A Study Of Ratio Of Poly Unsaterated Fatty Acid On The Immune Stress In Rong Chang Weaning Piglets

The stress after piglets weaning is a severe problem disturbing the swine production. This experiment was aimed to find a appropriate ratio of n6 to n3 poly unsaturated fatty acid (PUFA) and which would be hoped it would be helpful to make a better utilization of the lipid in the weaned piglets diet. The experiment was conducted to research the effect on the growth performance, blood chemical parameter, instinal morphology and instinal mucosa parameter of two different fatty acid ratio under the immune stress in weanling piglets through adding different fatty acid to control the n6 to n3 PUFA ratio.Twenty four healthy Rong Chang weanling piglets with weight of 6.80±0.55 kg was randomly divided into four groups(n=6), which was designed by the 2X2 factorial, and the two factors were two different injections of physiological saline and lipopolysaccharide (LPS), the two levels were n6:n3=10:land n6:n3=20:1 ratios of PUFA. The pretesting span was three days and the testing term twenty-one days. The four groups were respectively injected physiological saline and LPS according to corresponding treatments.Results indicated as follow:(1) Growth performance:the two different ratios of n6 to n3 PUFA did not significantly affect the average daily gowth and average daily intake (p>0.05), however, the group of n6:n3=10:1 was higher than that of n6:n3=20:1 (p>0.05) particularly, the difference was significant in the first week after weaning (p<0.05) The diarrhea rate of group n6:n3=10:1 was lower that of n6:n3=20:1 (p<0.05) especially, the difference was extremely different in the third week (p<0.01)(2) Blood chemical parameter:the content of IL-1 in plasma of n6:n3=20:1 group under the stimualation of LPS increased significantly (p<0.05) and that of n6:n3=10:1 group was not affected (p>0.05). The concentration of IL-6 and TNF-αin plasma of the two different fatty acid ratio groups increased significantly under the stimualation of LPS (p<0.05). The content of PGE2 of n6:n3=20:1 group increaesed significantly(p<0.05)while n6:n3=10:1 group had no difference (p>0.05)(3) Instinal morphology:the effect on jejunal and ileal villus height, crypt depth and ileal ratio of villus height to crypt depth in weaning piglets of the two different fatty acid ratio treatments was not different (p>0.05). After the stimulation of LPS, the jejunal and ileal villus height, the ratio of jejunal and ileal villus height to crypt depth was decreased (p<0.05), however, the jejunal and ileal crypt depth was increased (p<0.05)(4) Instinal mucosa parameter:the jejunal and ileal concentration of secretive IgA treated by the both PUFA ratio groups increased by the stimulation of LPS (p<0.05),but the ileal content of VIP was not affected (p>0.05).The jejunal content of Substance P and VIP and the ileal concentration of Substance P treated by the ratio of n6:n3=20:1 PUFA group increased, but the difference was not significant (p>0.05), in contrast, which decreased differently (p<0.05) when they were treated by the ratio n6:n3=10:1 PUFA group.