Effects Of Crude Porphyra Polysaccharide On Growth Performance,Biochemical And Immunological Parameters Of Epinephelus Coioides

This experiment was conducted to investigate the effects of crude polysaccharide fromPorphyra in the diet on growth performance, biochemical and immunological parameters of Epinephelus coioides.Meanwhile, the findings will provide useful information on alternative feed additive to antibiotics and other undesirable additives to improve fish production without harmful effects on the environment or inducing antibiotic resistance.One hundred and twenty groupers with the similar length and weight were randomly divided into four groups. Blank control group was fed with the basal diet, while A, B, C groups were fed with the basal diet supplemented with 0.5,1.0, and 1.5 (%) Crude Porphyra Polysaccharide (CPP) for 48 days. Body weight and length were measured to investigate fish growth performance. The blood was collected to investigate the biochemical parameters (TP、UREA、CREA、ALKP、AST, ALT),antioxidant-related parameters (SOD、CAT、 LZM), complement activity (C3、C4)and inflammatory cytokines(IL-2、IL-6、IFN-a).And the gut was used to measure the digestive enzyme activities (pepsin,intestine proteinase,disaccharidase), observed the intestinal tissue morphology, and to count the immune cell numbers.Results:(1)WGR, SGR:Group A>Group B>Group C> Control group. FC:Control group> Group C> Group A> Group B.CF:Group B> Group A> Group C> Control group. Dietary supplementation of CPP regardless of inclusion level could increase WGR,SGR, CF,and decrease FC. WGR in group A and group B were significantly higher than that in the control group(P< 0.05). Viscerosomtic index and hepatosomatic index have no significant differences among the groups(P >0.05). This revealed that CPP could promote the growth of thefish and CPP has little effect on the liver and kidney of fish.(2)The results showed that CPP in the diet could significantly increase the level of TP, among these, group A has the highest level of TP (P<0.01). But the level of UREA and CREA were lower in the CPP treatment groups than that in the control group. There were no significant differences in the levels of alkaline phosphatase (ALKP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in control and treated groups (P>0.05), suggesting that the CPP had no adverse effect on liver or kidney function ofEpinephelus coioides.(3)With the doses of CPP was increased, SOD and CAT activities were also increased. The highest SOD, CAT activities was group C. There were no significant differences in the levels of LZM in control and treated groups(P>0.05). The treated groups’ levels of LZM were higher than the control group; and group A has the highest level of LZM. C3 decreased significantly in treated groups than that in control group (P<0.05).C4 activitiesin treated groups showed a "folded" situation, the difference is not significant(P>0.05).This indicated that the appropriate dose ofCPP in grouper diet had a promoting effect on SOD, CAT, C3 activities. CPP had little effect on LZM, C4, and high concentration of CPP could inhibited the activity of LZM, and C4.(4) IL-6 and IFN-a increased significantly in treated groups than that in the control group (P <0.01); IL-2 increased significantly in group B than that in the control group (P<0.01). In general, compared with the control group, the IL-2, IL-6, IFN-a in group B increased obviously. This showed that CPP can significantly increase the level of IL-6, IFN-a, IL-2.And ithave an immunomodulatory activity in Epinephelus coioides.(5)The activities of pepsin and intestine proteinasefirstly increased and then decreased with the doses of CPP. CPP significantly improved the activities ofmaltase and invertase than the control group (P<0.05).The lactase activities in treated groups were higher than the control group, but no significant different was observed(P>0.05). Therefore, CPP can enhance the activities of pepsin,intestine proteinase,maltase,invertase. But CPPhad little influence on activity of lactase and high doses of CPP could inhibit activities of pepsin andintestine proteinase.(6)The villi length in the treated groups was higher than that in the control group, but the width of the villi have no differences between control and treated groups (P>0.05). In the treated groups, muscle thickness of groupers’foregut and hindgut increased with the increase doses of CPP. The muscle thickness of hindgut firstly increased and then decreased with the doses of CPP increased. It had the same tendency in intestinal intraepithelial lymphocytes (IEL) with the muscle thickness. In the foregut, IEL increased 66.66% in group A (P<0.01). Mucous cells in the digestive guts showed a gradual decreasing trend in general, the mucous cells in the foregut were highest. Mucousin group B, group C increased by 64%,41.7%(P<0.01). This indicated that CPP have stimulated effects on length of villi, thickness of the muscle, IEL, mucous cells of groupers and the CPP exhibited high concentrations inhibition, but CPP have less effects on the villus width of groupers.Conclusion:the addition of appropriateCPP in the basic diet could improve the growth performance, biochemical parameters and immunological of orange-spotted grouper.lt was proved that appropriate amount of CPP had a promoting effect. On the contrary, it had immunosuppressive effect at the high doses. And the dosage was better in the range of 0.5% to 1.0%.