Management factors associated with perinatal lamb mortality in Prince Edward Island flocks.

The objective of this observational cohort study was to identify management factors associated with lamb mortality risk for sheep flocks in Prince Edward Island, Canada. Data were collected from 50 lambing groups from 36 sheep flocks during 3 farm visits before, during and after the lambing seasons in 2014-15. Variables of interest included flock management practices, ewe health indicators, ewe nutrition, litter size and lamb birth weight. Principal component analysis was performed and resulting component scores were used for further analysis using a mixed Poisson regression model with lamb mortality risk as the outcome. The median group-level lamb mortality in the first 8 weeks of life was 10.0 % (0 %-30.3 %), with 25 groups having lamb mortality greater than 10 %, which is considered higher than the standard productivity goal. Four principal component scores were retained in the final model identifying generalized factors associated with lamb mortality: 1) flock factors, 2) forage factors, 3) lamb health factors, and 4) general health factors. Specifically, the following management factors were indirectly through the 4 principal components associated with lower lamb mortality: using goal setting; having a strong working relationship with a veterinarian; seeking veterinary advice for animal treatment; using benzimidazole-class anthelmintics; feeding forage with high crude protein, digestible energy, and net energy for maintenance and low acid detergent fiber to late-gestation ewes; applying visual lamb identification methods; using anti-coccidial prophylactic medication to lambs; administering clostridial vaccines to lambs; avoiding separation of hypothermic lambs from their dams; and treatment/prevention of neurological and/or wasting disease. Although this study is exploratory, and confirmation is required, the results should help sheep farmers and researchers direct attention to management variables that could reduce lamb mortality in sheep flocks.

Identification, tissue characterization, and innate immune role of Angiogenin-4 expression in young broiler chickens.

Intestinal epithelial cells are major producers of antimicrobial proteins, which play an important role in innate immunity. In addition to defensins, the Ribonuclease A superfamily includes important antimicrobial proteins involved in host-defense mechanisms in vertebrates. Angiogenin-4 (Ang4), a member of this RNase superfamily, has been demonstrated to be secreted by Paneth cells in mice. We have successfully cloned and characterized a new chicken gene (chAng4), found for the first time in a nonmammalian species, from intestinal epithelial and lymphoid cells. Characterization of chAng4 revealed 99% nucleotide and 97% amino acid sequence homology to mouse Ang4. Similar functional regions were identified, suggesting a role in innate immunity and regulation of gut microbiota. Furthermore, the mRNA expression pattern of chAng4 was studied in broilers in the presence or absence of beneficial bacteria (probiotics) and organic acids. The results showed that one-day-old chickens expressed low levels of Ang4 in almost all the evaluated tissues (crop, proventriculus, duodenum, jejunum, ileum, and cecal tonsils), except in the bursa of Fabricius that presented the highest expression level. The addition of probiotics and organic acids for either 7 or 14 consecutive days demonstrated a direct effect of probiotics and organic acids on chAng4 expression; moreover, broilers receiving probiotics and organic acids for only 7 D showed higher levels of chAng4 expression compared with those treated for 14 D. Broilers without treatment had a constant high level of expression in cecal tonsils and bursa. In conclusion, we were able to identify and characterize a new antimicrobial gene in chickens (chAng4) throughout the gastrointestinal tract. chAng4 mRNA gene expression was associated with the presence of naturally occurring and supplemented (probiotic) bacteria. The encoded protein might have a potential bactericidal effect against intestinal nonpathogenic and pathogenic microbes, modulating the intestinal microbiota and the innate immunity, and thereby may help minimize the use of antibiotics in poultry feed.

The Cattle Microbiota and the Immune System: An Evolving Field.

New insights into the host-microbiota relationship have recently emerged with the advancement of molecular technologies such as next-generation sequencing. This article presents the current knowledge regarding the interaction between bacteria and the immune system of the gut, the uterus, and the mammary gland of cattle.

Potential group B Streptococcus interspecies transmission between cattle and people in Colombian dairy farms.

Group B Streptococcus (GBS), is a leading cause of neonatal death and an emerging pathogen in adults. Additionally, GBS is a bovine pathogen causing intramammary infections. The likelihood of GBS interspecies transmission is largely unknown. We explored the potential transmission of GBS between cattle and people on dairy farms in Colombia and compared the antimicrobial resistance (AMR) profiles of isolates from both host species. Across 33 farms, throat swabs and rectal swabs were collected from 191 people, and rectal swabs and composite milk samples from 2092 cattle, yielding 60 human isolates and 301 bovine isolates. The majority (64%) of isolates belonged to shared sequence types (ST). Sequence type (ST) 1 was the most common strain in both host species, suggesting that interspecies transmission may be possible. Two members of the bovine-specific clonal complex 61/67 were detected in human samples (ST718 and ST1175), providing evidence for the lack of genuine species barriers. Apparent prevalence of penicillin resistance was surprisingly high in human and bovine isolates. Further investigation of this phenomenon is needed and could lead to modification of standard testing and treatment recommendations in human and veterinary medicine.

Molecular variability of Streptococcus uberis isolates from intramammary infections in Canadian dairy farms from the Maritime region.

The primary objective of this study was to explore the variability of Streptococcus uberis (S. uberis) isolates by extracting multilocus sequence typing (MLST) data from whole-genome sequencing. The secondary objective was to determine the distribution of the phenotypic antimicrobial resistance (AMR) and the associated AMR genes as well as the virulence gene profiles among sequence types (STs). Sixty-two isolates were recovered from 16 herds in 3 Canadian Maritime Provinces: New Brunswick (14.5%), Nova Scotia (48.3%), and Prince Edward Island (37.1%). Of these, 9, 30, and 23 were recovered from post-calving, lactational samples, and post-mastitis samples, respectively. These 62 S. uberis isolates belonged to 34 STs; 11 isolates were typed to 9 known STs and 51 isolates were classified as one of 25 new STs. Thirteen isolates were part of major clonal complexes (CCs). Post-mastitis isolates contained 10 unique STs, lactational isolates contained 11 unique STs, and post-calving isolates had 3 STs. Each farm had only 1 isolate that was a unique ST except for STs 233, 851, 855, 857, 864, and 866, which were found in multiple cows per herd on more than one farm. ST851 and ST857 were found in each of the 3 sample types, with ST857 found in cows from all 3 Maritime provinces. These results indicate that S. uberis is a diverse non-clonal pathogen with specific STs residing in clonal clusters, carrying multiple AMR genes and virulence, with a diverse phenotypic AMR.

L'objectif premier de la présente étude était d'explorer la variabilité d'isolats de Streptococcus uberis en extrayant les données de typage génomique multilocus (MLST) du séquençage du génome entier. L'objectif secondaire était de déterminer la distribution des phénotypes de résistance antimicrobienne (AMR) et les gènes d'AMR associés ainsi que les profils des gènes de virulence parmi les types de séquence (STs). Soixante-deux isolats ont été obtenus de 16 troupeaux dans trois provinces maritimes canadiennes : le Nouveau-Brunswick (14,5 %), la Nouvelle-Écosse (48,3 %), et l'Ile-du Prince-Édouard (37,1 %). Parmi ces isolats, 9, 30, et 23 ont été obtenus d'échantillons post-vêlage, en lactation, et post-mammite, respectivement. Ces 62 échantillons appartenaient à 34 STs; 11 isolats ont été typés comme appartenant à 9 STs connus et 51 isolats ont été classifiés dans un des 25 nouveaux STs. Treize isolats faisaient partis de complexes clonaux majeurs (CCs). Les isolats post-mammite contenaient 10 STs uniques, les isolats de la période de lactation contenaient 11 STs uniques, et ceux de la période post-vêlage avaient 3 STs. Chaque ferme n'avait seulement qu'un isolat qui avait un ST unique sauf pour les STs 233, 851, 855, 857, 864, et 866 qui ont été retrouvés chez plusieurs vaches par troupeau sur plus d'une ferme. Les ST851 et ST857 ont été trouvés dans chacun des trois types d'échantillons, avec ST857 retrouvé dans des vaches des trois provinces maritimes. Ces résultats indiquent que S. uberis est un agent pathogène diversifié non-clonal avec des STs spécifiques résidant dans des groupements clonaux, arborant de multiples gènes de résistance antimicrobienne et de virulence, avec des phénotypes d'AMR variés.(Traduit par Docteur Serge Messier).

Detection of endotoxin in plasma of hospitalized diarrheic calves.

OBJECTIVES: To investigate whether lipopolysaccharide (LPS) is present in plasma of calves with naturally occurring diarrhea. The second objective was to determine whether plasma [LPS] correlates with clinical, hematological, biochemical, and acid-base variables, and whether [LPS] differs between surviving and nonsurviving diarrheic calves. DESIGN: Prospective observational study (January 2012-May 2014). SETTING: Veterinary teaching hospital. ANIMALS: Thirty-four calves <28 days old admitted for diagnosis and treatment of diarrhea and 30 healthy control calves. MEASUREMENTS AND MAIN RESULTS: Admission demographics, physical examination, blood gas, biochemistry analysis, and outcome data were recorded. Plasma concentration of LPS was determined using a bovine LPS ELISA assay. Plasma [LPS] was detected in both healthy and diarrheic calves. Plasma [LPS] was significantly higher in diarrheic than healthy calves (median: 0.99 ng/mL; Interquartile range (IQR): 0.068, vs 0.88 ng/mL; 0.065 ng/mL, respectively; P < 0.001). Plasma [LPS] was higher in nonsurviving (1.04 ng/mL; 0.07 ng/mL) than in surviving calves (0.98 ng/mL; 0.022 ng/mL; P < 0.001). Plasma [LPS] was higher in beef (1.07 ng/mL; 0.182 ng/mL) than in dairy diarrheic calves (0.99 ng/mL; 0.022 ng/mL; P < 0.001). In diarrheic calves, plasma [LPS] correlated with [l-lactate] (r2 = 0.496; P = 0.002); hypoglycemia (r2 = -0.453; P = 0.007); increased unmeasured strong ions (r2 = 0.332; P = 0.050), [Mg2+ ] (r2 = 0.475; P = 0.004), and [phosphate] (r2 = 0.468; P = 0.005), and increased aspartate aminotransferase activity (r2 = 0.348; P = 0.003). CONCLUSIONS: This study highlights a potential role of LPS in the pathogenesis of metabolic derangements such as hyperlactatemia, hypoglycemia, and increased concentration of unmeasured strong anions in diarrheic calves. Further investigation evaluating the effect of LPS on l-lactate and glucose metabolism in diarrheic calves is warranted.

Evaluation of the Precision Xtra meter for monitoring blood ß-hydroxybutyrate concentrations in late-gestation ewes.

Blood samples were collected from late-gestation ewes to determine the agreement of a point-of-care (POC) Precision Xtra meter and a standard laboratory test for ß-hydroxybutyrate (BHBA). Fresh whole blood samples were immediately tested with the POC instrument, and serum samples were analyzed with a standard commercial biochemical analyzer. Ewes were classified as having ketonemia if their BHBA concentrations were ≥800 µmol/L. Scatter plots, paired t-tests, Bland-Altman limits of agreement, and Gwet AC1 tests were used to compare results. The 2 tests had very good agreement. The values between instruments were not statistically different based on paired t-tests ( p = 0.312). The intercept and slope of a linear mixed model, containing the standard test results as an outcome and the POC meter results as a predictor, were 0.02 (95% CI: 0.00, 0.04) and 0.98 (95% CI: 0.96, 1.01), respectively. When the samples were classified into ketonemic classes (non-ketonemic and ketonemic) based on BHBA concentrations obtained from each test, the Gwet AC1 statistic was 0.94 (95% CI: 0.91, 0.97; p < 0.001). The ketosis classification agreed in 95% of samples. Based on the Bland-Altman plot and limits of agreement, the optimal cutoff to diagnose ketonemia with the POC meter was 1,000 µmol/L, which is 200 µmol/L higher than the laboratory BHBA medical decision limit. The Precision Xtra meter provided excellent correlation and substantial agreement with the standard laboratory technique for measuring blood BHBA in late-gestation ewes.

Streptococcus agalactiae is not always an obligate intramammary pathogen: Molecular epidemiology of GBS from milk, feces and environment in Colombian dairy herds.

For many years Streptococcus agalactiae has been considered an obligate intramammary and strictly contagious pathogen in dairy cattle. However, recent reports of S. agalactiae isolation from extramammary sources have contradicted that premise. To gain further insight into the epidemiology of S. agalactiae infection in cattle, we examined its distribution and heterogeneity of strains in bovine milk, bovine feces, and the environment in Colombian dairy farms. First, a longitudinal study was conducted at herd level in 152 dairy herds. Bulk tank milk samples from each herd where collected twice a month for six months. A follow-up study with a cross sectional design at the cow level was conducted in a subset of 25 farms positive for S. agalactiae. Cow-level milk samples from 1712 lactatting cows and 1545 rectal samples were collected, as well as 120 environmental samples. Samples were used for S. agalactiae detection and genotyping using Multi Locus Sequence Typing. Results showed sporadic rather than repeated isolation of S. agalactiae from bulk tank milk in 40% of the positive herds, challenging the idea that S. agalactiae is a highly contagious pathogen causing chronic infections. S. agalactiae was isolated from rectal or environmental samples in 32% and 12% of cross-sectional study farms, respectively, demonstrating that the bacteria can survive in extramammary sources and that S. agalactiae is not an obligate intramammary pathogen. The same strain was isolated from rectal and bulk tank milk samples in eight farms, suggesting that fecal shedding is frequent, and contributes to the presence of S. agalactiae in bulk tank. High within-herd heterogeneity of strains was found, which is distinct from the situation in developed dairy industries. These new epidemiological findings should be considered to adjust surveillance and control recommendations for S. agalactiae.

The association of serum ß-hydroxybutyrate concentration with fetal number and health indicators in late-gestation ewes in commercial meat flocks in Prince Edward Island.

Late-gestation ewes are susceptible to ketonemia resulting from high energy requirement for fetal growth during the last few weeks of pregnancy. High lamb mortality is a possible consequence of effects of ketonemia on both ewes and lambs. Determining risk factors to ketonemia is a fundamental step to identify ewes at risk, in order to avoid losses caused by ketonemia. Serum ß-hydroxybutyrate (BHBA) concentrations of 384 late-gestation ewe samples were determined. Physical examinations, including body condition, FAMACHA© and hygiene scoring, were performed. Udders and teeth were also examined. Fecal floatation was performed to detect gastrointestinal helminth eggs of the ewe fecal samples. General feeding management practices and season at sampling were recorded. Litter sizes were retrieved from lambing records. Factors associated with log serum BHBA concentration were determined using a linear mixed model, with flock and lambing groups as random effects. The mean serum BHBA concentration was 545.8 (±453.3) µmol/l. Ewes with a body condition score (BCS) of 2.5-3.5 had significantly lower log BHBA concentrations than ewes with a BCS of ≤2.0, by 19.7% (p = 0.035). Ewes with a BCS of >3.5 had a trend toward higher log BHBA concentrations compared to ewes with a BCS of 2.5-3.5. Ewes with a FAMACHA© score of 3 had significantly higher log BHBA concentrations than ewes with a FAMACHA© score of 1 or 2, by 12.1% (p = 0.049). Ewes in which gastrointestinal helminth eggs were detected had significantly higher log BHBA concentrations than ewes in which helminth eggs were not detected, by 12.3% (p = 0.040). An increased litter size was associated with higher log BHBA concentration (p ≤ 0.003), with the log BHBA concentrations of ewes having twins, triplets, and quadruplets or quintuplets were higher than those of ewes having singleton by 19.2%, 30.4%, and 85.2%, respectively. Season at sampling confounded the association between log BHBA concentration and FAMACHA© score, and therefore was retained in the final model even though it was not statistically significant. Intra-class correlation coefficients at the flock and lambing group levels were 0.14 and 0.32, respectively.

Short-term effect of supplemental yeast extract without or with feed enzymes on growth performance, immune status and gut structure of weaned pigs challenged with Escherichia coli lipopolysaccharide.

BACKGROUND: This study investigated the response of piglets receiving a yeast extract without or with a multi-enzyme mixture compared with an antimicrobial growth promoter (AGP) on performance, immune status and gut structure after an E. coli lipopolysaccharide (LPS) challenge. Thirty-six pigs were allotted to six treatments including: a non-challenged control (NCC); LPS-challenged control (CC); CC + AGP; CC + yeast extract; CC + enzymes; and CC + enzymes + yeast extract. On d 7, pigs were bled and thereafter injected with LPS or sterile saline. Blood samples were collected at 6, 48, and 96 h post-challenge. After 96 h post-challenge, pigs were euthanized to obtain duodenal, jejunal and ileal samples. RESULTS: Overall (d 1 to 11), compared with CC pigs, AGP attenuated the LPS-induced reduction in ADG (P = 0.004), ADFI (P = 0.03) and gain/feed ratio (P = 0.01). At 6 h post-challenge, AGP pigs had lower plasma urea N (PUN; P = 0.02) and serum TNF- α concentration (P = 0.07), and higher platelet count (P = 0.04) and serum IL-10 concentration (P = 0.02) than CC pigs. At 48 h post-challenge, AGP pigs had lower PUN (P = 0.02) than CC pigs, whereas enzymes + yeast extract interacted non-additively (P = 0.001) to reduce PUN. At 96 h post-challenge, AGP pigs had lower PUN (P = 0.02) and higher duodenal (P = 0.03), jejunal (P = 0.01) and ileal (P = 0.07) villus height than CC pigs. In addition, enzymes + yeast extract interacted additively and non-additively to reduce ileal IFN-γ (P < 0.0001) and IL-10 (P = 0.012) expression, respectively. Generally, no differences (P > 0.10) were observed between AGP and enzymes + yeast extract pigs on other measured parameters except for the downregulation of ileal IFN-γ (P < 0.0001) and TNF-α (P = 0.003) in enzymes + yeast extract pigs at 96 h post-challenge. CONCLUSIONS: The LPS challenged piglets receiving enzymes + yeast extract showed beneficial responses in gut structure and immunity commensurate with those receiving antibiotics, though the latter had better overall growth performance.

Development of a duplex Fluorescent Microsphere Immunoassay (FMIA) for the detection of antibody responses to influenza A and newcastle disease viruses.

Highly pathogenic avian influenza virus (HPAI) and virulent forms of avian paramyxovirus-1 (APMV-1) cause serious illnesses in domestic poultry, both of which are reportable to the World Organization of Animal Health (OIE). The clinical presentation of avian influenza (AI) and APMV-1 infections are difficult to differentiate, emphasizing the importance of rapid and sensitive serologic assays that are able to distinguish them. Currently, a variety of serological assays are used for the serologic diagnosis of both diseases, but these assays are not used in multiplex formats. In this study, development of a duplex fluorescent microsphere immunoassay (FMIA) based on Luminex xMAP Technology is described. The assay employs MagPlex magnetic microspheres that are covalently coated with recombinant avian influenza virus nucleoprotein and APMV-1 nucleocapsid antigens produced in a baculovirus insect cell expression system. The assay is able to detect AIV antibodies against all existing hemagglutinin (H1-H16) subtypes and simultaneously detect antibodies against APMV-1. In the process of this assay development different bead coupling conditions were compared. The assay has the capability of detecting serum antibodies from chickens and turkeys and optimization was accomplished by using 2462 chicken and 446 turkey field and experimental sera and had a comparable detection capability with currently used assays in the laboratory. Assay threshold values were calculated with Receiver Operating Characteristic Analysis (ROC) in non-parametric analysis due to a highly skewed data distribution; this analysis resulted in AIV nucleoprotein relative diagnostic sensitivity and specificity of 99.7%, and 97.3% respectively. The APMV-1 nucleocapsid relative diagnostic sensitivity and specificity were 95.4%, and 98.5% respectively.

A study of the effectiveness of a needle-free injection device compared with a needle and syringe used to vaccinate calves against bovine viral diarrhea and infectious bovine rhinotracheitis viruses.

The aim of this study was to compare the effectiveness of a needle-free injection device (NF) with a needle and syringe (NS) when used to vaccinate calves against bovine viral diarrhea virus (BVDV) and infectious bovine rhinotracheitis virus (IBRV). The study was conducted in two independent phases. Ninety-six crossbred beef calves were vaccinated in the spring and 98 beef calves in the autumn. The calves were vaccinated using a NF or NS at 2 months of age (day 0) and again on day 119, with a modified-live virus vaccine containing IBRV, BVDV (types 1 and 2), parainfluenza-3 virus, and bovine respiratory syncytial virus. In each herd 10 calves were left unvaccinated to determine whether exposure to either BVDV or IBRV occurred. Visible vaccine residue at the surface of the skin/hair was apparent immediately following vaccination with NF in 30% of the spring-born calves following both the primary and booster vaccination. In the autumn, visible vaccine residues occurred in 19% and 8% of NF-vaccinated calves following the primary and booster vaccination. Post-vaccination skin reactions recorded on days 21, 42, 119 and 140 occurred with greater frequency in NF-vaccinated calves than NS-vaccinated ones. Blood samples were collected on days 0, 21, 42, 119, and 140 and tested for antibodies to BVDV and IBRV. Vaccination technique had no significant effect on BVDV or IBRV antibody concentrations at any time point. NF was as effective as NS vaccination in eliciting BVDV and IBRV antibody responses.

Toxinotyping of necrotic enteritis-producing and commensal isolates of Clostridium perfringens from chickens fed organic diets.

The present study determined the effect of Clostridium perfringens isolates taken from necrotic enteritis (NE) outbreaks on organic farms in a NE virulence testing model. Thirteen strains were isolated in the course of the study. Six C. perfringens field isolates were taken from a naturally occurring NE outbreak on an organic farm. Polymerase chain reaction toxinotyping was used to establish C. perfringens strains, as well as to create a toxin profile. All field isolates were found to be type A and positive for alpha, beta-2 and netB toxin genes. During the NE virulence model, digesta samples were collected before oral inoculation to define the C. perfringens found as part of the natural flora. Three of the five natural flora isolates were found to be C. perfringens type E while the other two isolates were type A; only four of five isolates were positive for either netB or beta-2 toxin genes. Two isolates collected after inoculation were C. perfringens type A positive for cpb2 and netB. All isolates were tested positive for the quorum-sensing-related gene luxS, regardless of the strain source. The presence of luxS, alpha, netB and beta-2 toxin genes seems not to be a determinant of the disease as they were present in isolates from both outbreak birds as well as healthy and pre-inoculated birds. The C. perfringens field isolates induced mild NE lesions in one-half of the birds during the challenge study. Other mechanisms must play a role in the development of the disease beyond toxinotype, potentially including intestinal ecology and health, which would account for acute disease as seen in the field outbreak.