Effect Of Dietary Oxidiezd Fish Oil And MDA On The Growth Performance And Health Of Grass Crap (Ctenopharyngodon Idellus)

Two 72-day experiments are carried out to investigate the effect of dietary oxidised fish oil and MDA on growth performance, structure and function of hepatopancreas and structural integrity and function of the intestinal mucosa membrane of grass carp (Ctenopharyngodon idellus).Test 1:Five diets containing difference levels of soybean oil, fish oil and oxidized fish oil (6% fish oil,6% soybean oil,2% oxidized fish oil; 4% oxidized fish oil,6% oxidized fish oil) are evaluated at Nitrogen and so on energy. Results show that:(1) Compared with 6% soybean oil, the SGR of grass carp feed with 6% fish oil,2% oxidized fish oil,4% oxidized fish oil, and 6% oxidized fish oil decreases 5.81%～11.50%, FCR increases 8.64%-17.28%; (2) LRR significantly increases (p<0.05), PRR significantly decreases (p<0.05); (3) The require of n-3 and n-6 Fatty acids is increased; (4) Oxidized fish oil can significantly increase (P<0.05) the content of ALB, GLB, MDA, GSH of grass carp serum and significantly reduce (P<0.05) the content of GSH, SOD of grass carp hepatopancreas; (5) Oxidized fish oil will significantly decrease (P<0.05) the HSI, the lipid content of hepatopancreas and the TG content of serum, significantly reduce (P<0.05) the ratio of HDL and LDL at the same time; (6) The content of TC of serum and hepatopancreas and the content of TBA of hepatopancreas significantly increase (P<0.05), while the content of TBA of serum is significantly reduced (P<0.05) by the oxidized fish oil; (7) Oxidized fish oil will cause grass carp fatty liver, damage the mitochondrial of hepatopancreas and cause hepatopancreas cell fibrosis and tissue atrophy; (8) Compared with the 6% soybean oil, the oxidative product of fish oil can increase the MDA and GSH content of serum and intestine. But as the content of oxidized fish oil rising GSH content falling; (9) The bile acid content of intestine is significantly reduced (P<0.05) by the oxidized fish oil; (10) The number of goblet cell significantly enlarge (P<0.05) with the increasing content of oxidized fish oil; (11) The microvilli of intestine is hyperplasia firstly, then atrophied in the 6% oxidized fish oil group. In conclusion, (1) Oxidized fish oil may reduce the PRR by reducing the growth rate and feed efficiency of grass carp; (2) Oxidized fish oil will change the muscle fatty acid composition of grass carp, and increase the n-3 and n-6 content of fatty acid; (3) Oxidized fish oil may interfere with the metabolism of fat in hepatopancreas, cause hepatopancreas steatohepatitis and fibrosis, and also damage the mitochondria; (4) Oxidized fish oil can increase permeability by damaging the intestinal tight junctions, and endotoxin content in serum will significantly increase; (5) Oxidized fish oil will interfere with bile acid cycle by the deposition of bile acids in hepatopancreas.Test 2:Two diets containing fresh soybean oil, low oxidized fish oil and three with different levels of MDA (S, Ml, M2, M3, F) are evaluated at Nitrogen and so on energy. The results show that:(1) FCR, SGR and PRR will significantly reduce (P<0.05) by MDA and other oxidation products, and only MDA can significantly reduce (P<0.05> the LRR; (2) CF will significantly reduce (P<0.05) by MDA, and HSI will reach the highest in M1 then reduce; (3) MDA and other oxidation products will significantly increase (P<0.05) the fat content in hepatopancreas; (4) MDA and other oxidation products will significantly reduce (P<0.05) TBA content in serum, and significantly increase (P<0.05) the activity of SOD and TC, TG and MDA content in serum, significantly reduce (P<0.05) the ratio between HDL and LDL, and the ratio between’ ALB and GLB; (5) MDA and other oxidation products will significantly increase (P<0.05) TC content of hepatopancreas, and significantly reduce (P<0.05) SOD activity, and the high content of MDA in diet will significantly increase (P<0.05) MDA content in hepatopancreas; (6) MDA will cause grass carp fatty liver, damage the mitochondrial of hepatopancreas and cause hepatopancreas cell fibrosis and tissue atrophy, and other oxidation products just change the shape of mitochondrial; (7) The bile acid content of intestine was significantly reduced (P<0.05) by MDA; (8) The number of goblet cell and was significantly enlarged (P<0.05) with the increasing content of MDA and other oxidation products; (9) The microvilli of intestine was hyperplasia firstly by MDA and other oxidation products, then atrophied in the M3 group; (10) MDA can increased permeability by damaging the intestinal tight junctions, and endotoxin content in serum will significantly increase. In conclusion, (1) MDA can cause oxidation stress, and interfere with digestion and absorption of fat, then lead to the growth performance degradation and atrophy of hepatopancreas, increase the probability of occurrence of steatohepatitis; (2) MDA will cause hepatopancreas oxidative stress and damage the function of mitochondria, then reduce antioxidant capacity of hepatopancreas, lead to increase risk of hepatopancreas fibrosis; (3) MDA may be a major factor in the decreasing of LRR; (4) Effect by the antioxidant enzymes, other oxidation products can not increase MDA content in hepatopancreas, but MDA can; (5) MDA focuses on changing the internal structure of mitochondria, and other oxidation products are mainly affects the shape of mitochondria; (6) MDA and other oxidation products both can damage the intestinal tight junction structure and increase intestinal permeability; (7) MDA will reduce the TBA content in serum which is reabsorbed from intestine, thus affecting the normal circulation of TBA of grass carp.