Effect And Mechanism Of Several Non-nutritional And Non-pollution Additives On Turbot (Scophthalmus Maximus L.)

In order to study the effects of three new additives on growthperformance, water quality factors, non-specific immune factors, digestive enzymes,protein digestion and fecal protein excretion of turbot(Scophthalmus maximus L.),5 trial diets were applied for five treatments and 11 fish were kept in each of thetriplicate tanks designed for every treatment group. None of the three additivessupplement was added in basal diet(BASAL)which was applied as control group. 0.04%of xylo-Oligosaccharides(XOS), 0.13% of yeast cell wall(YCW), 0.07% of bileacid(BILE)and mixture of the three(MIX)were added in basal diet, respectively,formed other 4 trial groups. We reared the turbot about 72d (average initial weight151.3±15.2 g) in the form of random design. The results were as follows:MIX had the best effect on growth performance and feed utilization, YCW or XOSwas better and BILE was good. Comparing with BASAL, the WGR in 4 groups(MIX,YCW,XOSand BILE) enhanced by 15.4%,13.9%,12.4%(p<0.05)and 7.4%(P>0.05), respectively;feed modulus decreased by 6.9%,6.2%和 5.4%(p<0.05)and 3.8%(P>0.05) , respectively.Water quality factors were affected no significantly by different additives(P>0.05) ,which instructed that the additives could keep the water qualitystabilization. Comparing with BASAL, ammonia in water of the 4 groups enhanced by4.0%,3.2%,3.0%和 0.8% (P>0.05), respectively;COD enhanced by 2.8%,-2.2%,-3.4%and 0.8% (P>0.05), respectively. According as the result above, we advised seawaterenvironmental factors(NH4-N,PO4-P,COD) should be one of the main reference indexon nutrition and feed research of aquatic animals.MIX had the best effect on complement C3 and C4 activity, SOD activity,phagocytic activity. YCW had better effect on complement C3 activity and phagocyticactivity while XOS had better effect on complement C4 activity and phagocyticactivity. BILE had little effect on non-specific immune factors.Comparing with BASAL, the protease activity of stomach and foregut in the 4groups enhanced by 20% and 24%,17% and 19%,16% and 15% (p<0.05) and 11% and 3%(P>0.05),respectively;the lipase activity in foregut and hindgut by 22% and 19%, 19% and17% (p<0.05),7% and 12%(P>0.05) and 19% and 18%(p<0.05), respectively.Protein digestibility of the 4 groups enhanced by3.6%,2.9%,3.7%(p<0.05)and 1.5%(P>0.05),respectively;fecal protein excretion decreased by 12.7%,7.1%,13.4%和 2.4%(p>0.05), respectively. That showed water pollution decreased fromfecal protein excretion in 4 trial groups.Therefore, comprehensively analyzing the digestive enzymes, the blood immunefactors, the growth performance,feed utilization, protein digestion of juvenileturbot and seawater environmental factors, we concluded that the mixture of 3additives achieves the best effect, adding yeast cell wall or XOS single was betterand adding bile acid single was good on turbot.