Progression of swine fecal microbiota during early stages of life and its association with performance: a longitudinal study.

BACKGROUND: It is vital to understand healthy gut microbiota composition throughout early life stages when environments are changing, and immunity is developing. There are limited large-scale longitudinal studies classifying healthy succession of swine microbiota. The objectives of this study were to (a) determine the microbiota composition of fecal samples collected from piglets within a few days after birth until one-week post-weaning, and (b) investigate the associations of early fecal microbiota with pig growth performance in nursery and later growing stages. Fecal samples were collected from nine cohorts of 40 pigs (n = 360) from distinct farrowing sources in Ontario and Quebec, Canada at four timepoints from birth to one-week post-weaning, with pig body weight was recorded at each fecal sampling. RESULTS: Microbiota was dominated by the phyla Firmicutes, Bacteroides and Proteobacteria. There were notable differences in genera abundance between pigs from different provinces and farming systems. Over the early life stage, the genera Bacteroides, Escherichia/Shigella, and Clostridium cluster XIVa were abundant preweaning, while Prevotella dominated post-weaning. Hierarchical clustering identified three major stages of microbiota development, each associated with distinct composition. Stage one occurs from birth to 7 days, stage two from 7 days after birth until weaning, and stage three from weaning to one-week post-weaning. Three enterotypes were identified in stage two that showed differences in growth before weaning, and in the grower production stage. Piglets with a microbiota enterotype characterized by higher abundance of Prevotella and unclassified Ruminococcaceae had lower growth performance in the pre-weaning stage, and the growing stage. CONCLUSION: These findings help identify the timing of microbiota shifts across early swine life which may be the optimal time for external intervention to shift the microbiota to a beneficial state. The project findings should help decrease antimicrobial use, increase animal welfare, and have positive economic impacts.

An investigation into fecal shedding of Streptococcus suis serotypes in nursery pigs.

Objective: The objective of this study was to monitor Streptococcus suis fecal shedding in nursery pigs on a farm with a history of S. suis disease involving serotypes 2 and 9. Animal and procedure: Four cohorts of pigs (n = 480) were monitored from weaning to end of nursery. Rectal swabs from 297 pigs were tested and S. suis serotypes 15 (n = 7), 31 (n = 3), or untypeable (n = 6) isolates were recovered from 16 (5.4%) pigs. Results: There was no significant association between S. suis fecal shedding and diarrhea. Streptococcus suis isolates recovered from pigs euthanized due to neurological signs or severe lameness were serotypes 9 (meninges) and 31 (tonsil) or untypeable (meninges, tonsil). Serotypes 9 (meninges, tonsil), 15 (spleen, tonsil), 16 (tonsil), 29 and 33 (nasal swabs), and untypeable (meninges, tonsil, and lung) isolates were identified in lame pigs. Conclusion and clinical relevance: These results suggest that feces may not be a source of infection for the S. suis serotypes producing disease in pigs; however, the association between S. suis fecal shedding and diarrhea needs further investigation. The coincidence of untypeable isolates in feces from healthy pigs and their isolation from meninges of pigs with neurological signs warrants further investigation to determine the molecular characteristics of those isolates.

Une enquête sur l'excrétion fécale des sérotypes de Streptococcus suis chez les porcelets en pouponnière. Objectif: L'objectif de cette étude était de surveiller l'excrétion fécale de Streptococcus suis chez des porcelets en pouponnière dans une ferme ayant des antécédents de maladie à S. suis impliquant les sérotypes 2 et 9. Animal et procédure: Quatre cohortes de porcs (n = 480) ont été suivies du sevrage jusqu'à la fin de la période en pouponnière. Des écouvillons rectaux provenant de 297 porcs ont été testés et des isolats de S. suis des sérotypes 15 (n = 7), 31 (n = 3) ou non-typables (n = 6) ont été récupérés chez 16 (5,4 %) porcs. Résultats: Il n'y avait aucune association significative entre l'excrétion fécale de S. suis et la diarrhée. Les isolats de S. suis récupérés chez des porcs euthanasiés en raison de signes neurologiques ou d'une boiterie sévère étaient de sérotypes 9 (méninges) et 31 (amygdales) ou non-typables (méninges, amygdales). Les sérotypes 9 (méninges, amygdales), 15 (rate, amygdales), 16 (amygdales), 29 et 33 (écouvillonnages nasaux) et des isolats non-typables (méninges, amygdales et poumons) ont été identifiés chez des porcs boitant. Conclusion et pertinence clinique: Ces résultats suggèrent que les matières fécales pourraient ne pas être une source d'infection pour les sérotypes de S. suis produisant des maladies chez les porcs; cependant, l'association entre l'excrétion fécale de S. suis et la diarrhée nécessite des recherches plus approfondies. La coïncidence d'isolats non-typables dans les selles de porcs sains et leur isolement dans les méninges de porcs présentant des signes neurologiques justifient des recherches plus approfondies pour déterminer les caractéristiques moléculaires de ces isolats.(Traduit par Dr Serge Messier).

Investigations into the effects of Escherichia coli vaccination and diet composition on post-weaning diarrhea and growth performance in pigs.

Objectives: Pigs often experience slow growth and enteric disease problems during the early post-weaning period. The objectives were to evaluate effects of a live oral E. coli vaccine on post-weaning diarrhea under on-farm conditions and to assess impacts of diet composition on growth and enteric health in the early nursery phase of production. Procedures and results: In a series of trials, even when enterotoxigenic E. coli (ETEC) was present, post-weaning diarrhea was usually associated with other causes and not ETEC. Therefore, an E. coli vaccination program had no benefit in either reducing clinical signs of diarrhea or in improving growth rate of pigs in the nursery. Conversely, under the same conditions, feeding programs affected both clinical signs of diarrhea and growth rate. Pigs fed a 4-phase program that transitioned from a diet containing a relatively high proportion of animal-based protein to a feed consisting of plant-based protein performed better than pigs receiving lower-complexity diets. However, there was evidence of compensatory growth in pigs fed low-complexity diets, albeit not consistently in all trials. Conclusion and clinical relevance: It was concluded that early nursery diet can help to reduce post-weaning diarrhea and improve growth performance.

Enquêtes sur les effets de la vaccination contreEscherichia coli et de la composition du régime alimentaire sur la diarrhée post-sevrage et les performances de croissance chez les porcs. Objectifs: Les porcs connaissent souvent une croissance lente et des problèmes de maladies entériques au début de la période post-sevrage. Les objectifs étaient d'évaluer les effets d'un vaccin oral vivant contre E. coli sur la diarrhée post-sevrage dans des conditions à la ferme et d'évaluer les impacts de la composition du régime alimentaire sur la croissance et la santé entérique au début de la phase de production en pouponnière. Procédures et résultats: Dans une série d'essais, même en présence d'E. coli entérotoxinogène (ETEC), la diarrhée post-sevrage était généralement associée à d'autres causes et non à l'ETEC. Par conséquent, un programme de vaccination contre E. coli n'a eu aucun effet bénéfique sur la réduction des signes cliniques de diarrhée ou sur l'amélioration du taux de croissance des porcs en pouponnière. Inversement, dans les mêmes conditions, les programmes d'alimentation ont affecté à la fois les signes cliniques de diarrhée et le taux de croissance. Les porcs nourris avec un programme en quatre phases qui sont passés d'un régime contenant une proportion relativement élevée de protéines animales à un aliment composé de protéines végétales ont obtenu de meilleurs résultats que les porcs recevant des régimes moins complexes. Cependant, il y avait des preuves d'une croissance compensatoire chez les porcs nourris avec des régimes à faible complexité, mais pas de manière constante dans tous les essais. Conclusion et pertinence clinique: Il a été conclu que l'alimentation précoce en pouponnière peut aider à réduire la diarrhée post-sevrage et à améliorer les performances de croissance.(Traduit par Dr Serge Messier).

Antibody responses to porcine reproductive and respiratory syndrome virus, influenza A virus, and Mycoplasma hyopneumoniae from weaning to the end of the finisher stage in fourteen groups of pigs in Ontario, Canada.

BACKGROUND: Respiratory diseases are among the most important factors affecting swine farm productivity in Canada. The objectives of this study were to investigate antibody responses to porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus (IAV), and Mycoplasma hyopneumoniae (M. hyopneumoniae) from weaning to the end of the finisher stage on a subset of commercial swine farms in Ontario, Canada, and to examine the association between nursery diet and antibody responses. RESULTS: Overall, older pigs were more likely to test seropositive for PRRSV and less likely to test seropositive for M. hyopneumoniae (p <  0.001). Pigs were more likely to test seropositive for IAV at weaning and the end of the grower and finisher stages compared to the end of nursery (p <  0.001). Pigs that were seropositive for IAV were more likely to test seropositive for both PRRSV and M. hyopneumoniae (p <  0.001). Two, 9, and 4 groups that had more than 20% of pigs seropositive to PRRSV, IAV, and M. hyopneumoniae, respectively, from the end of nursery to the end of finisher were classified as seropositive. Pigs fed a plant-based (low complexity) diet during nursery were more likely to be seropositive for PRRSV (p <  0.001) but there were no significant differences in seropositivity to IAV or M. hyopneumoniae due to nursery diet complexity. CONCLUSIONS: This study provides information regarding changes in serum antibody in pigs across different stages of production and highlights periods of vulnerability. Additionally, these findings may encourage further research into the effects of nursery diet complexity on disease susceptibility and immune response.

Identification of single-nucleotide variants associated with susceptibility to Salmonella in pigs using a genome-wide association approach.

BACKGROUND: Salmonella enterica serovars are a major cause of foodborne illness and have a substantial impact on global human health. In Canada, Salmonella is commonly found on swine farms and the increasing concern about drug use and antimicrobial resistance associated with Salmonella has promoted research into alternative control methods, including selecting for pig genotypes associated with resistance to Salmonella. The objective of this study was to identify single-nucleotide variants in the pig genome associated with Salmonella susceptibility using a genome-wide association approach. Repeated blood and fecal samples were collected from 809 pigs in 14 groups on farms and tonsils and lymph nodes were collected at slaughter. Sera were analyzed for Salmonella IgG antibodies by ELISA and feces and tissues were cultured for Salmonella. Pig DNA was genotyped using a custom 54 K single-nucleotide variant oligo array and logistic mixed-models used to identify SNVs associated with IgG seropositivity, shedding, and tissue colonization. RESULTS: Variants in/near PTPRJ (p = 0.0000066), ST6GALNAC3 (p = 0.0000099), and DCDC2C (n = 3, p < 0.0000086) were associated with susceptibility to Salmonella, while variants near AKAP12 (n = 3, p < 0.0000358) and in RALGAPA2 (p = 0.0000760) may be associated with susceptibility. CONCLUSIONS: Further study of the variants and genes identified may improve our understanding of neutrophil recruitment, intracellular killing of bacteria, and/or susceptibility to Salmonella and may help future efforts to reduce Salmonella on-farm through genetic approaches.

The relationship between hemoglobin levels at weaning and growth performance and antibody response in nursery pigs.

The objectives of this study were to determine whether weaned pigs with low hemoglobin (Hb) concentrations grow more slowly and produce poorer antibody response to vaccination compared to pigs with normal Hb concentrations, and to study the association between high levels of zinc oxide in feed and continued anemia in pigs during the nursery phase. At weaning, pigs were classified as anemic (< 90 g/L of Hb), iron deficient (90 to 110 g/L Hb), or normal (> 110 g/L Hb). Pigs were vaccinated twice against Mycoplasma hyopneumoniae and antibody response was measured 3 weeks after the last vaccination. Two trials were performed with diets containing 150 mg/kg of zinc oxide and a third trial was conducted with pigs fed a diet containing 3000 mg/kg of zinc oxide for 2 weeks post-weaning. Hemoglobin status didn't impact growth rate or antibody response to vaccination. High zinc levels in the feed did not alter the pattern of Hb concentrations in pigs post-weaning.

Relation entre les niveaux d'hémoglobine au sevrage et les performances de croissance et la réponse en anticorps chez des porcs en pouponnière. Les objectifs de la présente étude étaient de déterminer si les porcs sevrés avec de faibles concentrations en hémoglobine (Hb) avaient une croissance plus lente et produisaient moins d'anticorps en réponse à une vaccination comparativement à des porcs avec une concentration normale de Hb, et d'étudier l'association entre des niveaux élevés d'oxyde de zinc dans la moulée et une anémie continue chez les porcs durant la période en pouponnière. Au sevrage les porcs furent classés comme anémiques (< 90 g/L de Hb), déficients en fer (90 à 110 g/L de Hb) ou normaux (> 110 g/L de Hb). Les porcs furent vaccinés deux fois contre Mycoplasma hyopneumoniae et la réponse en anticorps mesurée 3 semaines après la dernière vaccination. Deux essais ont été effectués avec des diètes contenant 150 mg/kg d'oxyde de zinc et un troisième essai mené avec des porcs nourris avec une diète contenant 3000 mg/kg d'oxyde de zinc pendant 2 semaines après le sevrage. Le statu en hémoglobine n'avait pas d'impact sur le taux de croissance ou la réponse en anticorps à la suite de la vaccination. Des niveaux élevés de zinc dans la moulée n'ont pas altéré le patron des concentrations de Hb chez les porcs en post-sevrage.(Traduit par Dr Serge Messier).

Antibody Responses to Salmonella in Pigs from Weaning Up to Marketing and Presence of Salmonella at Slaughter.

Salmonella is estimated to be one of the leading causes of enteric illness worldwide. Human salmonellosis is most frequently related to contaminated food products, particularly those of animal origin, such as pork. Pigs are often asymptomatic carriers of Salmonella, highlighting the importance of identifying high-prevalence farms and effective detection methods. The objectives of this study were to investigate Salmonella antibody responses and their association with on-farm shedding and Salmonella isolation at slaughter. Fourteen groups of pigs from eight farrowing sources were followed from birth to slaughter (totaling 796 pigs). Information about farm management was collected through a questionnaire. Blood and fecal samples were collected four times at different stages of production, and palatine tonsils/submandibular lymph nodes were obtained at slaughter. Sera were tested for Salmonella antibodies by enzyme-linked immunosorbent assay, and fecal/tissue samples were cultured for Salmonella. Data were analyzed using a mixed-effect multivariable modeling method with farm, litter, and pig as random effects. Salmonella seropositivity rates were 20.3%, 5.8%, 15.9%, and 37.3% at weaning, at the end of nursery, at end of grower, and at end of finisher, respectively. Salmonella seropositivity and shedding increased with age (p < 0.05), and pigs shedding Salmonella were more likely to test seropositive (p = 0.02). Antibody response and shedding on-farm had no significant association with isolation of Salmonella from tissues harvested at slaughter. The variation in Salmonella seropositivity due to farm was 28.9% of total variation. These findings indicate that on-farm intervention may be a more effective approach to control Salmonella and to reduce the presence of Salmonella at slaughter. Additionally, the observation that some pigs in this study were Salmonella-negative throughout production and at slaughter is promising with regard to food safety, and studies are needed to explore the genotypes of those pigs.

Field studies evaluating the direct, indirect, total, and overall efficacy of Streptococcus suis autogenous vaccine in nursery pigs.

Vaccine effectiveness (VE) was evaluated on a farrow-to-finish farm experiencing mortality due to Streptococcus suis. Direct, indirect, total, and overall vaccine effectiveness were analyzed by vaccinating only 75% of pigs in each litter. Cox's regression and logistic regression revealed total and overall VE to be 27% and 21%, respectively.

Études sur le terrain évaluant l'efficacité directe, indirecte, totale et globale du vaccin autogène pour Streptococcus suis chez les porcelets sevrés. L'efficacité vaccinale (EV) a été évaluée dans une ferme de naissage-engraissage aux prises avec des mortalités causées par Streptococcus suis. L'efficacité vaccinale directe, indirecte, totale et globale ont été analysées en vaccinant seulement 75 % des porcs dans chaque portée. La régression de Cox et la régression logistique ont révélé que l'EV totale et l'EV globale étaient de 27 % et 21 %, respectivement.(Traduit par Isabelle Vallières).

Antimicrobial resistance of Streptococcus suis isolates recovered from clinically ill nursery pigs and from healthy pigs at different stages of production.

Streptococcus suis isolates (N = 379) from clinically ill pigs and from healthy pigs were tested for antimicrobial susceptibility using a disk diffusion method. Isolates from clinical cases had a higher prevalence of resistance compared with isolates from healthy pigs. There was a high to moderate prevalence of resistance to antibiotics commonly used in nursery pig diets such as tetracycline (84.2%), tiamulin (65.2%), and spectinomycin (40.4%). There was a low prevalence of resistance, however, to antimicrobials that are only used as parenteral treatments and not added to feed (e.g., ceftiofur, florfenicol). These findings should help practitioners in choosing appropriate drugs for use on Ontario swine farms.

Résistance antimicrobienne des isolats de Streptococcus suis récupérés de porcs en santé à différents stades de production et de porcelets de pouponnière cliniquement malades. Des isolats de Streptococcus suis (N = 379) provenant de porcs cliniquement malades et de porcs en santé ont été testés pour la susceptibilité antimicrobienne en utilisant une méthode de diffusion par disque. Les isolats des cas cliniques avaient une prévalence accrue de résistance comparativement aux isolats de porcs en santé. Il y avait une prévalence élevée à modérée de résistance aux antibiotiques communément utilisés dans les diètes des porcelets de pouponnière, dont la tétracycline (84,2 %), la tiamuline (65,2 %) et la spectinomycine (40,4 %). Par contre, il y avait une faible prévalence de la résistance aux antimicrobiens qui étaient seulement utilisés comme traitements parentéraux et non ajoutés aux aliments (p. ex., ceftiofur, florfénicol). Ces constatations devraient aider les praticiens à choisir les médicaments appropriés pour utilisation dans les fermes porcines de l'Ontario.(Traduit par Isabelle Vallières).

A clinical trial investigating the impact of in-feed flavophospholipol on Salmonella shedding and antimicrobial resistance in pigs.

A clinical trial was conducted to assess the effectiveness of in-feed flavophospholipol in reducing Salmonella shedding and antimicrobial resistance (AMR) associated with Salmonella and generic Escherichia coli in naturally infected grower-finisher pigs. Pigs were obtained from a farm with a history of salmonellosis and were housed at a research facility. Over the span of 10 weeks the pigs received either a feed containing 4 ppm of flavophospholipol (treatment, n = 25) or a non-medicated feed (control, n = 20). Weekly fecal samples were collected and cultured for Salmonella and generic E. coli. A subset of Salmonella and E. coli isolates were tested for antimicrobial susceptibility. A multilevel mixed-effects logistic regression model was used to compare the prevalence of Salmonella shedding and AMR in Salmonella and E. coli isolates in treatment and control groups. Overall, the prevalence of Salmonella shedding (P > 0.05) and AMR in Salmonella (P > 0.01) and E. coli (P > 0.005) isolates was not different between the treatment and control groups.

Essai clinique étudiant l'impact du flavophospholipol dans les aliments sur l'excrétion de Salmonellaet l'antibiorésistance chez les porcs. Un essai clinique a été réalisé pour évaluer l'efficacité du flavophospholipol dans les aliments pour réduire l'excrétion de Salmonella et l'antibiorésistance associée à Salmonella et à Escherichia coli générique chez les porcs d'engraissement naturellement infectés. Les porcs obtenus provenaient d'une ferme ayant des antécédents de salmonellose et ils ont été logés à un établissement de recherche. Pendant 10 semaines, les porcs ont reçu soit des aliments contenant 4 ppm de flavophospholipol (traitement, n = 25) ou des aliments non médicamentés (témoin, n = 20). Des échantillons fécaux hebdomadaires ont été prélevés et soumis à des cultures pour Salmonella et E. coli générique. Un sous-groupe d'isolats de Salmonella et d'E. coli ont été testés pour la susceptibilité antimicrobienne. Un modèle de régression logistique à effets contrastés à plusieurs niveaux a été utilisé pour comparer la prévalence d'excrétion de Salmonella et de l'antibiorésistance dans les isolats de Salmonella et d'E. coli dans le groupe de traitement et le groupe témoin. Dans l'ensemble, la prévalence d'excrétion de Salmonella (P > 0,05) et de l'antibiorésistance des isolats de Salmonella (P > 0,01) et d'E. coli (P > 0,005) n'était pas différente entre le groupe de traitement et le groupe témoin.(Traduit par Isabelle Vallières).

Factors contributing to mortality during a Streptoccocus suis outbreak in nursery pigs.

The objective of this study was to investigate the association between sow- and litter-level factors with mortality in a swine nursery barn experiencing a severe Streptococcus suis disease outbreak. All-cause mortality data from a 300-sow farrow-to-finish herd was analyzed using a Cox's regression model. The data were recorded over 6 months and included 24 cohorts, 297 sows, 295 litters, and 2779 piglets with an average of 14.4% post-weaning mortality. If the sows had 2 litters within the study period and pigs from their first litter experienced mortality, then pigs from their subsequent litter had a decreased risk of mortality [hazard ratio (HR) = 0.34, P < 0.05]. Pigs were more likely to experience mortality if at least 1 additional littermate experienced mortality (HR = 9.22, P = 0.001). Under conditions of this study, the results suggest mechanisms related to sow immunity and within-litter spread that could have contributed to the risk of mortality during the S. suis outbreak.

Facteurs contribuant à la mortalité durant une éclosion de Streptoccocus suis chez des porcelets en pouponnière. Cette étude avait pour objectif de faire enquête sur l'association entre les facteurs au niveau de la truie et de la portée en lien avec la mortalité dans une pouponnière de porcelets aux prises avec une grave éclosion de maladie causée par Streptococcus suis. Les données sur toutes les causes de mortalité provenant d'un troupeau de 300 truies de naissage-finition ont été analysées en utilisant un modèle de régression de Cox. Les données ont été enregistrées pendant 6 mois et incluaient 24 cohortes, 297 truies, 295 portées et 2779 porcelets avec une moyenne de mortalité après le sevrage de 14,4 %. Si les truies avaient 2 portées durant la période de l'étude et qu'il y avait de la mortalité chez les porcs de leur première portée, alors les porcs de leur portée subséquente présentaient un risque réduit de mortalité (taux de risque [TR] = 0,34, P < 0,05). Il était plus probable qu'il y ait de la mortalité chez les porcs si au moins 1 autre compagnon de portée était mort (TR = 9,22, P = 0,001). En vertu des conditions de cette étude, les résultats suggèrent des mécanismes associés à l'immunité des truies et à l'écart au sein de la portée qui ont pu contribuer au risque de mortalité durant l'éclosion de S. suis.(Traduit par Isabelle Vallières).

An epidemiological study of Streptococcus suis serotypes of pigs in Ontario determined by a multiplex polymerase chain reaction.

The purpose of the study was to identify the serotypes of Streptococcus suis from tonsil swabs in clinically ill and healthy pigs in Ontario using a multiplex polymerase chain reaction (PCR) method. Although 22 different serotypes were identified, most isolates were S. suis-like bacteria or untypable.

Étude épidémiologique des sérotypes Streptococcus suisdes porcs en Ontario déterminés par amplification en chaîne par polymérase multiplexe. Le but de cette étude consistait à identifier les sérotypes de Streptococcus suis provenant d'écouvillons des amygdales chez des porcs cliniquement malades et en santé en Ontario en utilisant une méthode multiplexe d'amplification en chaîne par polymérase (PCR). Même si 22 sérotypes différents ont été identifiés, la plupart des isolats étaient des bactéries de type S. suis ou non typables.(Traduit par Isabelle Vallières).

Reduction of Salmonella enterica serovar typhimurium DT104 infection in experimentally challenged weaned pigs fed a lactobacillus-fermented feed.

Salmonella Typhimurium is a foodborne pathogen and commonly present on pig farms. Probiotics have shown potential as a means of reducing Salmonella shedding in pigs. Three experimental challenge trials were conducted to investigate the potential application of newly isolated Lactobacillus isolates for controlling Salmonella infection in pigs. In each trial, 16 Yorkshire piglets (28-d old) were randomly allocated to 1 of 4 dietary treatments: (1) basal diet (BD), (2) naturally fermented (NF) feed, (3) Lactobacillus zeae-fermented (LZ-F) feed, and 4) Lactobacillus casei-fermented (LC-F) feed. All pigs consumed their assigned diets for 3 d prior to the challenge of Salmonella Typhimurium DT104 (approximately 6 log colony-forming units/pig) through gavage. Pediococcus pentosaceus, L. zeae, and L. casei were most abundant in NF, LZ-F, and LC-F feed, respectively. After the challenge, pigs on fermented feed had lower rectal temperature, diarrhea scores, serum haptoglobin concentrations, and intestinal Salmonella counts than the control group (BD) (p ≤ 0.01). Salmonella spp. were detected in both ileocecal lymph nodes (ICLN) and spleens from all pigs on BD, NF, and LC-F, but only 50% of spleens from pigs on LZ-F. Pigs had a dynamic spatial and temporal immune response to Salmonella infection and dietary treatments, as indicated by up- and downregulation in gene expression of inflammatory cytokines (interleukin (IL)-1ß, IL-6, IL-10, interferon-γ, and tumor necrosis factor) in the ileum, ICLN, and spleen. The alternation in cytokine expression by fermented feed, particularly LZ-F, appeared to benefit pigs in combating Salmonella infection.

An epidemiological investigation into the association between biomarkers and growth performance in nursery pigs.

BACKGROUND: Biomarkers are useful tools in research and clinical practice where they are often used to detect and monitor differences in the physiological state of an animal. The proteins IGF-1, IGFBP-3, GHR, CRP, SAA, Hp, IFN-α, IFN-γ, TNF-α, IL-1ß, IL-6, IL-10, and IL-18 have been proposed as potential biomarkers for monitoring growth in livestock. The objective of this study was to determine whether hepatic gene expression of these proposed biomarkers is associated with growth performance in nursery pigs. Herd information and growth parameters were collected for 168 piglets from 8 commercial farms in southern Ontario. From these pigs, a subset of liver tissue samples (n = 74) was used for gene expression analysis of the proposed biomarkers. Multivariable linear regression methods were used to determine whether genetic expression of the proposed biomarkers was associated with growth performance in the nursery. RESULTS: Modelling the herd information and individual piglet traits in relation to growth performance revealed that the weight at weaning and the age at weaning are significantly associated with nursery performance. Average daily gain (ADG) was significantly associated with hepatic IGFBP-3 and GHR expression in the liver (P < 0.05), and tended to be associated with hepatic IGF-1 expression (P = 0.071). Similarly, 9-week body weight was significantly associated with hepatic expression of IGFBP-3 and GHR expression (P < 0.05), and tended to be associated with hepatic expression of IGF-1 (P = 0.055). CONCLUSION: The age and weight at which pigs are weaned is an important determinant for nursery performance. Hepatic gene expression of IGF-1, IGFBP-3, and GHR can be useful biomarkers for monitoring growth performance in nursery pigs.

How do swine practitioners and veterinary pathologists arrive at a diagnosis of Clostridium perfringens type A enteritis in neonatal piglets?

A questionnaire was administered to 22 veterinary practitioners and 17 veterinary pathologists to investigate the methods used for diagnosis of Clostridium perfringens type A enteritis in neonatal pigs. Practitioners generally diagnosed C. perfringens type A associated enteritis by age of onset of diarrhea (between 1 to 7 days of age). Most practitioners (95%) were moderately to very confident in their diagnosis. Pathologists generally diagnosed C. perfringens type A associated enteritis by combinations of isolation of the organism, genotyping or detecting the toxins of the organism, and ruling out other pathogens through histopathology. Almost half (41%) of the pathologists were not confident of their diagnosis. This study reports that the current diagnostic method for C. perfringens type A enteritis is not specific, and although many pathologists expressed reservations about making a diagnosis of C. perfringens type A enteritis, most practitioners were confident in their diagnosis, even though reported clinical signs of clostridial diarrhea are similar to those of a number of other enteric diseases.

Comment les praticiens porcins et les pathologistes vétérinaires parviennent-ils à un diagnostic d'entérite àClostridium perfringenstype A chez les porcelets nouveau-nés? Un questionnaire a été administré à 22 praticiens vétérinaires et à 17 pathologistes vétérinaires afin de faire enquête sur les méthodes utilisées pour le diagnostic de l'entérite à Clostridium perfringens type A chez les porcs nouveau-nés. Les praticiens diagnostiquaient généralement une entérite associée à C. perfringens type A selon l'âge à l'apparition de la diarrhée (âge d'entre 1 et 7 jours). La plupart des praticiens (95 %) ont déclaré un niveau de confiance de modérément confiant à très confiant à l'égard de leur diagnostic. Les pathologistes diagnostiquaient généralement l'entérite associée à C. perfringens type A par une combinaison d'isolement de l'organisme, du génotypage ou de la détection des toxines de l'organisme et éliminaient les autres agents pathogènes à l'aide d'une histopathologie. Près de la moitié (41 %) des pathologistes n'étaient pas confiants de leur diagnostic. Cette étude signale que la méthode diagnostique actuelle pour l'entérite à C. perfringens type A n'est pas spécifique et, même si beaucoup de pathologistes ont exprimé des réserves à propos d'un diagnostic d'entérite à C. perfringens type A, la plupart des praticiens éprouvaient de la confiance face à leur diagnostic, même si les signes cliniques signalés de la diarrhée clostridiale sont semblables à plusieurs autres maladies entériques.(Traduit par Isabelle Vallières).

The epidemiology of Clostridium perfringens type A on Ontario swine farms, with special reference to cpb2-positive isolates.

BACKGROUND: There is poor understanding of most aspects of Clostridium perfringens type A as a possible cause of neonatal diarrhea in piglets, and the prevalence and types of C. perfringens present on Ontario swine farms is unknown. To study the prevalence of fecal C. perfringens and selected toxin genes, 48 Ontario swine farms were visited between August 2010 and May 2011, and 354 fecal samples were collected from suckling pigs, lactating sows, weanling pigs, grower-finisher pigs, and gestating sows, as well as from manure pits. The fecal samples were cultured quantitatively, and toxin genes were detected by real-time multiplex polymerase chain reaction (PCR). RESULTS: In mixed multivariable linear analysis, log(10) C. perfringens in fecal samples from suckling pigs were higher than that of weanling pigs, grower-finisher pigs, and manure pit samples (P <0.05). In mixed multivariable logistic analysis, the C. perfringens isolates recovered from lactating sows (OR = 0.069, P <0.001), gestating sows (OR = 0.020, P <0.001), grower-finishers (OR = 0.017, P <0.001), and manure pits (OR = 0.11, P <0.001) were less likely to be positive for the consensus beta2 toxin gene cpb2 compared to the isolates from suckling pigs. The prevalence of cpb2 in the isolates recovered from weanlings did not differ significantly from suckling pigs. C. perfringens isolates that were positive for cpb2 were more likely to carry the atypical cpb2 gene (atyp-cpb2) (OR = 19, P <0.001) compared to isolates that were negative for cpb2. Multivariable analysis did not identify farm factors affecting the presence of consensus cpb2 and atyp-cpb2 genes. CONCLUSIONS: This study provides baseline data on the prevalence of C. perfringens and associated toxin genes in healthy pigs at different stages of production on Ontario swine farms. The study suggests that if C. perfringens type A are involved in neonatal enteritis, there may be strains with specific characteristics that cannot be identified by the existing genotyping system.

Compositional analysis of the tonsil microbiota in relationship to Streptococcus suis disease in nursery pigs in Ontario.

BACKGROUND: The tonsil of the soft palate in pigs is the colonization site of both commensal and pathogenic microbial agents. Streptococcus suis infections are a significant economic problem in the swine industry. The development of S. suis disease remains poorly understood. The purpose of this study was to identify whether the tonsillar microbiota profile in nursery pigs is altered with S. suis disease. Here, the dynamics of the tonsillar microbiota from 20 healthy pigs and 43 diseased pigs with S. suis clinical signs was characterized. RESULTS: Based on the presence or absence of S. suis in the systemic sites, diseased pigs were classified into confirmed (n = 20) or probable (n = 23) group, respectively. Microbiota composition was assessed using the V3-V4 hypervariable region of the 16S rRNA, and results were analyzed to identify the diversity of the tonsillar microbiota. The taxonomic composition of the tonsil microbiota proved to be highly diverse between individuals, and the results showed statistically significant microbial community structure among the diagnosis groups. The confirmed group had the lowest observed species richness while the probable group had higher phylogenetics diversity level compared to the healthy group. Un-weighted Unifrac also demonstrated that the probable group had a higher beta diversity than both the healthy and the confirmed group. A Dirichlet-multinomial mixture (DMM) model-based clustering method partitioned the tonsil microbiota into two distinct community types that did not correspond with disease status. However, there was an association between Streptococcus suis serotype 2 and DMM community type 1 (p = 0.03). ANCOM-BC identified 24 Streptococcus amplicon sequence variants (ASVs) that were differentially abundant between the DMM community types. CONCLUSIONS: This study provides a comprehensive analysis of the structure and membership of the tonsil microbiota in nursery pigs and uncovers differences and similarities across varying S. suis disease status. While the overall abundance of Streptococcus was not different among the diagnosis groups, the unique profile of DMM community type 1 and the observed correlation with S. suis serotype 2 could provide insight into potential tonsillar microbiota involvement in S. suis disease.

Detection and characterization of Giardia duodenalis and Cryptosporidium spp. on swine farms in Ontario, Canada.

As part of the C-EnterNet surveillance program of the Public Health Agency of Canada, 122 pooled swine manure samples from 10 farms in Ontario, Canada were collected and tested for Giardia and Cryptosporidium. Giardia duodenalis cysts and Cryptosporidium spp. oocysts were detected using immunofluorescence microscopy. Nested-polymerase chain reaction protocols were performed to amplify the small subunit rRNA gene and the ß-giardin gene for G. duodenalis, and the small subunit rRNA gene and the heat shock protein-70 gene for Cryptosporidium spp. The DNA amplicons were sequenced to determine genotypes and species. A mixed multivariable method was used to compare the presence of Giardia and Cryptosporidium in different stages of production. Both Giardia cysts and Cryptosporidium oocysts were present on all tested farms, with 50.8% of the samples positive for G. duodenalis and 44.3% positive for Cryptosporidium spp. by microscopy, and 66.4% and 55.7%, respectively, positive by polymerase chain reaction (PCR). No significant agreement was observed between microscopy and PCR method to detect Giardia and Cryptosporidium (p<0.05). The prevalence of Giardia in manure pits and finisher pigs did not differ (p>0.05), however, it was less frequent (odds ratio, OR=0.21 [0.07, 0.63]) among sows. Cryptosporidium was more likely (OR=3.6 [1.3, 9.9]) to be detected in manure pits and weaners (OR=3.3 [1.1, 10.0]) compared to finisher pigs, and it was less frequent (OR=0.06 [0.007, 0.55]) in sows than in finishers (p<0.05). DNA sequencing demonstrated that 92.1% of the Giardia isolates were Assemblage B and 7.9% were Assemblage E. The most prevalent Cryptosporidium were Cryptosporidium parvum (55.4%), and Cryptosporidium sp. pig genotype II (37.5%). These findings indicate that the occurrence of zoonotic isolates of G. duodenalis and Cryptosporidium is very high on swine farms in southern Ontario, and that there is a potential for transmission between swine and humans by means of cyst and oocyst contaminated water or foods.

Serotypes, Virulence-Associated Factors, and Antimicrobial Resistance of Streptococcus suis Isolates Recovered From Sick and Healthy Pigs Determined by Whole-Genome Sequencing.

Streptococcus suis is ubiquitous in swine, and yet, only a small percentage of pigs become clinically ill. The objective of this study was to describe the distribution of serotypes, virulence-associated factor (VAF), and antimicrobial resistance (AMR) genes in S. suis isolates recovered from systemic (blood, meninges, spleen, and lymph node) and non-systemic (tonsil, nasal cavities, ileum, and rectum) sites of sick and healthy pigs using whole-genome sequencing. In total, 273 S. suis isolates recovered from 112 pigs (47 isolates from systemic and 136 from non-systemic sites of 65 sick pigs; 90 isolates from non-systemic sites of 47 healthy pigs) on 17 Ontario farms were subjected to whole-genome sequencing. Using in silico typing, 21 serotypes were identified with serotypes 9 (13.9%) and 2 (8.4%) as the most frequent serotypes, whereas 53 (19.4%) isolates remained untypable. The relative frequency of VAF genes in isolates from systemic (Kruskal-Wallis, p < 0.001) and non-systemic (Kruskal-Wallis, p < 0.001) sites in sick pigs was higher compared with isolates from non-systemic sites in healthy pigs. Although many VAF genes were abundant in all isolates, three genes, including dltA [Fisher's test (FT), p < 0.001], luxS (FT, p = 0.01), and troA (FT, p = 0.02), were more prevalent in isolates recovered from systemic sites compared with non-systemic sites of pigs. Among the isolates, 98% had at least one AMR gene, and 79% had genes associated with at least four drug classes. The most frequently detected AMR genes were tetO conferring resistance to tetracycline and ermB conferring resistance to macrolide, lincosamide, and streptogramin. The wide distribution of VAFs genes in S. suis isolates in this study suggests that other host and environmental factors may contribute to S. suis disease development.

Study of the relationship between untypable and typable isolates of Streptococcus suis recovered from clinically ill and healthy nursery pigs.

Streptococcus suis naturally colonizes the upper respiratory tract of pigs and can lead to severe disease conditions. Although there are several serotypes associated with disease, untypable isolates have also been observed. The objective of this study was to investigate the relatedness of untypable S. suis isolates detected in clinical cases and healthy pigs in Ontario, Canada, and their relation to typing serotypes. One hundred fifty-six isolates obtained from 33 cases and 26 farm-and-pen-matched control pigs were sequenced using Illumina HiSeq sequencing. Protein sequences of the capsular polysaccharide genes (cps) were identified and analyzed using a maximum likelihood tree. Among the 27 untypable isolates, 3 were from systemic sites of cases and 13 and 11 were from upper respiratory sites of cases and controls, respectively. One hundred fifty-six isolates were grouped into 17 distinct groups based on the cps gene tree. Isolates from these 17 distinct individual cps groups were distributed among a minimum of one farm and maximum of eight farms. Untypable isolates were detected in 12 of those groups and each cps group had untypable isolates present amongst multiple farms. Interestingly, the three systemic untypable isolates not only coexisted with other serotypes found in the same location of the same pigs but were also found among different cps groups. These isolates are of interest and warrant further investigation. Overall, a wide diversity of S. suis among untypable isolates was observed in this study.