Summary MicroRNA (miRNA)‐mediated regulation of auxin signaling components plays a critical role in plant development. miRNA expression and functional diversity contribute to the complexity of regulatory networks of miRNA/target modules. This study functionally characterizes two members of the rice (Oryza sativa) miR393 family and their target genes, OsTIR1 and OsAFB2 (AUXIN SIGNALING F‐BOX), the two closest homologs of Arabidopsis TRANSPORT INHIBITOR RESPONSE 1 (TIR1). We found that the miR393 family members possess distinctive expression patterns, with miR393a expressed mainly in the crown and lateral root primordia, as well as the coleoptile tip, and miR393b expressed in the shoot apical meristem. Transgenic plants overexpressing miR393a/b displayed a severe phenotype with hallmarks of altered auxin signaling, mainly including enlarged flag leaf inclination and altered primary and crown root growth. Furthermore, OsAFB2‐ and OsTIR1‐suppressed lines exhibited increased inclination of flag leaves at the booting stage, resembling miR393‐overexpressing plants. Moreover, yeast two‐hybrid and bimolecular fluorescence complementation assays showed that OsTIR1 and OsAFB2 interact with OsIAA1. Expression diversification of miRNA393 implies the potential role of miRNA regulation during species evolution. The conserved mechanisms of the miR393/target module indicate the fundamental importance of the miR393‐mediated regulation of auxin signal transduction in rice.

A total of 144 weaned piglets were used to evaluate the effects of essential oil (EO) supplementation of a low-energy diet on performance, apparent nutrient digestibility, small intestinal morphology, intestinal microflora, immune properties and antioxidant activities in weaned pigs. Pigs received a low-energy diet (negative control, NC, digestible energy = 3250 kcal/kg), NC plus 0.025% EO or a positive control diet (PC, digestible energy = 3400 kcal/kg) for 28 days. Growth performance was similar between the EO group and PC group. However, EO supplementation increased (P < 0.05) average daily gain and the apparent digestibility of dry matter, crude protein and energy compared with pigs fed the NC diet. Greater (P < 0.05) villus height and lower (P < 0.05) counts of Escherichia coli and total anaerobes in the rectum in the EO group were observed compared with NC or PC groups. Pigs fed EO diet had higher (P < 0.05) concentrations of albumin, immunoglobulin A (IgA), IgG and total antioxidant capacity and lower fecal score than pigs fed the PC and NC diets. Above all, this study indicates that supplementation of EO to a low-energy pig diet has beneficial results and obtains similar performance compared with normal energy (PC) diet.

Seventy-two barrows (Landrace × Large White, initial BW of 4.9 ± 0.3 kg and 17 ± 3 d old) were used to determine if dietary chito-oligosaccharides can replace antibiotics as a means to reduce signs associated with infection in weaned pigs challenged with Escherichia coli. Pigs were assigned to 1 of 4 treatments in a randomized complete block design using 6 pens per treatment with 3 pigs per pen. The treatments consisted of pigs fed the unsupplemented corn-soybean meal diet challenged or unchallenged with E. coli K88 and pigs fed the same diet supplemented with 160 mg of chito-oligosaccharides or 100 mg of cyadox/kg and challenged with E. coli K88. On d 7, 1 group of pigs fed the unsupplemented diet, as well as all pigs fed diets containing chito-oligosaccharides or cyadox, were orally dosed with 30 mL of an alkaline broth containing E. coli K88. Another group of pigs fed the unsupplemented diet was orally dosed with 30 mL of sterilized alkaline broth. Fecal consistency was visually assessed each morning from d 7 to 14. Blood samples were collected at 0, 24, 48, and 168 h postinfection. On d 14 postchallenge, all pigs were killed to evaluate intestinal morphology and determine E. coli concentrations in the intestine. During the postchallenge period (wk 2), unsupplemented pigs challenged with E. coli had decreased (P < 0.05) BW gain, feed intake, fecal consistency, villus height, villus height:crypt depth ratio, and plasma IGF-1, and increased (P < 0.05) diarrhea incidence, E. coli counts in the intestine, plasma interleukin-1β, plasma IL-10, and IGA-positive cells in the jejunal and ileal lamina propria, compared with unchallenged pigs. Supplementation with cyadox largely mitigated these effects. Although chito-oligosaccharide reduced the incidence of diarrhea, the growth performance of E. coli-challenged pigs supplemented with chito-oligosaccharide was not better than that of unsupplemented pigs challenged with E. coli. Therefore, chito-oligosaccharide, at the amount used in this experiment, does not seem to be an effective substitute for antibiotics as a growth promoter for newly weaned pigs challenged with E. coli.

This study was conducted to test the hypothesis that different dietary Met levels affect small-intestinal mucosal integrity in post-weaning piglets. Two groups of piglets (n = 6/group) were weaned at 28 days of age and randomly allotted to a basal diet (without extra Met supplementation) or a Met-supplemented diet (with 0.12% L-Met) for 14 days. The standardized ileal digestible (SID) Met levels were 0.24 and 0.35%, respectively. At days 7 and 14 of the trial, venous blood samples were obtained from piglets, followed by their euthanasia for tissue collection. Piglets fed the diet supplemented with L-Met had a higher average daily gain during days 7-14 and improved feed efficiency during the entire period. Concentrations of sulfur amino acids (SAA), glutamate acid (Glu), glutamine (Gln), and taurine in the plasma and tissues were higher for the piglets in the Met-supplemented group. Met supplementation increased cysteine (Cys) and glutathione (GSH) concentrations in the plasma and tissues, leading to reductions in plasma Cys/CySS redox potential and tissue GSH/GSSH redox potential. The small-intestinal mucosa of Met-supplemented piglets exhibited improved villus architecture, compared with control piglets. Met supplementation increased transepithelial electrical resistance of the jejunal mucosa. Transport of Met, Gln and Cys across the jejunal mucosa did not differ between control and Met-supplemented piglets. The abundance occludin was higher, whereas the abundance of active caspase-3 was lower, in the jejunum of the Met-supplemented piglets. Collectively, adequate dietary Met is required for optimal protein synthesis and mucosal integrity in the small intestine of post-weaning piglets.