| The effects of tremella polysaccharides as a feed additive replacing quinocetone plus high level of copper (Cu) on the growth performance and immune function of weanling pigs were investigated, and also the potential mechanism of these effects were discussed. Twenty-four weanling PIC pigs with age of 28±2d and initial body weight (BW) 6.99±0.45kg were randomly assigned to four treatments according to gender and BW by single factor design. Each treatment had 6 replicates and 1 piglet in each replicate. The four treatments were the control group with basal diet and the other three groups with 0.4% tremella polysaccharides (TPs), quinocetone plus high Cu group (Q＋Cu) and 0.4% tremella polysaccharides plus high Cu (TPs＋Cu) supplemented respectively. The basal diet was based on corn-soybean formula according to the NRC (1998) nutrient requirement for 5-10kg lean piglets. During the four weeks' experiment the piglets were allowed ad libitum to feed and water. Feed consumption, average daily gain (ADG), feed to gain ratio (F/G) and diarrhea frequency were investigated. At the end of the experiment the blood samples were collected, and the percentages of CD3~+, CD4~+ and CD8~+ T-lymph cells were assayed by three-color fluorescent flow cytometry technique, and accordingly the CD4~+/CD8~+was calculated. In the peripheral blood serum, the levels of IgG, IgM and IgA were determined using immunoprecipitin method, and IGF-1 was determined by ELISA technique. The results were as follows:1. The piglets in TPs, Q＋Cu and TPs＋Cu groups had a better growth performance than those in the control group (P＜0.05), but among the former three groups there were no difference in performance improvement (P＞0.05). The ADG of piglets in the control, TPs, Q＋Cu and TPs＋Cu groups were 338.6g/d, 412.9g/d, 404.2 g/d and 412.9g/d respectively, and the corresponding F/G were 1.85, 1.61, 1.64 and 1.62.2. Compared with that in the control group, the diarrhea frequency in the TPs, Q＋Cu and TPs＋Cu groups were significantly decreased by 21.43%, 20.84% and 22.62% respecitively.3. Both the serum IgG and IgM levels in the TPs group were higher than those in the Q＋Cu group (P＜0.05), And in the TPs＋Cu group, the levels of IgM and IgA were higher than those in the Q＋Cu group (P＜0.05), While in the rest two-group comparisons, no significant differences (P＞0.05) in serum IgG, IgM and IgA levels were observed. As to the subgroups of blood lymph cells, the CD8~+ percentage in the TPs group was lower than that in the Q＋Cu group with great significance (p＜0.01), and also the CD4＋/CD8＋in the TPs group was significantly higher than that in the later group (p＜0.05). For the rest two-group comparisions, the differences were not significant.4. The serum IGF-1 level in the TPs group was significantly higher (P＜0.01) than both in the Q＋Cu and the control group. No significant differences exsisted among the rest groups.In conclusion, the 0.4% tremella polysaccharides was equal with the quinocetone plus high Cu in promoting growth performance. The supplement of high Cu in addition to tremella polysaccharides did not change the performance and immune function, which indicated that there was no additive effecet between the two factors. Compared with quinocetone plus high Cu,, the supplement of tremella polysaccharides was more proned to enhance the cellular and humoral immune functions. In weanling piglets, the favorable effect of tremella polysaccharides on the growth performance may closely related to its contribution to improve the cellular immune status and the secretion of growth hormone, IGF-1. |
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