We investigated whether spray-dried plasma (SDP) improved growth and health of piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). Forty-eight pigs weaned at 21 d (BW = 4.88 +/- 0.43 kg) received one of four diets containing 6% SDP or fish proteins (as-fed basis) either nonmedicated (SDP-NM and FP-NM diets) or medicated with 0 or 250 mg/kg of colistine + 500 mg/kg of amoxycycline (SDP-M and FP-M diets), for 15 d. On d 4, pigs were orally challenged with ETEC. On d 15, eight pigs per dietary group were killed, blood and saliva were collected for analysis of K88 fimbriae-specific immunoglobulin (Ig)-A, and jejunum was removed for villi preparation, histological analysis, and cytokine expression. The presence or absence of K88 receptors (K88+ and K88- pigs respectively) was determined by villous adhesion assay. Effects of protein source on ADG (P = 0.04) and ADFI (P < 0.01), as well of medication on ADFI (P < 0.02), of all pigs were observed. In sacrified pigs, there was an effect of protein source on ADG (P = 0.03) and ADFI (P < 0.001), as well an interaction between medication and presence of K88 receptor (P = 0.02) for feed:gain ratio. Plasma K88 specific IgA were low in all K88 pigs and higher in K88+ pigs fed FP-NM compared with all the other groups (P < 0.05), except SDP-M. An interaction was found among protein source, medication, and presence of K88 receptors (P = 0.04). Saliva IgA concentrations were high in all pigs fed FP-NM and low in all other pigs. Jejunum of pigs fed FP-NM showed some ulcerations, edema, and mild inflammatory cell infiltration (ICI). In pigs fed FP-M, edema was reduced. Conversely, only a mild ICI was observed in pigs fed SDP-NM and SDP-M. Crypt depth was increased in K88+ pigs fed SDP-NM and an interaction between protein source and presence of K88 receptors was observed (P < 0.05). Expressions of tumor necrosis factor-alpha and interleukin (IL)-8 were lower in pigs fed SDP-NM and SDP-M than in those fed FP-NM and FP-M, either K88- or K88+ (P < 0.01). In pigs fed FP diets, expression of IL-8 tended to increase (P = 0.08) in K88+ compared with K88- subjects. Expression of interferon-gamma increased in K88 and K88+ pigs fed FP-M as compared with other pigs (P < 0.01). These results indicate that feeding with SDP improved growth performance and protected against E. coli-induced inflammatory status, and suggest that use of SDP-NM can be considered a valid antibiotic alternative.

Reducing the CP content and increasing the fermentable carbohydrates (FC) content of the diet may counteract the negative effects of protein fermentation in newly weaned piglets fed high-CP diets. To study the synergistic effects of CP and FC on gut health and its consequences for growth performance, 272 newly weaned piglets (26 d of age, 8.7 kg of BW) were allotted to 1 of 4 dietary treatments in a 2 x 2 factorial arrangement, with low and high CP and low and high FC content as the factors. Eight piglets from each dietary treatment were killed on d 7 postweaning. Feces and digesta from ileum and colon were collected to determine nutrient digestibility, fermentation products, and microbial counts. In addition, jejunum tissues samples were collected for intestinal morphology and enzyme activity determination. During the entire 4-wk period, interactions between the dietary CP and FC contents were found for ADFI (P = 0.022), ADG (P = 0.001), and G:F (P = 0.033). The high-FC content reduced ADFI, ADG, and G:F in the low-CP diet, whereas the FC content did not affect growth performance in the high-CP diet. Lowering the CP content of the low-FC diet improved ADFI and ADG, whereas lowering the CP content of the high-FC diet did not influence growth performance. The low-CP diets resulted in a lower concentration of ammonia in the small intestine (P = 0.003), indicating reduced protein fermentation. In the small intestine, the high FC content increased the number of lactobacilli (P = 0.047), tended to decrease the number of coliforms (P = 0.063), tended to increase the lactic acid content (P = 0.080), and reduced the concentration of ammonia (P = 0.049). In the colon, the high-FC diets increased the concentration of total VFA (P = 0.009), acetic acid (P = 0.003), and butyric acid (P = 0.018), and tended to decrease the ammonia concentration (P = 0.076). Intestinal morphology and activity of brush border enzymes were not affected by the diet, although maltase activity tended to decrease with increasing dietary FC (P = 0.061). We concluded that an increase in the dietary FC content, and to a lesser extent a decrease in the CP content, reduced ammonia concentrations and altered the microflora and fermentation patterns in the gastrointestinal tract of weaned piglets. However, these effects were not necessarily reflected by an increased growth performance of the piglets.

The microbial community in the guts of mammals is often seen as an important potential target in therapeutic and preventive interventions. The aim of the present study was to determine whether enterotoxigenic Escherichia coli (ETEC) F4 infection in young animals might be counteracted by a probiotic treatment with Lactobacillus sobrius DSM 16698. The experiment was conducted in three randomized consecutive replications, each consisting of 16 piglets, and including a control group and an L. sobrius fed group, both experimentally challenged with ETEC. During the entire trial, the animals' health status, body weight, and microbial parameters were monitored periodically. Probiotic supplementation containing L. sobrius significantly reduced the levels of ETEC in the ileum when fed directly to piglets after weaning. In contrast, the number of days when the piglets had an increased faecal water content was significantly higher in the probiotic group. Nevertheless, an improved daily weight gain was also observed in the animals that received probiotic L. sobrius relative to the control fed group. The data indicate that L. sobrius may be effective in the reduction of the E. coli F4 colonization and may improve the weight gain of infected piglets.

The enterotoxigenic Escherichia coli (ETEC) expressing F4 and F18 fimbriae are the two main pathogens associated with post-weaning diarrhea (PWD) in piglets. The growing global concern regarding antimicrobial resistance (AMR) has encouraged research into the development of nutritional and feeding strategies as well as vaccination protocols in order to counteract the PWD due to ETEC. A valid approach to researching effective strategies is to implement piglet in vivo challenge models with ETEC infection. Thus, the proper application and standardization of ETEC F4 and F18 challenge models represent an urgent priority. The current review provides an overview regarding the current piglet ETEC F4 and F18 challenge models; it highlights the key points for setting the challenge protocols and the most important indicators which should be included in research studies to verify the effectiveness of the ETEC challenge. Based on the current review, it is recommended that the setting of the model correctly assesses the choice and preconditioning of pigs, and the timing and dosage of the ETEC inoculation. Furthermore, the evaluation of the ETEC challenge response should include both clinical parameters (such as the occurrence of diarrhea, rectal temperature and bacterial fecal shedding) and biomarkers for the specific expression of ETEC F4/F18 (such as antibody production, specific F4/F18 immunoglobulins (Igs), ETEC F4/F18 fecal enumeration and analysis of the F4/F18 receptors expression in the intestinal brush borders). On the basis of the review, the piglets’ response upon F4 or F18 inoculation differed in terms of the timing and intensity of the diarrhea development, on ETEC fecal shedding and in the piglets’ immunological antibody response. This information was considered to be relevant to correctly define the experimental protocol, the data recording and the sample collections. Appropriate challenge settings and evaluation of the response parameters will allow future research studies to comply with the replacement, reduction and refinement (3R) approach, and to be able to evaluate the efficiency of a given feeding, nutritional or vaccination intervention in order to combat ETEC infection.

Sodium butyrate (SB) is used as an acidifier in animal feed. We hypothesized that supplemental SB impacts gastric morphology and function, depending on the period of SB provision. The effect of SB on the oxyntic and pyloric mucosa was studied in 4 groups of 8 pigs, each supplemented with SB either during the suckling period (d 4-28 of age), after weaning (d 29 to 39-40 of age) or both, or never. We assessed the number of parietal cells immunostained for H+/K+-ATPase, gastric endocrine cells immunostained for chromogranin A and somatostatin (SST) in the oxyntic mucosa, and gastrin-secreting cells in the pyloric mucosa. Gastric muscularis and mucosa thickness were measured. Expressions of the H+/K+-ATPase and SST type 2 receptor (SSTR2) genes in the oxyntic mucosa and of the gastrin gene in the pyloric mucosa were evaluated by real-time RT-PCR. SB increased the number of parietal cells per gland regardless of the period of administration (P< 0.05). SB addition after, but not before, weaning increased the number of enteroendocrine and SST-positive cells (P < 0.01) and tended to increase gastrin mRNA (P = 0.09). There was an interaction between the 2 periods of SB treatment for the expression of H/K-ATPase and SSTR2 genes (P < 0.05). Butyrate intake after weaning increased gastric mucosa thickness (P < 0.05) but not muscularis. SB used orally at a low dose affected gastric morphology and function, presumably in relationship with its action on mucosal maturation and differentiation.

We tested the effect of Trp addition to a standard weaning diet and oral challenge with enterotoxigenic Escherichia coli K88 (ETEC) on growth and health of piglets susceptible or nonsusceptible to the intestinal adhesion of ETEC. Sixty-four pigs weaned at 21 d of age were divided into 3 groups based on their ancestry and BW: a control group of 8 pigs fed a basal diet (B), the first challenged group of 28 pigs fed B diet (BCh), and the second challenged group of 28 pigs fed a diet with Trp (TrpCh). The Trp diet was produced by the addition of 1 g of l-Trp/kg to the basal diet. On d 5, pigs were orally challenged with 1.5 mL suspension containing 10(10) cfu ETEC/mL or placebo, and killed on d 9 or 23. Based on in vitro villus adhesion assay, the pigs (except the B group) were classified as susceptible (s(+)) or nonsusceptible (s(-)) to the intestinal ETEC adhesion. Thus, after the challenge, treatments were B, BChs(-), BChs(+), TrpChs(-), and TrpChs(+). Pigs susceptible to ETEC were 50.0% in the BChs(+) group (3 pigs lost included) and 46.4% in the TrpChs (+) group (1 pig lost included). During the first 4 d after challenge, the challenge reduced ADG (P< 0.05), and this reduction was greater in susceptible pigs (P < 0.05) than nonsusceptible ones. Tryptophan increased ADG and feed intake in susceptible pigs (P < 0.05) from challenge to d 4, but not thereafter. Tryptophan supplementation did not improve the fecal consistency and did not reduce the number of pigs positive for ETEC in feces on d 4 after the challenge. The K88-specific immunoglobulin A activity in blood serum tended to be greater in challenged pigs (P = 0.102) and was not affected by the addition of Trp. Villous height was affected by the addition of Trp and challenge in different ways, depending on the site of small intestine. The need to consider the phenotype for the adhesion of the ETEC in studies with different supply of Trp was clearly evident. When compared with practical weaning standard diets, Trp supplementation allowed susceptible pigs to partially compensate for the effects of ETEC challenge by increasing feed intake and maintaining an adequate BW growth. This is of practical importance for the formulation of diets for pigs selected for lean growth because of the presence of an association between this trait and the susceptibility to the intestinal adhesion of ETEC.

Antibiotic resistance is a public health problem of growing concern. Animal manure application to soil is considered to be a main cause of the propagation and dissemination of antibiotic residues, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) in the soil-water system. In recent decades, studies on the impact of antibioticcontaminated manure on soil microbiomes have increased exponentially, in particular for taxonomical diversity and ARGs' diffusion. Antibiotic resistance genes are often located on mobile genetic elements (MGEs). Horizontal transfer of MGEs toward a broad range of bacteria (pathogens and human commensals included) has been identified as the main cause for their persistence and dissemination. Chemical and bio-sanitizing treatments reduce the antibiotic load and ARB. Nevertheless, effects of these treatments on the persistence of resistance genes must be carefully considered. This review analyzed the most recent research on antibiotic and ARG environmental dissemination conveyed by livestock waste. Strategies to control ARG dissemination and antibiotic persistence were reviewed with the aim to identify methods for monitoring DNA transferability and environmental conditions promoting such diffusion.

The relevance of the butyrate-sensing olfactory receptor OR51E1 for gastrointestinal (GIT) functioning has not been considered so far. We investigated in young pigs the distribution of OR51E1 along the GIT, its relation with some endocrine markers, its variation with age and after interventions affecting the gut environment and intestinal microbiota. Immuno-reactive cells for OR51E1 and chromogranin A (CgA) were counted in cardial (CA), fundic (FU), pyloric (PL) duodenal (DU), jejunal (JE), ileal (IL), cecal (CE), colonic (CO) and rectal (RE) mucosae. OR51E1 co-localization with serotonin (5HT) and peptide YY (PYY) were evaluated in PL and CO respectively. FU and PL tissues were also sampled from 84 piglets reared from sows receiving either or not oral antibiotics (amoxicillin) around parturition, and sacrificed at days 14, 21, 28 (weaning) and 42 of age. JE samples were also obtained from 12 caesarean-derived piglets that were orally associated with simple (SA) or complex (CA) microbiota in the postnatal phase, and of which on days 26–37 of age jejunal loops were perfused for 8 h with enterotoxigenic Escherichia coli F4 (ETEC), Lactobacillus amylovorus or saline (CTRL). Tissue densities of OR51E1+ cells were in decreasing order: PL=DU>FU=CA>JE=IL=CE=CO=RE. OR51E1+ cells showed an enteroendocrine nature containing gastrointestinal hormones such as PYY or 5HT. OR51E1 gene expression in PL and FU increased during and after the suckling period (p<0.05). It was marginally reduced in offspring from antibiotic-treated sows (tendency, p=0.073), vs. control. Jejunal OR51E1 gene expression was reduced in piglets early associated with SA, compared with CA, and in ETEC-perfused loops vs. CTRL (p<0.01). Our results indicate that OR51E1 is related to GIT enteroendocrine activity. Moreover age, pathogen challenge and dietary manipulations influencing the gastrointestinal luminal microenvironment significantly affect the OR51E1 gene expression in GIT tissues presumably in association with the release of microbial metabolites.