Dissertation
Dissertation > Agricultural Sciences > Aquaculture, fisheries > Aquaculture technology > A variety of fish farming > Marine fish > Other

Effects of Dietary Small Peptides Levels on Growth Performance, Muscle Quality, Physiological and Biochemical Indexes in Juvenile Starry Flounder (Platichthys stellatus)

Author JiangKeJun
Tutor WangJiYing
School Shanghai Ocean University,
Course Animal Nutrition and Feed Science
Keywords Starry flounder(Platichthys stellatus) small peptides growthperformance digestive enzymes activities muscle quality serumparameters
CLC S965.399
Type Master's thesis
Year 2013
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Exp.1Effects of dietary small peptides levels on grwoth performance andthe digestive enzymes activities of juvenile Platichthys stellatus.The purpose of this experiment was to study the effect of different levels ofsmall peptides on growth performance and the digestive enzymes activities of juvenilestarry flounder(Platichthys stellatus).540fish with an average body weight of(15.30±0.03)g were randomly divided into6groups equally with3replicates, whichwere fed experimental diets supplemented with0(control group),0.25%,0.50%,0.75%,1.00%,1.50%small peptides respectively. After an8-week trial, the resultsshowed as follows:1) the weight gain rate (WGR), voluntary feed intake(VFI), feedintake rate (FIR), specific growth rate (SGR) and protein efficiency ratio (PER) in0.75%and1.00%groups were higher than control group, significantly (P<0.05);Compared with other groups, the feed conversion ratio (FCR) in control group wassignificantly higher (P<0.05). No significant difference was found in HSI, VSI, CFand SR among all groups.2) In all groups, the protease and amylase activities of thestomach and intestine showed an increasing-decreasing trend with increasing dietarysmall peptides levels. Both of the activities peaked at1.00%group, which weresignificantly higher than0.25%and1.50%groups (P<0.05). The protease activity ofliver in0.50%~1.00%groups were different with control group, it was significantlyhigher(P<0.05), and no significant difference was found in the amylase activity ofliver (P>0.05). The results indicate that small peptides can effectively improvegrowth performance and the digestive enzymes activities of juvenile starry flounder,and the optimum dietary small peptides level is1.00%under this experimentalcondition.Exp.2Effects of dietary small peptides levels on muscle quality and serum parameters of juvenile Platichthys stellatus.This study was to determine the effect of dietary small peptides levels on musclequality and serum parameters of juvenile starry flounder. Six isonitrogenous diets with0%,0.25%,0.50%,0.75%,1.00%and1.50%small peptides supplementation werefed to triplicate groups of fish, respectively. The result showed that:1) In dorsalmuscle, the crude lipid content decreased initially and then increased with increasingsmall peptides levels, and that of all supplementation groups except0.25%group wassignificantly lower than that of control group (P<0.05); the crude protein content in1.00%and1.50%groups was significantly higher than that in control group (P<0.05);No significant difference was found in the content of moisture and ash among allgroups (P>0.05).2) Amino acids contents of all supplementation groups were higherthan that of control group except valine (VAL) and tyrosine (TYR) contents, nosignificant difference was found (P>0.05).3) The higher SFA content and lowerMUFA content were found in control group (P>0.05). PUFA content in0.75%and1.00%groups was significantly higher than that in control group (P<0.05). AmongPUFAs, both DHA and EPA levels in0.50%,0.75%and1.00%groups increasedsignificantly compared with control group (P<0.05). No significant difference wasobserved on ARA level (P>0.05).4) Compared with the control group, serum totalcholesterol (TCHO) content in0.50%group was significantly decreased (P<0.05);Secrum triacyglycerol (TG) content in all supplementation groups significantlydecreased (P<0.05); serum total protein (TP) and globulin (GLB) contents weresignificantly increased (P<0.05), and no significant difference was observed inalbumin (ALB) content (P>0.05). Therefore we can draw that small peptides caneffectively improve muscle quality and serum parameters, and the optimum dietarysmall peptides level is1.00%.Exp.3Effects of dietary small peptides levels on immunological andantioxidant parameters of juvenile Platichthys stellatus.The objective of this experiment was to investigate small peptides on the juvenilestarry flounder immunological and antioxidant parameters of with initial weight(15.30±0.03)g. The basal diet was supplemented with0%,0.25%,0.50%,0.75%,1.00%and1.50%small peptides, respectively. And the experiment lasted for8weeks.The results showed that1) Serum lysozyme (LSZ) activity was significantly higherthan the control, and the highest was found in1.00%group (P<0.05). Serumcomplement3content was significantly improved by dietary small peptides supplementation (P<0.05), and the highest level appeared in fish fed1.00%smallpeptides.2) Serum total antioxidant capacity (T-AOC) and glutathione peroxidase(GSH-PX) activity in1.00%and1.50%groups were higher than control group,significantly (P<0.05). Serum glutathione reductase (GR) activity in0.75%and1.00%groups was significantly higher than that in other groups (P<0.05). Comparedwith the control group, serum catalase (CAT) activity significantly increased (P<0.05),whereas serum maleic dialdehyde (MDA) content significantly decreased (P<0.05).Serum superoxide dismutase (SOD) activity increased with increasing dietary smallpeptides levels, but no significant difference was observed compared with controlgroup (P>0.05).3) No significant difference was found on liver soperoxide dismutase(SOD) and glutathione reductase(GR) activities among all groups (P>0.05). Livermaleic dialdehyde (MDA) content of all supplementation groups was significantlylower than that of control group (P<0.05) except0.25%group. Liver glutathioneperoxidase (GSH-PX) activity was increased initially and decreased subsequentlywith increasing dietary small peptides levles, and that in0.25%~1.00%groups wassignificantly higher (P<0.05). The results suggest that small peptides are able toeffectively improve the immunological and antioxidant parameters of fish, and theoptimum dietary small peptides level is1.00%.

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