Study On Feeding Strategies Of Oplegnathus Fasciatus

Oplegnathus fascltus is highest nutritional and most economic in the fish farming.Under the angle of morphological characteristics, physiology and ecology, artificialreproduction and production management, thremmatology and so on， scholars haverecently done a lot of research to Oplegnathus fascltus which has been farming in mostarea of our country. The purpose of feeding strategy includes the selection of optimalfeeding frequency, selecting the optimal feeding rate and finding best compensatorygrowth. The growth of juvenile Oplegnathus fascltus and biological enzyme activitywas studied and analysis under the angle of feeding strategy to mainly investigate theoptimum feeding frequency, the optimum feeding rate, the best compensation growthand the response mechanism of biological enzyme in the starvation. This study aims toimprove economic efficiency, with building reasonable feed regime to improve feedingconversion rate and to reduce production cost. Beside to provide reference materials forlarge size Oplegnathus fascltus industrialized farming.1. The aims of this study was to investigate the effect of feeding frequency on tissuemetabolic enzyme activities and glycogen contents of Oplegnathus fasciatus with anaverage weight of10.0±1.0g. Five experimental groups were designed, fiveexperimental groups （0.5,1,2,3,4times per day） were designed for a30-day trial. Theresults showed that, with the feeding frequency increase, the SGR had an increasingtendency. However, there were no significant increase in SGR and digestive enzymeactivity at higher feeding frequency （more than2times/d）. Accossing to the angle ofdigestive enzyme, the optimum feeding frequency was2times per day for the juvenileOplegnathus fasciatus.2. The aim of this study was to investigate under the confident of different feedingrate the effects on body weight, the rate of add weight per day, feed coefficient ofOplegnathus fasciatus with an average weight of30.0±1.0g. Five experimental groupswere designed, the feed rate is the percent of body weight of Oplegnathus fasciatus. fiveexperimental groups （A（Daily food consumption3%）, B（Daily food consumption5%）,C（Daily food consumption7%）, D（Daily food consumption9%）, E（Daily food consumption11%）and two times per day） were designed for a30-day trial. The sampleswere collected at the initial experiment, and body weight, the rate of add weight per day,feed coefficient were analyzed. The results showed that, the juvenile Oplegnathusfasciatus is increased as a result of different feed rate. the previous period appeareddifferent significantly.But have no significantly different after the group of7%.the effectof feed coefficient appeard increasing tendency. the previous period is steady andinsignificantly, but after the group of7%have significantly difference. The effect onbody composition had a little significantly difference in Protein and Lipid, but notobviously, The rest group of date had insignificantly difference. In conclusion, in thegroup of7%, the rate of add weight per day is higher and the feed coefficient is lower.In the condition of this experiment, the optimum feeding rate is7%for the juvenileOplegnathus fasciatus with an average weight of30.0±1.0g in the course of extensiveproduction.3. This study was to investigate the effects on growth status, physiologic andbiochemical index in the condition of starvation and reefeeding with an average weightof10.0±1.0g.This experiment was divide into two part. The first part was toinvestigate the effects in the condition of starvation and refeeding on growth anddigestive enzyme activity of Oplegnathus fasciatus and the second part was toinvestigate the effects on tissue metabolic enzyme activities and glycogen contents in it.In the first experiment of starvation and refeeding, the results showed that, the bodyweight, proteinase （pepsin and trypsin） and lipase activities decreased obviously withthe starvation time increasing. Significant differences in body weight and pepsin activitywere observed between control group and the group after starving for6days. Lipaseactivity after starving for9days was significantly lower than that of the control group.The amylase activity during the whole experiment period fluctuated. After refeeding,the fish body weights and SGRs of groups （except S3） were significantly lowered thanthose of control group. However, no significant differences in body weight and SGRwere found between the groups of S3and the control. The proteinase and lipaseactivities after recovery feeding had been obviously increased. There was noinsignificant difference in proteinase activity between the starvation groups and thecontrol. However, the lipase activity after relatively long starvation （9～12days） did notreturn to the level of the control group. In conclusion, based on the results of our study,it was indicated that juvenile Oplegnathus fasciatus of3-day deprived group had fully compensatory growth ability.The results on tissue metabolic enzyme activities andglycogen contents showed that, serum and liver glycogen contents were significantlyaffected by the starvation and refeeding, and serum glycogen （except S12group） andliver glycogen contents were reduced significantly as a result of starvation, while theliver glycogen contents returned to the level of control group after refeeding. However,only a little affection on the muscle glycogen contents was found during the starvationand refeeding. During the period of experiment, the AKP and GPT activities of serumand liver were significantly affected by starvation, and after refeeding, the both enzymesactivities returned to the levels of control group. However, during the wholeexperimental period, the effects of starvation and refeeding on muscle AKP, ACP, GPTand GOT activities were very little. In conclusion, the serum glycogen content with alevel of2.65±0.33～3.70±0.36(mmol L^-1)was essential to maintain the stabilization ofbody metabolism. The main metabolic enzymes in serum and liver were very importantin maintaining the basic metabolism of Oplegnathus fasciatus under the condition ofstarvation.