Effects Of Dietary Protein And Zinc Level On Performance, Cytokines In Blood And Lymphoid Organ Of Early-weaned Piglets

The objective of this study was to evaluate the effects of different dietary CP and Zn level on development and immune function of lymphoid organs, and the persistence of microelement in lymphoid organs.32 crossbred piglets ([Yorkshire×Landrace]×Duroc),21 days of age, initial BW of 6.3±0.4kg) (CP (23%,17%) and Zn (100,3000 mg Zn/kg diet) from ZnO). The duration was 28 days. The results indicated that.1,The thymus index was increased in the high protein groups(P<0.05). The interacction by zinc level and protein level was significant(P<0.05), both in low level of zinc group and high level of zinc group, the thymus index was increased significantly(P<0.05). With zinc increased, the spleen indexes in the group with high protein were decreased by 9.8%, in the group with low protein decreased by 18.4%.2,Both level of protein diets added with high dosage of zinc had no effect on retention of the trace elements(Fe,Cu,Mn,Zn) in thymus and spleen, and high zinc level can significantly decreased Cu in thymus. With high level of protein, the Zn was dreased in liver(P<0.05). But the Zn in liver significantly was increased with high dose of ZnO(P<0.0001), and Fe was decreased in liver(P<0.0001).3,Diet with high level protein significantly increased the concentration of IL-1β(P<0.01) and IL-6 (P<0.05) in serum, while high level zinc can decrease them both (P<0.05) in day 0-14. Serum IL-1βand IL-6 concentration in the post-test(14-28d) were lower than the pre-test (P<0.05). In the same protein diets, the group with high level of zinc got lower serum IL-1βand IL-6 than the group with low level of zinc.The diets with high zinc increased serum IL-2 and INF-y(P<0.01 or P<0.05) in the whole test.4,With high dose of zinc, the IL-2 in thymus and spleen was increased (P=0.0013 or P=0.0083),and the INF-y in spleen was improved (P<0.0001), but the INF-y was decreased in thymus.In conclusion, high dosage of zinc supplementation can improve the performance of early-weaned piglets in day 0～21d, decrease the diarrhea, which is association with the decreasing of pro-inflammatory cytokines in serum and immune organs, especially in high protein diet (were more significant).