Seroprevalence of Lawsonia intracellularis in different swine populations in 3 provinces in Canada

Development and validation of a flow cytometry antibody test for Lawsonia intracellularis

Lawsonia intracellularis is the etiologic agent of porcine proliferative enteropathy (PPE), an inflammatory bowel disease with a major economic impact on the pig industry. The serological diagnosis of PPE can be performed using Blocking or Indirect ELISA, Immunoperoxidase Monolayer Assay (IPMA) and Indirect Fluorescence Antibody Test (IFAT). Here, we designed a most sophisticated immunological method for the detection of porcine anti-L. intracellularis IgGs, named Flow Cytometry Antibody Test - FCAT. This assay uses whole, live-attenuated L. intracellularis bacteria derived from a commercial vaccine. For the assay, we set up the optimal antigen concentration (10⁶ bacterium/assay), primary antibody dilution (1:100), time of incubation (20 min), antigen stability (15 days), precision (coefficient of variation - CV < 10%), reproducibility (CV ≤ 13%) and Receiver Operating Characteristic (ROC). When using a cut-off of >15.15% for FCAT, we determined that it showed a sensitivity of 98.8% and specificity of 100%. The rate of agreement with IPMA was 84.09% with a kappa index of 0.66. FCAT was used to screen 1,000 sera from non-vaccinated pigs housed in 22 different farms and we found that 730 pigs (73%) from 16 farms (72.7%) had L. intracellularis IgG. This high prevalence confirms that L. intracellularis is endemic on Brazilian pig farms. Finally, we determined that FCAT is an easy to perform diagnostic assay and we would highly recommend it for: i) seroepidemiological studies; ii) evaluation of infection dynamics; and iii) characterization of the humoral response profile induced by vaccines.

Microbiota of vaccinated and non-vaccinated clinically inconspicuous and conspicuous piglets under natural Lawsonia intracellularis infection

Lawsonia (L.) intracellularis is a widespread, economically important bacterium causing the porcine proliferative enteropathy (PPE). In this study, we evaluated intestinal microbiota of naturally exposed L. intracellularis-positive pigs under standardized conditions. To obtain three independent repetitions, 27 L. intracellularis-infected pigs (19.0 ± 1.50 kg body weight) from one farm were divided into three groups at an age of 7 to 8 weeks (nine pigs/group). Pigs were either vaccinated against L. intracellularis via oral drenching on their 21st day of life (attenuated live vaccine) or non-vaccinated and selected according to clinical findings (pigs without deviating fecal consistency or with moderate to soft fecal consistency). Comparison of the clinically inconspicuous piglets that differed regarding their vaccination status showed fewer significant differences in fecal microbiota composition. The vaccination led to an overall enrichment of bacterial species belonging to the order Clostridiales, while species of the genus Collinsella and Prevotella were decreased. Several bacterial species belonging to the order Bacteroidales, mainly of the family Prevotellacecae, often closely matching Prevotella copri differed significantly between non-vaccinated clinically inconspicuous and conspicuous piglets. Whether those bacterial species play a role in mitigating the severity of an L. intracellularis infection remains to be defined.

Prevalence of Lawsonia intracellularis in pig herds in different European countries

Background

Lawsonia intracellularis causes large economic losses in the pig industry worldwide. Pigs suffer from reduced daily weight gain, poor feed conversion ratio and increased mortality. The number of affected animals and herds in Europe remains unknown. This study will provide an overview of the prevalence of Lawsonia intracellularis in herds with a history of diarrhoea in different European countries and thereby identify country specific differences.

Results

Out of the 144 herds sampled in Germany, Denmark, Spain, the Netherlands and the United Kingdom, 90.3% (79.2-100.0%) contained at least one positive faecal sample on quantitative polymerase chain reaction (qPCR). Of the 6450 nursery, growing and finishing pigs of the previously mentioned herds, 26.2% (15.9-41.5%) of the animals were tested positive in faecal samples. Enzyme linked immunosorbent assay (ELISA) results of 60 herds were 91.7% (70-100%) positive. The percentage of positive samples in these 1791 blood samples was 31.6% (20.3-51.0%). Herd prevalence did not differ significantly by qPCR or ELISA. Significant differences between the countries were found regarding: Within-herd prevalence- qPCR: Samples from Denmark were more often positive than samples of Spain or the United Kingdom. Within-herd prevalence- ELISA: Samples from Denmark were more often positive than samples from Spain and the Netherlands. Affected age category- qPCR: Nursery pigs in Denmark were more often positive and shed more genome equivalents than nursery pigs in the other countries. Concentration of detected genome equivalents- qPCR: The concentration of genome equivalents from Lawsonia intracellularis in herds in Denmark was higher compared to all other countries.

Conclusion

A widespread of Lawsonia intracellularis in the six European countries was confirmed, whereby a large part of the positive animals only excreted small amounts of genome equivalents. Country specific differences were found with Denmark in particular diagnosing more Lawsonia intracellularis then the other countries. Herd data collected in this study needs to be analysed to get more information about possible reasons for the differences found between the countries.

Serological profile, seroprevalence and risk factors related to Lawsonia intracellularis infection in swine herds from Minas Gerais State, Brazil

Background

Lawsonia intracellularis is the etiologic agent of proliferative enteropathy, which causes diarrhea in several animal species, including swine. Serology can be used both to determine the prevalence of antibodies against a specific pathogen in a herd and to obtain the serological profile, which is used to determine the dynamics of infection in the herd. The objective of this study was to determine the serological profile and seroprevalence of anti-L. intracellularis antibodies in swine herds from intensive production regions of Minas Gerais, Brazil, and to identify the risk factors related to the herd-level seropositivity.

Results

A total of 2999 serum samples were collected for this cross–sectional study in the four major regions of intensive swine production in Minas Gerais, Brazil. To obtain better estimates and increase the external validity of the seroprevalence, the sample data were weighted based on the pig population of each herd, the stratum in which the herd was classified and the swine population of the region where each herd was located. A questionnaire was used to identify potential risk factors related to this herd-level seropositivity. The overall weighted prevalence in Minas Gerais was 34.7 % (95 % confidence interval: 32.12 - 37.20 %), and there was no significant difference among the sampled regions, with the seroprevalence rates ranging between 32.06 and 37.66 %. Finishing pigs were the most prevalent among the sampled categories. Among the evaluated risk factors, “cleaning before disinfecting” had a negative impact in the seroprevalence (p < 0.05) and was considered a protective factor.

Conclusions

The anti-L. intracellularis antibodies were detected in all of the investigated herds in Minas Gerais, which indicated a wide distribution of the agent in the state. The predominant serological profile was consistent with the dynamics of infection previously observed in pig herds in other countries with similar antimicrobial usage, in which the nursery pigs usually show the lowest seroprevalence and the finishing pigs exhibit the highest. Herds that adopt the practice of “cleaning before disinfection” can decrease their L. intracellularis antibody seropositivity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0618-z) contains supplementary material, which is available to authorized users.

Disease risks associated with free-ranging wild boar in Saskatchewan

This study investigated the disease status of Saskatchewan's feral wild boar population. Whole carcasses, tissue samples, and/or serum from 81 hunter-killed boars from Saskatchewan were submitted to the Canadian Wildlife Health Cooperative (CWHC) between 2009 and 2014. Serological tests were negative for PRRS, H1N1, and H3N2 swine influenza, PCV-2, and TGE/PRCV in 22/22 boars and for Toxoplasma gondii and Mycoplasma hyopneumoniae in 20/20 boars. Of 20 boars whose sera were tested 20 were positive for Actinobacillus pleuropneumoniae, with 7 positive for, among other strains, serotype 14; 16 were positive for Lawsonia intracellularis, 1 was positive and 6 were suspicious for Salmonella spp. Polymerase chain reaction tests were negative for PRRS and PCV2 in 58/58 boars and positive for Torque teno virus in 1/8 boars. Digestion assays were negative for Trichinella spp. in 22/22 boars. The high seroprevalence of A. pleuropneumoniae serotype 14 is noteworthy as this serotype has not been previously reported in North America.

Exposure of feral swine (Sus scrofa) in the United States to selected pathogens

Feral swine (Sus scrofa) are widely distributed in the United States. In 2011 and 2012, serum samples and tonsils were recovered from 162 and 37 feral swine, respectively, in the US to evaluate exposure to important swine endemic pathogens. Antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) were found in 2.5% and 25.3% of tested sera, respectively. Positive serological reactions against Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae have been detected in 19.7% and 69.7% of animals. More than 15% of animals presented antibodies against these 2 pathogens simultaneously. Most animals were also seropositive for Lawsonia intracellularis. Feral swine can also be involved in transmission of zoonotic agents. Almost 50% of animals possessed antibodies against Salmonella. In addition, 94.4% of animals were carriers of Streptococcus suis in their tonsils. In conclusion, feral swine may be considered as a potential reservoir for different endemic diseases in domestic pigs, as well as for important zoonotic agents.

Effects of feeding 10% rapeseed meal (Brassica napus) during gestation and lactation over three reproductive cycles on the performance of hyperprolific sows and their litters

Quiniou, N., Quinsac, A., Crépon, K., Evrard, J., Peyronnet, C., Bourdillon, A., Royer, E. and Etienne, M. 2012. Effects of feeding 10% rapeseed meal (Brassica napus) during gestation and lactation over three reproductive cycles on the performance of hyperprolific sows and their litters. Can. J. Anim. Sci. 92: 513–524. Largely due to increased production of biodiesel, there is a greater availability of solvent-extracted rapeseed meal (RM) in France, making it competitive for feeding pigs. Nevertheless, the long-term effects of dietary glucosinolates (GSL) when feeding RM on sow reproductive and litter performance are a persistent concern to feed manufacturers. Four batches of 24 hyperprolific sows were fed to evaluate the effects of including 0 or 10% RM [14.5 µmol GLS g−1dry matter (DM) basis] in the gestation and lactation diets over three reproductive cycles. Intake of dietary GLS remained below 5 mmol d−1over the gestation period and averaged 8 mmol d−1over the lactation period, corresponding to less than 2 µmol GLS g−1DM basis. Lactation feed intake, sow body weight and backfat, and the length of the weaning-to-estrus interval were not different (P>0.05) between treatment groups. Sows fed diets with 10% or no RM farrowed 43.6 and 43.8 piglets over three reproductive cycles, respectively (P>0.05). Piglet weight at birth or weaning, survival and litter weight gain were not affected (P>0.05) by dietary RM inclusion. Similar (P>0.10) plasma thyroxin levels of sows and piglets indicated that thyroid function was not altered by RM inclusion. In conclusion, feeding gestation and lactation diets including 10% RM to hyper prolific sows over three parities was safe and did not affect sow longevity, reproductive or litter performance.

The comparative roles of polyunsaturated fatty acids in pig neonatal development

The present review focuses on the importance of polyunsaturated fatty acid (PUFA) provision for the normal development of the pig neonate. The review describes first the selected fatty acid composition of a range of porcine tissues including nervous tissues, muscle and adipose tissues, reproductive organs and immune-responsive organs and/or cells. The importance of PUFA to the functioning of the immune system of the neonate is considered briefly and is followed by an in-depth consideration of the sources of PUFA for the neonatal pig. The effects of different categories or specific types of fatty acid (i.e. non-essential, linoleic, α-linolenic, long-chain n-6 and n-3 PUFA) on various indices of pig neonatal growth are reviewed. The importance of n-3 PUFA supply to the fetal and early neonatal pig is underlined and evidence is presented for more attention to be given to the amounts available from maternal sources. Based on the material reviewed, recommendations are made on the dietary intake of PUFA in the gestating pig.

Rapeseed glucosinolates and iodine in sows affect the milk iodine concentration and the iodine status of piglets

I in the chain sow diet --> blood serum of sow --> sow milk --> piglet serum was investigated in two experiments with a total of eighty-one sows and their piglets. In experiments conducted during the last trimester of gravidity and the 28 d of lactation, diets with glucosinolates (1.9 mmol/kg diet via 100 g ground rapeseed/kg diet (Expt 1) and 2.1 and 4.2 mmol/kg diet via 75 and 150 g rapeseed press cake/kg diet (Expt 2)) were compared with control groups without rapeseed products. From 0 to 600 microg I/kg was added to sow diets during lactation. Diets without supplementary I decreased the I concentration particularly in milk and piglet serum. The presence of rapeseed and rapeseed press cake were indicated by a thiocyanate concentration increase, mainly in sow serum. The diets with glucosinolates decreased the milk and piglet serum I concentration. Spot urine and faeces samples from sows eating the rapeseed-press cake diets had increased I concentration. The sows' serum I and thyroxine did not respond to glucosinolates (Expt 1) or these diets caused an increase in concentration (Expt 2). Both these criteria seem unsuitable for the diagnosis of I status of adult animals. Glucosinolates and their degradation compounds may affect the thyroid and the mammary glands resulting in lower I milk transfer and higher renal and intestinal I excretion.

Effect of rapeseed feedstuffs with different glucosinolate content and iodine administration on gestating and lactating sow

In two experiments with a total of 60 sows during late pregnancy and at 28 days of lactation, diets containing rapeseed were compared with rapeseed free diets (control). In Experiment 1 dietary content of solvent extracted rapeseed meal was 250 g/kg (10 mmol glucosinolates/kg diet), in Experiment 2 diets containing 100 g/kg rapeseed were tested (2 mmol glucosinolates/kg diet). During late pregnancy all sows received 150 micrograms supplementary iodine/kg diet. In lactation, different subgroups received different rates of iodine administration (Exp. 1:0, 100 or 1000 micrograms/kg diet; Exp. 2: 0, 150 or 300 micrograms/kg diet). Rapeseed feeds had no significant effect on feed intake, body weight of sows and rearing parameters in both experiments. There was a tendency (8%) toward lower litter weight at weaning in Exp. 1. Sow diets without supplementary iodine but containing glucosinolates (via rapeseed meal, rapeseed) caused significant reduction in thyroxine serum concentration of piglets, whereas this hormone did not change in sow serum. Thiocyanate was significantly increased in the serum of mothers. The minor increase of thiocyanate concentration of milk and piglets' serum points to negligible transfer of rapeseed glucosinolate degradation products to offspring. However, the milk iodine concentration was significantly decreased due to glucosinolates, and this seems to be the reason for impaired iodine and thyroid hormone status of piglets from sows given rapeseed feeds.

Rapeseed meal-glucosinolates and their antinutritional effects. Part 5. Animal reproduction

Although there is no clear evidence to fully describe the mechanism involved in glucosinolate-related effects on animal reproduction, lowered fertility in animals fed diets with rapeseed meal (RSM) inclusion is related to glucosinolate content in the diet. Negative effects can result both from multidirectional action of glucosinolates, malnutrition of mother due to the thyroid dysfunction, transfer of goitrogenic compounds to foetus and reduced transfer of nutritive compounds (e.g. iodine) through the placenta. The degree of reproduction impairment depends both on glucosinolate content and on the type of animal. Pregnant female rats are sensitive to the presence of glucosinolates, and the first symptoms of fertility impairment and lowering of offspring survival rate may occur at low glucosinolate levels, e.g. with diets containing low glucosinolate rapeseed meal (LG-RSM). In the case of swine, the limiting value above which sows fertility may be impaired is 4 mumol of total glucosinolates per g diet and 8 mmol of daily intake of these compounds. Opinions on the permitted RSM inclusion in diet for hens are very divergent. Some authors recommend limiting of the RSM inclusion to 10%, while others did not find any lowering of egg production in hens fed with two- or three-fold greater RSM inclusion rates. Most long-term experiments with heifers, cows and ewes indicate that ruminants tolerate the level of glucosinolate in LG-RSM although feeding this fodder as the only high-protein concentrate component may lead to impaired fertility.

Rapeseed: constituents and protein products. Part 3. Nutritional value of protein-enriched products

The review concerns the nutritional properties of protein preparations from Brassica seed with different species of animals. Special consideration is taken on the one side to the effect of feeding varieties with high and low glucosinolate content, on the other hand to the influence of technological treatment of this products.

RAPESEED MEAL AS A REPLACEMENT FOR SOYBEAN MEAL IN DIETS OF PROGENY FROM SOWS FED EITHER PROTEIN SUPPLEMENT

First- and second-litter progeny from sows fed either 0 or 8% solvent-extracted rapeseed meal in replacement for isonitrogenous amounts of soybean meal and wheat was used to evaluate solvent-extracted rapeseed meal as a protein source. There was no influence of the dam’s diet on gain, efficiency of feed utilization, digestible (DE) and metabolizable energy (ME) or digestible nitrogen (DN) and nitrogen retention in the progeny. In pigs from first litters, the feeding of 8% rapeseed meal, compared with 0% rapeseed meal, depressed feed intake and rate of gain in the finishing period from 55 to 90 kg liveweight, and resulted in reduced gain and poorer efficiency of feed utilization for the overall experiment from 6 kg initial weight. Carcasses from rapeseed meal-fed pigs were leaner. Gilt carcasses were leaner than barrow carcasses. With second-litter pigs, there were no significant differences associated with dietary treatment or sex. There were no significant differences in DE or ME or in DN and nitrogen retention between pigs receiving 0 or 8% rapeseed meal in either the starting diets at 6 weeks of age or the growing diets at 40 kg liveweight.