日粮中性洗涤纤维(NDF)添加水平对生长肉兔肠道PP结内M细胞数量及形态特征的影响

Effects of dietary NDF levels on number and morphological characteristics of M cell in intestinal Peyer’s patches of growing meat rabbits

旨在研究饲粮中不同中性洗涤纤维(NDF)水平对生长肉兔肠道派尔氏(PP)结内微皱褶(M)分化细胞数量及形态特征的影响。选用150只体质量相近健康断奶仔兔(35日龄),随机分成3组,每组50个重复,每个重复1只试兔,分别饲喂31.32%(LF组)、37.36%(对照组)、41.84%(HF组)3种不同NDF水平试验饲粮。预试期7 d,正试期23 d。Western blot试验表明,鼠抗人波形蛋白抗体适用于兔M细胞示踪。在光学显微镜下观察,饲喂30 d后各组试兔肠道PP结淋巴滤泡圆顶区上皮顶端聚集大量成熟M细胞,形成典型口袋状结构,而饲喂试验日粮前试兔肠道PP结内多为未成熟的M细胞,位于圆顶区两侧,呈柱状。试验日粮饲喂前(35日龄)各组间试兔肠道PP结内M细胞数量及M细胞分化相关基因RNAK/RANKL/OPG表达水平无显著性差异。试验日粮饲喂后(65日龄),HF组试兔肠道PP结内M细胞数量显著高于对照组和LF组(P<0.019);HF组试兔肠道PP结内促进M细胞分化的RANK基因表达水平显著高于LF组;同时与LF组相比,HF组试兔肠道PP结内抑制M细胞分化的OPG基因表达量显著降低(P<0.001)。结合本试验及前期试验结果,仔兔可在断奶后15~20 d内添加日粮NDF水平为37.36%~41.84%,生长后期可适当降低纤维水平,短时间内饲喂高纤维日粮以激发M细胞的数量及成熟,以尽早建立有效的肠道黏膜免疫保护,而后要适当降低饲喂纤维水平,以保持良好的生长性能。

To investigate the effects of different neutral dietary fiber(NDF)levels on the number and morphological characteristics of M cells in intestinal Peyer’s patches(PP)of growth meat rabbits.One hundred and fifty 35-day-old weaned meat rabbits with similar relative body quality weight were randomly divided into 3 groups with 50 replicates in each group and each replicate contained 1 rabbit,which respectively fed three different experimental diet that NDF levels were 31.32%(LF group),37.36%(control group),41.84%(HF group).The test period included 7 d for adaptation and 23 d for trial period.Western blot result showed that the mouse anti-human vimentin antibody was suitable for tracing rabbit M cells.Under the light microscope,the higher amount of mature M cells were aggregated at the top of the epithelial area in all the PP lymphoid follicle dome after feeding for 30 d,and the typical pocket like structure was formed.Before feeding experimental diets,the rabbit PP contained columnar immature M cells,located on both sides of the dome.Comparing before and after feeding,the number and morphology of M cells were statistically analyzed in each treatment group.The results showed that there was no significant difference in the number and the differentiation-related genes of M cells among the groups at 35 days old.However,after the test diet,the large number of M cells in the intestinal PP from HF group was significantly higher than that of control group and LF group(P<0.019)at 65 days old.The RANK gene that promoted M cell differentiation was significantly higher in the HF group than in the LF group,and the OPG gene expression that inhibited M cell differentiation was significantly lower than that in the LF group(P<0.001).In combination with the results of the present and the previous study,the rabbit can add 37.36%-41.84%NDF levels within 15-20 dafter weaning,and properly reduce NDF levels in the growth stage.Feeding high-fiber diet in a short period can stimulate the number and maturity of M cells in order to establish effective mucosal immune protection as early as possible.Then the dietary fiber level appropriately reduce so as to keep good growth and development.