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).

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.

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.

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.

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).

Identifying Active Salmonella Infections in Swine Nurseries Using Serology and Bacterial Culture and Evaluating Associated Risk Factors.

The objectives of this study were: to identify nursery cohorts with an active Salmonella infection using combined serological and bacteriological methods, and to try to identify risk factors associated with swine nurseries with active Salmonella spread. Twenty pigs from each of 50 cohorts of weaned pigs from 44 different nursery barns were sampled about the time of weaning and near the end of the nursery stage. Information regarding farm management and biosecurity practices were collected using a questionnaire. Blood samples were obtained at both visits, while rectal swabs were collected at the second visit. An enzyme-linked immunosorbent assay (ELISA) was used to test sera for Salmonella antibodies and rectal samples were cultured for Salmonella. A nursery cohort was identified as having an active Salmonella infection if Salmonella was cultured from one or more of the 20 pigs or if serological evidence suggested exposure to Salmonella. The association between farm-level management covariates and active Salmonella infection was assessed in 46 cohorts using a logistic regression model. Nine of 46 (20%) cohorts produced Salmonella-free pigs. The remaining 37 (80%) cohorts were classified as having an active infection. Examination of risk factors failed to identify how negative and positive nurseries differed.

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.

Effect of flavophospholipol on fecal microbiota in weaned pigs challenged with Salmonella Typhimurium.

BACKGROUND: The heightened prevalence of Salmonella Typhimurium remains a public health and food safety concern. Studies have reported antibiotic, flavophospholipol, may have the ability to reduce Salmonella in swine, as well as alter the gut microbiota in favour of beneficial bacteria by inhibiting pathogenic bacteria. Thus, the objective of this study was to investigate the fecal microbiota of weaned pigs receiving in-feed flavophospholipol and challenged with Salmonella Typhimurium. RESULTS: Twenty-one weaned pigs were fed either a diet containing 4 ppm of flavophospholipol (treatment group) or a non-medicated feed (control group) for 36 days post-weaning (Day 1 to Day 36). The pigs were orally challenged with a 2 mL dose of 108 CFU/mL of S. Typhimurium at Day 7 and Day 8. Community bacterial DNA extracted from fecal samples collected at Day 6 (before challenge) and Day 36 (28 days after challenge) were used to assess the fecal microbiota using the V4 region of the 16S rRNA gene with Illumina MiSeq next-generation sequencing. Sequencing data were visualized using mothur and analyzed in JMP and R software. The fecal microbiota of pigs in the treatment group had differences in abundance of phyla (Firmicutes, Proteobacteria) and genera (Lactobacillus, Roseburia, Treponema, unclassified Ruminococcaceae, Blautia, Streptococcus, Megasphaera, Dorea, Sporobacter, Peptococcus, unclassified Firmicutes, Clostridium IV and Campylobacter) when compared to pigs that were controls, 28 days after challenge with Salmonella (P < 0.05). Specifically, results demonstrated a significant increase in phylum Proteobacteria (P = 0.001) and decrease in Firmicutes (P = 0.012) and genus Roseburia (P = 0.003) in the treated pigs suggestive of possible microbial dysbiosis. An increased abundance of genera Lactobacillus (P = 0.012) was also noted in the treated group in comparison to the control. CONCLUSION: Based on these findings, it is difficult to conclude whether treatment with 4 ppm of flavophospholipol is promoting favorable indigenous bacteria in the pig microbiota as previous literature has suggested.

A Case-Control Study to Investigate the Serotypes of S. suis Isolates by Multiplex PCR in Nursery Pigs in Ontario, Canada.

: Streptococcus suis naturally inhabits the tonsils and nasal cavities of pigs. Some strains can cause systemic infection, leading to a wide range of diseases. A case-control study was conducted to (i) examine serotypes isolated from systemic sites (blood/meninges/spleen) in cases, (ii) determine whether serotypes in systemic sites were found in upper respiratory sites (tonsil/nasal cavity) of the same cases, and (iii) determine the serotypes in upper respiratory sites of case and farm and pen- matched controls. In total, 606 samples from 128 pigs were cultured for S. suis. The isolates were examined for presence of gdh and recN genes by polymerase chain reaction (PCR) and were identified as S. suis if both genes were present. The S. suis isolates were then serotyped using a two step-multiplex PCR. Serotypes 9 (n = 9), (2,1/2) (n = 7) and untypable isolates (n = 7) were most commonly found in systemic sites. Detection of serotypes 9 (p = 0.03) in upper respiratory sites were positively associated with their detection in systemic sites of cases, while a trend was seen with serotype (2,1/2) (p = 0.07). Last, no association between serotypes recovered from upper respiratory sites of cases and controls could be detected. Untypable isolates were detected in high frequency, which warrants further investigation. This study confirms that a variety of serotypes can be found in commercial swine production and shows a difference in serotypes recovered from systemic sites in pigs with clinical signs of S. suis infections.

Effect of nursery feeding program on serum haptoglobin, growth performance, and carcass characteristics of pigs reared on commercial farms.

A total of 774 pigs were enrolled in 13 cohorts across 7 commercial farms to examine the effect of nursery feeding program on serum haptoglobin, subsequent growth performance, and carcass characteristics of finishing pigs. Pigs were weaned [23.4 ± 0.2 days of age and 5.3 ± 1.5 kg body weight (BW)] and randomly assigned to either a complex (HC: highly digestible sources of proteins, including animal proteins; N = 346) or simple (LC: corn- and soybean meal-based; N = 340) diet for 37.7 ± 1.7 days over 3 phases (1 pen per diet per cohort; pen was the experimental unit; n = 13); sex was balanced between treatments. Thereafter, pigs received common grower-finisher diets. At a targeted BW of 118 kg, pigs (subset: n = 275 and 258 for HC and LC, respectively) were processed to evaluate carcass characteristics. Nursery feeding program did not influence BW, BW gain, or serum haptoglobin at any stage of production. Feed cost was reduced by $2.82 per pig during the nursery period for the LC-fed pigs (P < 0.001). Loin eye depth, back fat depth, carcass weight, percent lean yield, and carcass gross revenue at slaughter were not influenced by nursery feeding program. Feeding LC nursery diets on commercial farms is a feasible way to reduce feed cost without negatively impacting serum haptoglobin, growth performance during or after the nursery period, or carcass value.

Un total de 774 porcs fut inclus dans 13 cohortes sur sept fermes commerciales afin d'examiner l'effet d'un programme d'alimentation en pouponnière sur l'haptoglobine sérique, les performances de croissance subséquentes, et les caractéristiques des carcasses des porcs en finition. Les porcs furent sevrés [23,4 ± 0,2 jours d'âge et 5,3 ± 1,5 kg de poids corporel (BW)] et assignés au hasard à une diète complexe (HC : source de protéines hautement digestibles, incluant des protéines animales; N = 346) ou une diète simple (LC : moulée à base de maïs et de soya; N = 340) pendant 37,7 ± 1,7 jours sur trois phases (1 parc par diète par cohorte; le parc était l'unité expérimentale; n = 13); les sexes étaient équilibrés entre les traitements. Par la suite, les porcs recevaient une diète de croissance-finition commune. Au poids cible de 118 kg, les porcs (sous-groupe : n = 275 et 258 pour HC et LC, respectivement) étaient abattus pour évaluer les caractéristiques des carcasses. Le programme alimentaire en pouponnière n'a pas influencé le BW, le gain de BW, ou l'haptoglobine sérique à aucun stade de production. Le coût en aliment fut réduit de 2,82 $ par porc durant la période en pouponnière pour les porcs LC (P < 0,001). La profondeur de l'oeil de la longe, l'épaisseur du gras dorsal, le poids de la carcasse, le pourcentage de rendement maigre, et le revenu brut par carcasse à l'abattage n'étaient pas influencés par le programme alimentaire en pouponnière. Nourrir avec une diète LC en pouponnière sur des fermes commerciales est un moyen réaliste de réduire les coûts en aliment sans affecter négativement l'haptoglobine sérique, les performances de croissance durant et après la période en pouponnière, ou la valeur des carcasses.(Traduit par Docteur Serge Messier).

Salmonella shedding and seropositivity and its association with in-feed flavophospholipol in nursery pigs.

The objective of this study was to assess the impact of in-feed flavophospholipol on Salmonella shedding and antibody response in nursery pigs. Weaned pigs were fed either a diet containing 4 ppm flavophospholipol (n = 16) or a non-medicated feed (n = 16) for 36 d. All pigs were orally challenged with a 2-mL dose of 108 colony-forming units (CFUs)/mL of Salmonella Typhimurium on Days 7 and 8 of the trial. On Day 36, all pigs were euthanized and samples were collected from the liver, spleen, and ileocecal lymph nodes. Fecal and tissue samples were quantitatively cultured for Salmonella and serum samples were tested for the presence of the Salmonella antibody by enzyme-linked immunosorbent assay (ELISA). There was no difference between the 2 groups in antibody response and the presence of Salmonella in feces and tissue (P > 0.05). Medicating nursery diets with flavophospholipol at 4 ppm did not appear to reduce Salmonella infection in nursery pigs.

L'objectif de la présente étude était d'évaluer l'impact de l'ajout de flavophospholipol dans l'aliment sur l'excrétion de Salmonella et la réponse en anticorps chez des porcs en pouponnière. Des porcs sevrés ont été nourris avec soit une diète contenant 4 ppm de flavophospholipol (n = 16) ou une diète non-médicamentée (n = 16) pendant 36 j. Tous les porcs ont reçu oralement une dose de 2 mL de 108 unités formatrices de colonies (UFC)/mL de Salmonella Typhimurium aux Jours 7 et 8 de l'essai. Au Jour 36, tous les porcs ont été euthanasiés et on préleva des échantillons de foie, rate, et noeuds lymphatiques iléo-caecaux. Des échantillons de fèces et de tissus ont été cultivés pour quantifier le nombre de Salmonella et des échantillons de sérum furent testés pour la présence d'anticorps contre Salmonella par épreuve immunoenzymatique (ELISA). Il n'y avait pas de différence entre les deux groupes quant à la réponse en anticorps et la présence de Salmonella dans les fèces et les tissus (P > 0,05). L'ajout de 4 ppm de flavophospholipol à la diète en pouponnière ne semble pas réduire l'infection par Salmonella chez les porcs en pouponnière.(Traduit par Docteur Serge Messier).

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).

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).

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.

Salmonella fecal shedding in pigs from birth to market and its association with the presence of Salmonella in palatine tonsils and submandibular lymph nodes at slaughter.

Salmonella is an important cause of foodborne illnesses in humans. Food-producing animals, including swine, are a major source of Salmonella in food products. This study investigated on farm Salmonella fecal shedding in pigs at different production stages - from weaning to marketing - and its association with the presence of Salmonella in tissues at slaughter. Fourteen groups from 8 commercial farrowing sources (N = 809 pigs) were monitored 5 times from birth to slaughter. Fecal and tissue samples were collected from pigs and cultured for Salmonella. A survey was conducted to collect farm management information. A multi-level mixed-effects logistic regression modelling method was used to analyze Salmonella shedding over time and the association between Salmonella shedding and the presence of Salmonella in tissue samples. Salmonella was recovered from 13% (421/3339) of fecal samples collected from 809 pigs over the course of the study. Overall, 35% (284) of pigs shed Salmonella at least once, while 12% (99) shed more than once. Salmonella shedding increased as pigs aged (P = 0.01) and increased in the summer months (P < 0.01). Salmonella was isolated from tissue samples collected from 23% (134/580) of pigs; however, the presence of Salmonella at slaughter was not associated with on farm shedding. The seasonal trend in Salmonella shedding and its association with age may be used to identify high-risk groups and implement more effective control measures accordingly. The identification of repeat shedders warrants interventions that target this source of infection on swine farms.

Salmonella est une cause importante de maladies d'origine alimentaire chez les humains. Les animaux de rente, incluant le porc, sont une source majeure de Salmonella dans les produits alimentaires. Au cours de la présente étude nous avons examiné l'excrétion fécale de Salmonella à la ferme à différents stades de la production ­ du sevrage jusqu'à la mise en marché ­ et sont association avec la présence de Salmonella dans les tissus au moment de l'abattage. Quatorze groupes provenant de huit sources commerciales de mise-bas (N = 809 porcs) ont été surveillés cinq fois entre la naissance et l'abattage. Des échantillons de fèces et de tissus ont été prélevés des porcs et cultivés pour Salmonella. Un sondage a été mené pour amasser des informations sur la gestion de la ferme. Une méthode de modélisation de régression logistique à effets mixtes de niveaux multiples a été utilisée pour analyser l'excrétion de Salmonella dans le temps et l'association entre l'excrétion de Salmonella et la présence de Salmonella dans les échantillons de tissus. Salmonella a été isolé de 13 % (421/3339) des échantillons de fèces prélevés des 809 porcs durant la durée de cette étude. Au total, 35 % (284) des porcs ont excrété Salmonella au moins une fois, alors que 12 % (99) ont excrété plus d'une fois. L'excrétion de Salmonella augmentait à mesure que les porcs vieillissaient (P = 0,01) et augmentait durant les mois d'été (P < 0,01). Salmonella a été isolé d'échantillons de tissu prélevés de 23 % (134/580) des porcs; toutefois, la présence de Salmonella au moment de l'abattage n'était pas associée avec l'excrétion à la ferme. La tendance saisonnière dans l'excrétion de Salmonella et son association avec l'âge pourraient être utilisées afin d'identifier les groupes à risque élevé et mettre en place selon le cas des méthodes de maitrise plus efficaces. L'identification d'excréteurs à répétition justifie des interventions qui ciblent cette source d'infection sur les fermes porcines.(Traduit par Docteur Serge Messier).

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).

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).