Effect Of Methionine On Growth Performance And Immune Function Of Piglets

This study examined the affect of different dietary methionine levels on growth performance and immune function of piglets. The test selected36piglets from the same source and with similar weight which were randomly divided into six groups, each group has three repeats, and each repeat has2piglets. Six group were fed the diet with methionine level of0.18%,0.24%,0.30%,0.36%,0.42%and0.48%.The test has7days pre-feeding period, and then28days feeding period. The results are as follows:Test one, the result of different methionine levels on the growth performance of piglet was significant (P<0.05). The average daily feed intake in0.24%methionine group was significantly higher than0.42%and0.48%methionine treated group (P<0.01), and then significantly higher than the0.36%methionine treated group (P<0.05);0.30%treated group was significantly higher than the0.48%methionine treated group (P<0.05), and other groups has no significant difference (P>0.05). The final weight in0.24%and0.30%methionine treated group was significantly higher than the other four treated groups (P<0.01), but the two groups has no significant difference (P>0.05);0.36%and0.42%methionine treated group was significantly higher than0.18%and0.48%methionine treated group (P<0.01). The average daily gain in0.30%methionine group was significantly higher than0.42%and0.48%methionine treated group (P<0.01), and also significantly higher than0.18%and0.36%methionine group (P<0.05);0.24%methionine treated group was significantly higher than0.42%and0.48%methionine group (P<0.01), the other groups has no significant difference (P>0.05). In summary, the appropriate methionine level for piglets to keep a better growth performance is0.30%.Test two, the different levels of methionine have significant affect in peripheral blood of CD4+/CD8+as well as serum concentrations of cytokines (P<0.05). CD4+/CD8+in0.30%methionine treatment groups achieved maximum in the latter two periods which was significantly higher than the other five groups (P<0.05), CD4+/CD8+in0.18%methionine treated group was significantly lower than the other five methionine group (P<0.05). The peripheral blood serum concentrations of three cytokines in the beginning of the experiment has no significant difference (P>0.05). In the last period, the peripheral blood serum concentration of IL-2in0.30%methionine treated group reached the highest level of547.10ng/L, significantly higher than the other five methionine treated groups (P<0.05), the concentration of IL-2in0.24%and0.36%methionine treated group were significantly higher than0.18%,0.42%and0.48%groups (P<0.05). In the last period of the test, the peripheral blood serum concentration of γ-IFN in0.30%and0.36%methionine treated group was significantly higher than the other four methionine treatment groups (P<0.05), and the concentration of y-IFN in 0.30%methionine treated group reached386.01ng/L; the concentration of γ-IFN in0.18%methionine treated group was significantly lower than the other five groups (P<0.05). Throughout the test period, the concentration of TNF-α in the six methionine treatment groups has no significant difference (P>0.05). In summary, under the cellular level, the appropriate methionine level for piglets to maintain a strong immune function is0.30%.Test three, the affect of piglet spleen index and thymus index with different levels of methionine on piglets was significantly (P<0.05), there was no significant effects on liver index (P>0.05). The spleen index in0.18%,0.24%,0.30%and0.36%groups was significantly higher than0.42%and0.48%methionine groups (P<0.01). The thymus index in0.24%,0.30%and0.36%groups was significantly higher than0.42%and0.48%groups (P<0.05). The liver index in the six methionine treated groups has no significant difference (P>0.05). The expression of IL-2mRNA in0.30%methionine treated group was significantly higher than0.18%,0.24%and0.36%groups (P<0.01); The expression of IL-2mRNA in0.42%and0.48%groups was significant lower than0.24%methionine treated group (P<0.01). Therefore, when the methionine level of dietary is0.30%, the piglets had a higher expression of IL-2mRNA in spleen.In summary, under the conditions of this experiment, in order to achieve a better growth performance and immune function for piglet, the appropriate methionine level is0.30%.