摘要This study was to evaluate the effects of the supplementation of saturated fatty acids with different chain lengths on growth performance,intestinal morphology,epithelial cell proliferation,differentiation and apoptosis in weaned piglets.Thirty-two weaned piglets(Duroc x Landrace x Yorkshire,BW=7.81±0.26 kg)were weaned at 21 d and randomly assigned to 1 of 4 experimental treatments:(1)a basal diet(control);(2)control+0.3％butyrate(BT);(3)control+0.3％lauric acid(LA);(4)control+0.3％stearic acid(SA).All piglets were then slaughtered for tissue sampling after having been fed experimental diets for 28 d after weaning.Supplementation of BT increased the gain-to-feed ratio(G:F)(P＜0.05)compared to piglets fed the control diet from 14 to 28 d.In addition,the villus height(VH)to crypt depth(CD)ratio(VH:CD ratio)of the ileum were higher in the BT and LA diets than that of the control diet(P＜0.05).The SA-supplemented diet increased ileal VH(P＜0.05),whereas the BT-supplemented diet increased jejunal CD(P＜0.05).Compared to the control,diets supplemented with BT,LA,or SA all tended to increase jejunal proliferation(Ki67/crypt positive cells)(P=0.190);diets supplemented with BTor SA significantly increased the number of ki67-positive cells in the ileal crypt(P＜0.05).Furthermore,in the jejunum,the protein expression of activated caspase 3 and villin were increased in piglets fed BT,LA,or SA diets compared to those on the control diet(P＜0.05).In the ileum,compared with the control diet,the BT diet tended to increase the protein level of mammalian phosphory-lation target of rapamycin(p-mTOR,P＜0.10);LA or SA diets significantly increased p-mTOR protein expression(P＜0.05).These results show that dietary supplementation of BT,LA,or SA promotes jejunal cell renewal in weaned piglets.At the same time,increased proliferation of ileal crypt cells by promoting p-mTOR expression has beneficial effects on ileal morphology in weaned piglets.