Suspected aerosol transmission of swine pathogens: A field case.

A swine production system had 3 sections located a few kilometers apart. Sections A and C contained several thousand sows and nursery and finishing pigs. Section B, located between the other 2 sections, was the smallest and had 6 finishing sites and 2 sow sites. The entire system was infected with porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and Actinobacillus pleuropneumoniae. Section B was depopulated, cleaned, disinfected, and repopulated with negative gilts. Despite extreme measures, recontamination occurred for each pathogen, with aerosol considered the most plausible contamination source.

Transmission suspectée d'agents pathogènes porcins par aérosol : un cas de terrainUn système de production porcine comportait 3 sections situées à quelques kilomètres l'une de l'autre. Les sections A et C contenaient plusieurs milliers de truies et de porcs en maternité et en finition. La section B, située entre les 2 autres sections, était la plus petite et comptait 6 sites de finition et 2 sites de truies. L'ensemble du système était infecté par le virus du syndrome reproducteur et respiratoire porcin, Mycoplasma hyopneumoniae et Actinobacillus pleuropneumoniae. La section B a été dépeuplée, nettoyée, désinfectée et repeuplée de cochettes négatives. Malgré des mesures extrêmes, une recontamination s'est produite pour chaque agent pathogène, les aérosols étant considérés comme la source de contamination la plus plausible.(Traduit par Dr Serge Messier).

Surface display of the COE antigen of porcine epidemic diarrhoea virus on Bacillus subtilis spores.

Porcine epidemic diarrhoea virus (PEDV) infects pigs of all ages by invading small intestine, causing acute diarrhoea, vomiting, and dehydration with high morbidity and mortality among newborn piglets. However, current PEDV vaccines are not effective to protect the pigs from field epidemic strains because of poor mucosal immune response and strain variation. Therefore, it is indispensable to develop a novel oral vaccine based on epidemic strains. Bacillus subtilis spores are attractive delivery vehicles for oral vaccination on account of the safety, high stability, and low cost. In this study, a chimeric gene CotC-Linker-COE (CLE), comprising of the B. subtilis spore coat gene cotC fused to the core neutralizing epitope CO-26 K equivalent (COE) of the epidemic strain PEDV-AJ1102 spike protein gene, was constructed. Then recombinant B. subtilis displaying the CLE on the spore surface was developed by homologous recombination. Mice were immunized by oral route with B. subtilis 168-CLE, B. subtilis 168, or phosphate-buffered saline (PBS) as control. Results showed that the IgG antibodies and cytokine (IL-4, IFN-γ) levels in the B. subtilis 168-CLE group were significantly higher than the control groups. This study demonstrates that B. subtilis 168-CLE can generate specific systemic immune and mucosal immune responses and is a potential vaccine candidate against PEDV infection.

Lactiplantibacillus argentoratensis AGMB00912 alleviates salmonellosis and modulates gut microbiota in weaned piglets: a pilot study.

This study aimed to evaluate the efficacy of Lactiplantibacillus argentoratensis AGMB00912 (LA) in reducing Salmonella Typhimurium infection in weaned piglets. The investigation focused on the influence of LA on the gut microbiota composition, growth performance, and Salmonella fecal shedding. The results indicated that LA supplementation significantly improved average daily gain and reduced the prevalence and severity of diarrhea. Fecal analysis revealed reduced Salmonella shedding in the LA-supplemented group. Furthermore, LA notably altered the composition of the gut microbiota, increasing the levels of beneficial Bacillus and decreasing those of harmful Proteobacteria and Spirochaetes. Histopathological examination showed less intestinal damage in LA-treated piglets than in the controls. The study also observed that LA affected metabolic functions related to carbohydrate, amino acid, and fatty acid metabolism, thereby enhancing gut health and resilience against infection. Short-chain fatty acid concentrations in the feces were higher in the LA group, suggesting improved gut microbial activity. LA supplementation enriched the population of beneficial bacteria, including Streptococcus, Clostridium, and Bifidobacterium, while reducing the number of harmful bacteria, such as Escherichia and Campylobacter. These findings indicate the potential of LA as a probiotic alternative for swine nutrition, offering protective effects to the gut microbiota against Salmonella infection.

Acute Ascaris infection impairs the effector functions of natural killer cells in single and Salmonella co-infected pigs.

Natural killer (NK) cells play a key role in defense against Salmonella infections during the early phase of infection. Our previous work showed that the excretory/secretory products of Ascaris suum repressed NK activity in vitro. Here, we asked if NK cell functionality was influenced in domestic pigs during coinfection with Ascaris and Salmonella enterica serotype Typhimurium. Ascaris coinfection completely abolished the IL-12 and IL-18 driven elevation of IFN-γ production seen in CD16 + CD8α + perforin + NK cells of Salmonella single-infected pigs. Furthermore, Ascaris coinfection prohibited the Salmonella-driven rise in NK perforin levels and CD107a surface expression. In line with impaired effector functions, NK cells from Ascaris-single and coinfected pigs displayed elevated expression of the inhibitory KLRA1 and NKG2A receptors genes, contrasting with the higher expression of the activating NKp46 and NKp30 receptors in NK cells during Salmonella single infection. These differences were accompanied by the highly significant upregulation of T-bet protein expression in NK cells from Ascaris-single and Ascaris/Salmonella coinfected pigs. Together, our data strongly indicate a profound repression of NK functionality by an Ascaris infection which may hinder infected individuals from adequately responding to a concurrent bacterial infection.

First molecular detection of Brachyspira hampsonii on pig farms in Poland.

Nowadays, the three strongly beta-haemolytic spirochaetes, Brachyspira hyodysenteriae, Brachyspira suanatina and Brachyspira hampsonii are thought to be causative agents of swine dysentery, an economically devastating disease of grow-finish pigs characterised by severe mucohaemorrhagic diarrhoea. B. hyodysenteriae has been reported in most leading swine-producing regions. B. suanatina and B. hampsonii have been successfully recovered from faecal samples collected in a few countries only. The present study was performed in March 2023 on faecal samples originating from nine Polish finisher farms with 6,000 to 18,000 animals in a location. Samples were obtained from 40 diarrhoeic finishers. Nucleic acid extracted from the samples was analysed using multiplex PCR for Brachyspira spp. From a total of nine sample populations examined in our study, the genetic material of B. hampsonii was identified in two. To the best of our knowledge, this is the first report on molecular detection of B. hampsonii on pig farms outside North America, Belgium and Germany. Our research highlights the need for increased focus directed on laboratory testing strategies, the lack of which may perplex swine practitioners and severely hinder a definite diagnosis.

Pathogenic profile and antimicrobial resistance of Escherichia coli, Escherichia marmotae and Escherichia ruysiae detected from hunted wild boars in Sardinia (Italy).

The objective of this study was to evaluate the occurrence of E. coli in hunted wild boars in Sardinia (Italy) and to further characterize the isolates with Whole Genome Sequencing to assess the genetic relatedness and the presence of virulence and antimicrobial resistance (AMR) genes. Samples were taken from 66 wild boars between 2020 and 2022 slaughtered in five hunting houses. A total of 181 samples were tested, including 66 samples from mesenteric lymph nodes, 66 samples from colon content and 49 samples from carcass surface. Isolates referable to Escherichia species were detected in all of the wild boars sampled. On a selection of 61 isolates, sequencing was conducted and antimicrobial susceptibility was tested. Among these, three isolates were confirmed to be two Escherichia marmotae (cryptic clade V) and one Escherichia ruysiae (cryptic clade III). E. coli pathotypes identified were UPEC (13 %), ExPEC-UPEC (5.6 %) and ETEC (3.7 %). Moreover, 3/6 E. marmotae isolates had typical ExPEC genes. Genetic similarity was observed in isolates collected from animals slaughtered in the same hunting house; this suggests epidemiological links deriving from the presence of animals infected with closely related strains or the result of cross-contamination. Antimicrobial resistance genes were detected in three non-pathogenic E. coli isolates: one isolate had sul2, tet(B), aph(6)-ld and aph(3″)-lb resistance genes and two had the fosA7 gene. This study confirmed that wild boars can act as reservoirs and spreaders of pathogenic Escherichia species and it provides information for future comparative genomic analysis in wildlife. Although isolates showed a limited resistome, the detection of resistance in non-pathogenic isolates underlines the need to monitor antimicrobial resistance in the wild boar population. To the best of our knowledge, this is the first detection of E. mamotae and E. ruysiae isolates in wild boars in Italy and the presence of this pathogen in wildlife and livestock need to be investigated further.

Analysis of the Nasal Microbiota in Healthy and Diseased Pigs.

Massive sequencing of a fragment of 16S rRNA gene allows the characterization of bacterial communities in different body sites: the microbiota. Nasal microbiota can be analyzed by DNA extraction from nasal swabs, amplification of the specific fragment of interest, and posterior sequencing. The raw sequences obtained need to go through a computational process to check their quality and then assign the taxonomy. Here, we will describe the complete process from sampling to get the microbial diversity of nasal microbiota in health and disease.

Evaluation of the Economic Impact of Streptococcus suis-Associated Disease.

The economic impact of Streptococcus suis-associated disease at farm level is well known by the producers, but the cost in a region or a country is more difficult to evaluate due to the lack of a centralized data system, the different incidences, and the control measures applied by each producer. In this chapter, we describe a method based on the information gathered through interviews with veterinary practitioners. A comprehensive questionnaire created specifically for the disease can help to conduct the interviews. The questions include information about the proportions of farms, batches and animals clinically affected, mortality, metaphylactic and therapeutic treatments, use of vaccines, and proportion of cases that are diagnosed at the laboratory. As the questionnaire is quite complex, the best option to obtain the data is send the questionnaire to the selected veterinarians to allow them to collect some data and make an interview with them some days later. The information allows to estimate the costs due to mortality, antimicrobial treatments, the use of autogenous vaccines, and analyses performed. Initially they are calculated per animal in each affected production phase, and later it can be extrapolated to estimate the annual cost per affected production unit and per country. The model does not consider indirect costs such as the cost as a zoonosis, the revenues forgone, or an increase of labor.

Experimental Intraperitoneal Infection of Piglets.

Streptococcus suis is a swine bacterial pathogen that predominantly causes disease in weaned piglets characterized by swelling of joints, arthritis, septicemia, meningitis, and sudden death. Intravenous, intramuscular, intraperitoneal, and intranasal infection models were developed to study the bacterial pathogenicity and efficacy of vaccines and various therapeutics. The selection of the appropriate infection model is a critical step in any study, as it may impact the outcomes of the study. Here we describe a method for infecting weaned piglets with S. suis using intraperitoneal route as a reliable, consistent, and reproducible animal model to evaluate vaccine protection against systemic bacterial infection.

Preparation and Study of Bacterins.

Streptococcus suis is a bacterial pathogen that can cause significant economic losses in the swine industry due to high morbidity and mortality rates in infected animals. Vaccination with bacterins, which consist of inactivated bacteria and adjuvants to enhance the pig's immune response, is an effective approach to control S. suis infections in piglets. Here we provide a description of S. suis bacterins and the methods for vaccine preparation. Moreover, this chapter also describes the addition of recombinant Sao (rSao-L) protein to the S. suis bacterin, aiming to enhance the efficacy of the bacterins against S. suis in piglets. Furthermore, the methods for evaluating the immune response elicited by the bacterins are also covered in this chapter.

Effects of Antrodia cinnamomea solid culture mycelium by-products on growth performance and immune response in weaning black piglets.

This study evaluated the effects of supplementation with Antrodia cinnamomea mycelium by-product (ACBP) on growth performance and immune response in weaning piglets. Total available content and antioxidant capacity of ACBP were determined. Ninety-six black pigs were randomly distributed to 24 pens. Study compared four groups which were supplemented with ACBP at 0%, 2.5%, 5%, or 10% for 6 weeks after weaning at 4 weeks. Results showed that ACBP on total phenolic, total flavonoid, and total triterpenoids contents were 13.68 mg GAE/g DW, 1.67 µg QE/g DW, and 15.6 mg/g, respectively. Weaning piglets fed 2.5% ACBP showed a significant decreased body weight gain compared with those supplemented with 5% ACBP, 10% ACBP, and control groups. Results showed that all ACBP groups increased the villi height of jejunum significantly. Incidence of diarrhea in 11 weeks with supplementation with 5% and 10% ACBP diets were lower than in control group. The 10% ACBP group showed significantly lower expression of immune response genes (IL-1ß, IL-6, IL-8, TNF-α, and IFN-γ) than the 2.5% and 5% ACBP groups. Based on results, dietary supplementation with 10% ACBP did not significantly affect body weight but could decrease piglet diarrhea condition and expression of IL-1ß and IL-6 genes.

Whole genome sequencing analysis on antibiotic-resistant Escherichia coli isolated from pig farms in Banten Province, Indonesia.

IMPORTANCE: The emergence and rapid increase in the incidence of multidrug-resistant (MDR) bacteria in pig farms has become a serious concern and reduced the choice of effective antibiotics. OBJECTIVE: This study analyzed the phylogenetics and diversity of antibiotic resistance genes (ARGs) and molecularly identified the source of ARGs in antibiotic-resistant Escherichia coli isolated from pig farms in Banten Province, Indonesia. METHODS: Forty-four antibiotic-resistant E. coli isolates from fecal samples from 44 pig farms in Banten Province, Indonesia, were used as samples. The samples were categorized into 14 clusters. Sequencing was performed using the Oxford Nanopore Technologies MinION platform, with barcoding before sequencing with Nanopore Rapid sequencing gDNA-barcoding (SQK-RBK110.96) according to manufacturing procedures. ARG detection was conducted using ResFinder, and the plasmid replicon was determined using PlasmidFinder. RESULTS: Three phylogenetic leaves of E. coli were identified in the pig farming cluster in Banten Province. The E. coli isolates exhibited potential resistance to nine classes of antibiotics. Fifty-one ARGs were identified across all isolates, with each cluster carrying a minimum of 10 ARGs. The ant(3'')-Ia and qnrS1 genes were present in all isolates. ARGs in the E. coli pig farming cluster originated mainly from plasmids, accounting for an average of 89.4%. CONCLUSIONS AND RELEVANCE: The elevated potential for MDR events, coupled with the dominance of ARGs originating from plasmids, increases the risk of ARG spread among bacterial populations in animals, humans, and the environment.

Evaluation the kill rate and mutant selection window of danofloxacin against Actinobacillus pleuropneumoniae in a peristaltic pump model.

BACKGROUND: Actinobacillus pleuropneumoniae is a serious pathogen in pigs. The abundant application of antibiotics has resulted in the gradual emergence of drugresistant bacteria, which has seriously affected treatment of disease. To aid measures to prevent the emergence and spread of drug-resistant bacteria, herein, the kill rate and mutant selection window (MSW) of danofloxacin (DAN) against A. pleuropneumoniae were evaluated. METHODS: For the kill rate study, the minimum inhibitory concentration (MIC) was tested using the micro dilution broth method and time-killing curves of DAN against A. pleuropneumoniae grown in tryptic soy broth (TSB) at a series drug concentrations (from 0 to 64 MIC) were constructed. The relationships between the kill rate and drug concentrations were analyzed using a Sigmoid Emax model during different time periods. For the MSW study, the MIC99 (the lowest concentration that inhibited the growth of the bacteria by ≥ 99%) and mutant prevention concentration (MPC) of DAN against A. pleuropneumoniae were measured using the agar plate method. Then, a peristaltic pump infection model was established to simulate the dynamic changes of DAN concentrations in pig lungs. The changes in number and sensitivity of A. pleuropneumoniae were measured. The relationships between pharmacokinetic/pharmacodynamic parameters and the antibacterial effect were analyzed using the Sigmoid Emax model. RESULTS: In kill rate study, the MIC of DAN against A. pleuropneumoniae was 0.016 µg/mL. According to the kill rate, DAN exhibited concentration-dependent antibacterial activity against A. pleuropneumoniae. A bactericidal effect was observed when the DAN concentration reached 4-8 MIC. The kill rate increased constantly with the increase in DAN concentration, with a maximum value of 3.23 Log10 colony forming units (CFU)/mL/h during the 0-1 h period. When the drug concentration was in the middle part of the MSW, drugresistant bacteria might be induced. Therefore, the dosage should be avoided to produce a mean value of AUC24h/MIC99 (between 31.29 and 62.59 h. The values of AUC24h/MIC99 to achieve bacteriostatic, bactericidal, and eradication effects were 9.46, 25.14, and > 62.59 h, respectively. CONCLUSION: These kill rate and MSW results will provide valuable guidance for the use of DAN to treat A. pleuropneumoniae infections.

Characterization and the first complete genome sequence of a novel strain of Bergeyella porcorum isolated from pigs in China.

BACKGROUND: Bergeyella porcorum is a newly identified bacterium that has an ambiguous relationship with pneumonia in pigs. However, few studies have adequately characterized this species. RESULTS: In this study, we analyzed the morphological, physiological, and genomic characteristics of the newly identified B. porcorum sp. nov. strain QD2021 isolated from pigs. The complete genome sequence of the B. porcorum QD2021 strain consists of a single circular chromosome (2,271,736 bp, 38.51% G + C content), which encodes 2,578 genes. One plasmid with a size of 70,040 bp was detected. A total of 121 scattered repeat sequences, 319 tandem repeat sequences, 4 genomic islands, 5 prophages, 3 CRISPR sequences, and 51 ncRNAs were predicted. The coding genes of the B. porcorum genome were successfully annotated across eight databases (NR, GO, KEGG, COG, TCDB, Pfam, Swiss-Prot and CAZy) and four pathogenicity-related databases (PHI, CARD, VFDB and ARDB). In addition, a comparative genome analysis was performed to explore the evolutionary relationships of B. porcorum QD2021. CONCLUSIONS: To our knowledge, this is the first study to provide fundamental phenotypic and whole-genome sequences for B. porcorum. Our results extensively expand the current knowledge and could serve as a valuable genomic resource for future research on B. porcorum.

Study of the therapeutic efficacy of DOKSI AVZ 500 in bacterial respiratory diseases in young pigs.

Background: Young farm animals are susceptible to opportunistic infections which may cause economic losses due to mortality and poor weight gain. The development of antimicrobial resistance and the desire to improve therapy efficacy and safety are the reasons to seek for new antibacterial drugs ensuring rapid recovery with minimum adverse events. Aim: To estimate the efficacy of DOKSI AVZ 500 in respiratory pathologies in young pigs. Methods: The study was conducted in 65-70-day-old Yorkshire piglets with signs of bacterial respiratory pathologies. The animals were treated with the test drug for 3 or 5 days. The reference group received TETRAMAX 500 which is similar to the test drug in terms of chemical structure, mechanism of action, and activity spectrum. The animal's status was assessed using clinical examination, clinical blood count, and bacteriological tests. Results: Both test and reference drugs were well tolerated and ensured the animal recovery within about 4 days. The recovery was accompanied by normalization of hematological parameters and flora composition. The bacterium associated with the disease development, Streptococcus suis, was virtually completely eliminated in all groups. No adverse events were noted. After the treatment, all the animals readily gained weight and live market quality. Conclusion: DOKSI AVZ 500 was a highly efficient therapy for respiratory pathologies caused by the resident opportunistic flora in piglets. It has also shown noninferiority vs. TETRAMAX 500 in terms of all the health-related parameters and thus can be recommended for introduction in veterinary practice in pig farms.

Small mammals as carriers of zoonotic bacteria on pig and cattle farms - Prevalence and risk of exposure in an integrative approach.

To prevent foodborne infections from pigs and cattle, the whole food chain must act to minimize the contamination of products, including biosecurity measures which prevent infections via feed and the environment in production farms. Rodents and other small mammals can be reservoirs of and key vectors for transmitting zoonotic bacteria and viruses to farm animals, through direct contact but more often through environmental contamination. In line with One Health concept, we integrated results from a sampling study of small mammals in farm environments and data from a capture-recapture experiment into a probabilistic model which quantifies the degree of environmental exposure of zoonotic bacteria by small mammals to farm premises. We investigated more than 1200 small mammals trapped in and around 38 swine and cattle farm premises in Finland in 2017/2018. Regardless of the farm type, the most common species caught were the yellow-necked mouse (Apodemus flavicollis), bank vole (Clethrionomys glareolus), and house mouse (Mus musculus). Of 554 intestine samples (each pooled from 1 to 10 individuals), 33% were positive for Campylobacter jejuni. Yersinia enterocolitica was detected in 8% of the pooled samples, on 21/38 farm premises. Findings of Salmonella and the Shiga-toxin producing Escherichia coli (STEC) were rare: the pathogens were detected in only single samples from four and six farm premises, respectively. The prevalence of Campylobacter, Salmonella, Yersinia and STEC in small mammal populations was estimated as 26%/13%, 1%/0%, 2%/3%, 1%/1%, respectively, in 2017/2018. The exposure probability within the experimental period of four weeks on farms was 17-60% for Campylobacter and 0-3% for Salmonella. The quantitative model is readily applicable to similar integrative studies. Our results indicate that small mammals increase the risk of exposure to zoonotic bacteria in animal production farms, thus increasing risks also for livestock and human health.

Association of toxin-producing Clostridioides difficile with piglet diarrhea and potential transmission to humans.

The pathogenicity of Clostridioides difficile in piglets remains controversial. It is unknown whether C. difficile control helps protect piglet health. To clarify the association between C. difficile presence and piglet diarrhea, isolates were obtained from piglets with and without diarrhea. In addition, to determine the genetic relationship of C. difficile from pigs and humans, we performed whole-genome sequencing (WGS) of C. difficile isolates. Diarrheal and non-diarrheal stool samples were collected from neonatal piglets from five farms in Japan in 2021. To clarify the relationship between C. difficile derived from pigs and those from human clinical cases, WGS of C. difficile isolates was performed. Toxin-positive C. difficile were significantly more prevalent in piglets with diarrhea, although the overall frequency of C. difficile did not differ between piglets with and without diarrhea. This observation indicates an association between toxin-positive C. difficile and diarrhea in piglets. However, further studies are needed to establish a direct causal relationship and to explore other contributing factors to diarrhea in piglets. WGS results showed that C. difficile sequence type (ST) 11 including the hypervirulent PCR ribotype 078 isolates derived from Japanese pigs were closely related to ST11 of overseas strains (human clinical and animal-derived) and a Japanese human clinical strain. Toxin-positive C. difficile may cause diarrhea in piglets and hypervirulent C. difficile are spreading among pigs and human populations worldwide.

Effects of dietary yeast mannan-rich fraction supplementation on growth performance, intestinal morphology, and lymphoid tissue characteristics in weaned piglets challenged with Escherichia Coli F4.

We evaluated the effects of supplementing yeast mannan-reach-fraction on growth performance, jejunal morphology and lymphoid tissue characteristics in weaned piglets challenged with E. Coli F4. A total of 20 crossbred piglets were used. At weaning, piglets were assigned at random to one of four groups: piglets challenged and fed the basal diet supplemented with yeast mannan-rich fraction (C-MRF, n = 5); piglets challenged and fed the basal diet (C-BD, n = 5); piglets not challenged and fed the basal diet supplemented with yeast mannan-rich fraction (NC-MRF, n = 5), and piglets not challenged and fed the basal diet (NC-BD). Each dietary treatment had five replicates. On days 4, 5 and 10, piglets were orally challenged with 108 CFU/mL of E. Coli F4. C-MRF piglets had higher BW (p = 0.002; interactive effect) than C-BD piglets. C-MRF piglets had higher (p = 0.02; interactive effect) ADG in comparison with C-BD piglets. C-MRF piglets had higher (p = 0.04; interactive effect) ADFI than C-BD piglets. The diameter of lymphoid follicles was larger (p = 0.010; interactive effect) in the tonsils of C-MRF piglets than C-BD piglets. Lymphoid cells proliferation was greater in the mesenteric lymphnodes and ileum (p = 0.04 and p = 0.03, respectively) of C-MRF piglets. A reduction (p > 0.05) in E. Coli adherence in the ileum of piglets fed MRF was observed. In conclusion, the results of the present study demonstrate that dietary yeast mannan-rich fraction supplementation was effective in protecting weaned piglets against E. Coli F4 challenge.

Dietary supplementation with dihydroartemisinin improves intestinal barrier function in weaned piglets with intrauterine growth retardation by modulating the gut microbiota.

The aim of this study was to investigate whether dietary dihydroartemisinin (DHA) supplementation could improve intestinal barrier function and microbiota composition in intrauterine growth restriction (IUGR) weaned piglets. Twelve normal birth weight (NBW) piglets and 24 IUGR piglets at 21 d of age were divided into three groups, which were fed a basal diet (NBW-CON and IUCR-CON groups) and an 80 mg/kg DHA diet (IUGR-DHA group). At 49 d of age, eight piglets of each group with similar body weights within groups were slaughtered, and serum and small intestine samples were collected. The results showed that IUGR piglets reduced growth performance, impaired the markers of intestinal permeability, induced intestinal inflammation, decreased intestinal immunity, and disturbed the intestinal microflora. Dietary DHA supplementation increased average daily gain, average daily feed intake, and body weight at 49 d of age in IUGR-weaned piglets (P < 0.05). DHA treatment decreased serum diamine oxidase activity and increased the numbers of intestinal goblet cells and intraepithelial lymphocytes, concentrations of jejunal mucin-2 and ileal trefoil factor 3, and intestinal secretory immunoglobin A and immunoglobin G (IgG) concentrations of IUGR piglets (P < 0.05). Diet supplemented with DHA also upregulated mRNA abundances of jejunal IgG, the cluster of differentiation 8 (CD8), major histocompatibility complex-I (MHC-I), and interleukin 6 (IL-6) and ileal IgG, Fc receptor for IgG (FcRn), cluster of differentiation 8 (CD4), CD8, MHC-I, IL-6 and tumor necrosis factor α (TNF-α), and enhanced mRNA abundance and protein expression of intestinal occludin and ileal claudin-1 in IUGR piglets (P < 0.05). In addition, DHA supplementation in the diet improved the microbial diversity of the small intestine of IUGR piglets and significantly increased the relative abundance of Actinobacteriota, Streptococcus, Blautia and Streptococcus in the jejunum, and Clostridium sensu_ stricto_in the ileum (P < 0.05). The intestinal microbiota was correlated with the mRNA abundance of tight junction proteins and inflammatory response-related genes. These data suggested that DHA could improve the markers of intestinal barrier function in IUGR-weaned piglets by modulating gut microbiota. DHA may be a novel nutritional candidate for preventing intestinal dysfunction in IUGR pigs.

Intrauterine growth retardation (IUGR) is defined as the restricted development of the mammalian fetus or its organs during pregnancy, which has high morbidity and mortality during the perinatal period and improves the risk of metabolic diseases in the long term. Dihydroartemisinin (DHA) is a derivative of artemisinin that possesses anti-inflammatory and immunoregulatory effects. Therefore, this experiment was conducted to investigate whether dietary DHA supplementation could improve the intestinal barrier function and microbiota composition in IUGR-weaned piglets. The result showed that IUGR could lead to intestinal barrier dysfunction. Dietary supplementation with DHA improved growth performance and attenuated intestinal barrier dysfunction by decreasing the markers of intestinal permeability, increasing the mucus layer barrier, enhancing immunity, and reducing the inflammatory response in IUGR piglets, which may be attributed to the improvement of the intestinal microbiota. Moreover, the study indicated that the gut microflora was correlated with the gene expression of tight junction proteins and immune function. This study may provide a new nutritional strategy for the maintenance of intestinal health in IUGR pigs.