed containing5%~10%fishmeal.