Study On Replacement Of Fish Meal By Plant Protein In Practical Diet For Seplella Maindornl

This study was conducted to evaluate the potential for use of plant protein in practical dietfor Sepiella maindroni. Firstly, the effect of temperatures and pH value on activities of proteaseand amylase in stomach, pancreas, gastric cecum and intestine of cuttlefish Sepiella maindroniewere studied by means of enzyme analyses. Then, the nutrient digestibility of seven proteinfeed ingredients fish meal (FM), soybean meal (SM), expanded soybean meal (ESM),fermented soybean meal (FSM), peanut meal (PM), rapeseed meal (RM) and corn gluten meal(CGM) were determined using in vitro methods for Sepiella maindronie. Finally,based ondigestibility results of these protein feed ingredients, six isonitrogenous and isocaloricexperimental diets were formulated to evaluate the effects of replacing ESM with FM ongrowth performance, pepsin activity and liver biochemical indices of Sepiella maindroni. Theresults were as follows:Experiment1: The effects of temperatures and pH value on activities of protease andamylase in stomach, gastric cecum, pancreas and intestine of cuttlefish Sepiella maindroni (155±34g) were studied. The results showed that the activities of protease and amylase of Sepiellamaindroni were significantly affected by temperatures and pH value (P<0.05). The optimumpH values of stomach, pancreas, gastric cecum and intestine for protease were2.8,5.2,7.6and7.6and for amylase were5.2,6.8,7.6and7.6, respectively. The optimum temperature forprotease in stomach was35℃, whereas all in pancreas, gastric cecum and intestine were40℃,respectively. the optimum temperature for amylase was40℃in gastric cecum and others wereall30℃. The activities of protease in different digestive organs ofSepiella maindroni weresignificant difference (P<0.05). But the activities of amylase have on significant difference(P>0.05). The activities of protease in different digestive organs were in the order of pancreas(2399.9±184.6U/g)> gastric cecum (1430.8±184.6U/g)> intestine (726.9±86.5U/g)>stomach (150.5±4.0U/g). While the activities of amylase were pancreas (155.8±12.1U/g)>intestine (153.2±8.4U/g)> stomach (242.1±14.7U/g)> gastric cecum (142.6±4.0U/g). Theactivities of protease were significantly higher than amylase in all digestive organs of Sepiellamaindroni (P<0.05).Experiment2: The digestibility of seven proteins feed ingredients were determined usingin vitro method in stomach, pancreas, gastric cecum and intestine of cuttlefish Sepiellamaindroni. The results showed that the order of digestibility of different digestive organs fordry matter and crude protein was intestine> pancreas> stomach> gastric cecum. The order ofdigestibility of dry matter was SM (40.6%)> FM (35.3%)> FSM (32.1%)> ESM(29.2%)>PM (26.9%)> RM (26.7%)> CGM(12.3%), while the order of digestibility of crude proteinwas SM (39.7%)> FM (35.0%)> FSM (33.3%)> ESM (31.8%)> PM (23.8%)> RM (23.0%)> CGM (13.1%). The digestibility of dry matter and crude protein of SM, ESM and FSM werecomparable to FM. These results suggest that the SM, ESM and FSM have great potential interms of replacement of fish meal in practical diet for Sepiella maindroni.Experiment3: A53-day feeding trial was conducted to evaluate the effects of replacingESBM with FM on growth performance, pepsin activity and liver biochemical indices ofcuttlefish Sepiella maindroni. Six isonitrogenous and isocaloric experimental diets wereformulated. The control feed was formulated to contain69.1%fish meal (Diet0), whereas in theother five feeds ESMB was included at5.33%,10.62%,15.84%,21.05%and26.20%toreplace5%,10%,15%,20%and25%with FM protein (Diet1to Diet5respectively). Each dietwas randomly assigned to triplicate groups of Sepiella Maindroni (initial body weight of1.34±0.03g). The results showed that there were no significant differences on growthperformance and survival rate of cuttlefish when the ESBM replacement was less than15%ofFM protein, however, high substitution level can inhibit the growth and decreased survival rateof cuttlefish. The survival rates of cuttlefish significantly decreased with increasing dietaryESBM levels (P<0.05). There were no significant differences in body crude lipid, ash,Hepatosomatic index (HSI) and condition factor (CF) among the treatments, while body crudeprotein content of cuttlefish fed diet contained15-25%substitution of FM protein withESMB protein were significantly lower than those fed other diets. Activities of pepsin,glutamic-pyruvic transaminase (GPT), glutamic-oxalacetic transaminase (GOT), alkalinephosphatase (AKP), acid phosphatase (ACP), Catalase (CAT) and superoxide dismutase (SOD)in liver decreased with increasing dietary soybean meal levels. In conclusion, FM can bereplaced in the term of protein by10%ESBM without hampering cuttlefish perform.