Dietary butyrate, lauric acid and stearic acid improve gut morphology and epithelial cell turnover in weaned piglets.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 × Landrace × 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).  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 BT or 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 phosphorylation 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.
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