Porcine ear necrosis is associated with social behaviours in weaned piglets.

BACKGROUND: Porcine ear necrosis (PEN) is a worldwide health issue and its aetiology is still unclear. The aim of this study was to describe the prevalence and the severity of PEN in a commercial farm, associated with pig behaviour and health biomarkers measures. On two consecutive batches, PEN prevalence was determined at the pen level. PEN scores, blood haptoglobin concentration and oxidative status were measured on two pigs per pen (n = 48 pens) 9, 30 and 50 days (D) after arrival to the post-weaning unit. Social nosing, oral manipulation and aggression of pen mates and exploration of enrichment materials were observed on two to three pigs per pen twice a week from D9 to D50. RESULTS: At the pen level, the higher the time spent nosing pen mates, the lower the percentage of pigs affected by PEN during both the early and the late post-weaning periods (P < 0.002) and, in the opposite, the higher the time spent orally manipulating pen mates during the late post-weaning period, the higher the percentage of affected pigs (P = 0.03). At the pig level, the higher the increase in hydroperoxides and haptoglobin during the early post-weaning period, the higher the PEN scores on D30 (P < 0.001). CONCLUSIONS: This study suggests that a high incidence of social nosing, which can be an indicator of good social cohesion in a group, was significantly associated with less frequent lesions of PEN. In opposite, high incidence of oral manipulation of pen mates may increase the percentage of PEN-affected pigs. According to these observations, PEN is a multifactorial condition which may have social causes among others.

Effect of the supplementation with a combination of plant extracts on sow and piglet performance and physiology during lactation and around weaning.

Weaning is a critical period for pigs. Some plant extracts showing antioxidant, anti-inflammatory or antibacterial properties, provided to piglets and/or their dam, may improve piglets' robustness at weaning, thus reducing the need for antobiotics. This study investigated the effects of a maternal and/or a direct supplementation of piglets with a combination of plant extracts on sow and piglet performance and their metabolic, immune, inflammatory, and oxidative status during lactation and around weaning. Sixty-four sows were assigned to the control or treated group. Treated sows were supplemented with a powdered plant extracts supplement daily top-dressed on feed from day of gestation (DG) 106 to day of lactation (DL) 28 and a liquid solution top-dressed on feed on DG109. Within each sow group, litters were divided into two groups: a control piglet group and a treated piglet group. A single dose of a liquid solution was orally given to piglets in the treated piglet group. Piglets were weaned on DL28. Blood samples were collected from sows on DG94, DG112, and DL26 and from 2 piglets per litter on DL3, DL14, DL25, and 5 d postweaning to analyze indicators of metabolic, immune, inflammatory, and oxidative status. Colostrum and milk samples were collected at farrowing, DL6, and 26. Maternal supplementation had no effect on sow metabolic, immune, inflammatory, and oxidative status except for fewer lymphocytes on DG112 (P < 0.05) and a lower plasma concentration of non-esterified fatty acids on DL26 (P < 0.05). Maternal supplementation tended to decrease dry matter and gross energy (P < 0.10) and reduced fat and haptoglobin concentrations (P < 0.01) in milk on DL26. Maternal supplementation had no effect on piglets' growth performance and blood indicators during lactation and around weaning. On DL25, the direct supplementation of piglets decreased their neutrophils proportion (P < 0.05), increased the expression of genes encoding pro- and anti-inflammatory cytokines in whole blood culture in response to lipopolysaccharide (P < 0.05) and tended to decrease the oxidative stress index (P = 0.06). After weaning, these beneficial effects were no longer observed but the supplementation improved piglets' growth performance during the postweaning period (P < 0.05). Plant extract supplementation could thus modify the composition of mammary secretions and improve postweaning performance of piglets potentially related to the modification of their immune and oxidative status before weaning.

Weaning is a critical period for piglets. Some plant extracts, known to exhibit antioxidant, anti-inflammatory, or antibacterial properties, may improve piglets' robustness at weaning. This study investigated the effects of a maternal and/or a direct supplementation of piglets with a combination of plant extracts on sow and piglet metabolic, immune, inflammatory, and oxidative status during lactation and around weaning. The maternal supplementation corresponded to a powdered supplement top-dressed on sow diet during late gestation and lactation and a liquid solution administered once 1 wk before parturition. The piglet supplementation was a liquid solution administered once on day 3 of age. The most concentrated components of the powder were extracts of fenugreek, Siberian ginseng, and cat's claw. The liquid solutions contained mostly oregano and eucalyptus essential oils. The maternal supplementation had few effects on sow immune, inflammatory, and oxidative status but modified milk composition at the end of lactation. It did not improve growth performance and the immune, inflammatory, and oxidative blood parameters of piglets around weaning. The direct supplementation of piglets modified their immune and oxidative status before weaning and increased their growth performance during the postweaning period, showing the potential of plant extracts as part of preventive strategies dedicated to improve piglets' robustness during the suckling and postweaning periods.

Hygiene of housing conditions and proinflammatory signals alter gene expressions in porcine adipose tissues and blood cells.

Adipose tissue is an organ with metabolic, endocrine and immune functions. In this tissue, the expressions of genes associated with several metabolic pathways, including lipid metabolism, have been shown to be affected by genetic selection for feed efficiency, an important trait to consider in livestock. We hypothesized that the stimulation of immune system caused by poor hygiene conditions of housing impacts the molecular and cellular features of adipose tissue and that the impact may differ between pigs that diverge in feed efficiency. At the age of 12 weeks, Large White pigs from two genetic lines divergent for residual feed intake (RFI) were housed in two contrasting hygiene conditions (good vs poor). After six weeks of exposure, pigs were slaughtered (n = 36). Samples of blood, subcutaneous (SCAT) and perirenal (PRAT) adipose tissues were collected for cell response and gene expression investigations. The decrease in the relative weight of PRAT was associated with a decline in mRNA levels of FASN, ME, LCN2 and TLR4 (P < 0.05) in pigs housed in poor conditions compared with pigs housed in good conditions for both RFI lines. In SCAT, the expressions of only two key genes (PPARG and TLR4) were significantly affected by the hygiene of housing conditions. Besides, the mRNA levels of both LCN2 and GPX3 were influenced by the RFI line (P < 0.05). Because we suspected an effect of poor hygiene at the cellular levels, we investigated the differentiation of stromal vascular cells isolated from SCAT in vitro in the absence or presence of a pro-inflammatory cytokine, Tumor Necrosis Factor-α (TNF-α). The ability of these cells to differentiate in the absence or presence of TNF-α did not differ among the four groups of animals (P > 0.05). We also investigated the expressions of genes involved in the immune response and lipid metabolism in whole blood cells cultured in the absence and presence of LPS. The hygiene conditions had no effect but, the relative expression of the GPX3 gene was higher (P < 0.001) in high RFI than in low RFI pigs while the expressions of IL-10 (P = 0.027), TGFß1 (P = 0.023) and ADIPOR2 (P = 0.05) genes were lower in high RFI than in low RFI pigs. Overall, the current study indicates that the hygiene of housing had similar effects on both RFI lines on the expression of genes in adipose tissues and on the features of SCAT adipose cells and whole blood cells in response to TNF-α and LPS. It further demonstrates that the number of genes with expression impacted by housing conditions was higher in PRAT than in SCAT. It suggests a depot-specific response of adipose tissue to the current challenge.

Pathogen exposure influences immune parameters around weaning in pigs reared in commercial farms.

BACKGROUND: Multiple antigenic stimulations are crucial to immune system training during early post-natal life. These stimulations can be either due to commensals, which accounts for the acquisition and maintenance of tolerance, or to pathogens, which triggers immunity. In pig, only few works previously explored the influence of natural exposition to pathogens upon immune competence. We propose herein the results of a multicentric, field study, conducted on 265 piglets exposed to contrasted pathogen levels in their living environment. Piglets were housed in 15 different commercial farms, sorted in two groups, low (HSLOW)- and high (HSHIGH)-health status farms, depending on their recurrent exposition to five common swine pathogens. RESULTS: Using animal-based measures, we compared the immune competence and growth performances of HSLOW and HSHIGH pigs around weaning. As expected, we observed a rise in the number of circulating leucocytes with age, which affected different cell populations. Monocyte, antigen-experienced and cytotoxic lymphocyte subpopulation counts were higher in piglets reared in HSLOW farms as compared to their HSHIGH homologs. Also, the age-dependent evolution in γδ T cell and neutrophil counts was significantly affected by the health status. With age, circulating IFNα level decreased and IgM level increased while being greater in HSLOW piglets at any time. After weaning, LPS-stimulated blood cells derived from HSLOW piglets were more prone to secrete IL-8 than those derived from HSHIGH pigs did. Monocytes and granulocytes issued from HSLOW pigs also exhibited comparable phagocytosis capacity. Altogether our data emphasize the more robust immunophenotype of HSLOW piglets. Finally, piglets raised under higher pathogen pressure grew less than HSHIGH piglets did and exhibited a different metabolic profile. The higher cost of the immune responses associated with the low farm health status may account for lower HSLOW piglet performances. CONCLUSIONS: Altogether, our data, obtained in field conditions, provide evidence that early exposure to pathogens shapes the immune competence of piglets. They also document the negative impact of an overstimulation of the immune system on piglets' growth.

Improving maternal welfare during gestation has positive outcomes on neonatal survival and modulates offspring immune response in pigs.

Improving the housing of pregnant sows by giving them more space and access to deep straw had positive effects on their welfare, influenced their maternal behavior and improved the survival of their offspring. The present study aimed at determining whether these effects were actually due to environmental enrichment and whether the provision of straw pellets and wood can partly mimic the effects of straw bedding during gestation. Three graded levels of enrichment were used, that were, collective conventional pens on slatted floor (C, n = 26), the same pens with manipulable wood materials and distribution of straw pellets after the meals (CE, n = 30), and larger pens on deep straw litter (E, n = 27). Sows were then housed in identical farrowing crates from 105 days of gestation until weaning. Decreased stereotypies, blood neutrophils, and salivary cortisol, and increased behavioral investigation indicated that health and welfare of sows during gestation were improved in the E environment compared with the C environment. The CE sows responded as C or E sows depending on the trait. Piglet mortality rate in the first 12 h after birth was lower in E and CE litters than in C litters, but enrichment level during gestation had only small effects on lactating sow behavior and milk composition postpartum. On days 2 and 3 of lactation, E sows interrupted less often their nursing sequences than C and CE sows. On day 2, milk from both E and CE sows contained more minerals than that from C sows. In one-day-old piglets, the expression levels of genes encoding toll-like receptors (TLR2, TLR4) and cytokines (interleukin-1, -6 and -10) in whole blood after 20-h culture, were greater in E piglets than in CE or C piglets. In conclusion, housing sows in an enriched environment during gestation improved early neonatal survival, probably via moderate and cumulative positive effects on sow behavior, milk composition, and offspring innate immune response. The gradation in the effects observed in C, CE and E housing environment reinforced the hypothesis of a causal relationship between maternal environmental enrichment, sow welfare and postnatal piglet traits.

Evaluation of the potential benefits of iron supplementation in organic pig farming.

Background: Iron from the stock acquired during foetal life and the ingestion of milk is not sufficient to cover the needs of the piglets during their first weeks of life. In organic farming, systematic supplementation with iron is problematic due to a strong limitation in pharmaceutic treatments. Methods: Erythroid parameters around weaning were measured in piglets from organic outdoor and indoor farms, and related to indicators of the inflammatory status. Blood samples were collected from 28.9±2.6 piglets/herd at 42.0±3.2 days of age and 11.9±3.0 kg live weight (mean ± SD) in 21 farms from the west part of France. Among the 11 outdoor farms, only one had supplemented piglets with 200 mg iron while among the 10 indoor farms, only one had not supplemented piglets, one had supplemented them with 100 mg, 8 with 200 mg and one with 400 mg. Results: Compared to outdoor piglets without supplementation, piglets kept indoors and receiving 200 mg iron had lower haemoglobin concentration (105 vs 118±2 g/l, mean ± SE) and red blood cell volume (56 vs 60±1 fl) (P<0.005). The reduction in haemoglobin concentration and red blood cell volume was more pronounced in indoor piglets supplemented with 100 mg of iron and even more when they had not received iron. The plasma concentration of haptoglobin was lower in outdoor than in indoor piglets (0.51±0.06 vs 0.78±0.09 g/l) whereas no effect of housing was observed for markers of oxidative stress (dROM, BAP). In the 14 farms where sow parity was known, the haemoglobin concentration was lower in piglets from primiparous than from multiparous sows (109 versus 114±2 g/l, P < 0.001). Conclusion: With the exception of soils where the content of bioavailable iron is very low, piglets from outdoor farms do not require iron supplementation, unlike those raised indoors.

The fecal microbiota of piglets during weaning transition and its association with piglet growth across various farm environments.

This study describes the fecal microbiota from piglets reared in different living environments during the weaning transition, and presents the characteristics of microbiota associated with good growth of piglets after weaning. Fecal samples were collected pre- (d26) and post-weaning (d35) from 288 male piglets in 16 conventional indoor commercial farms located in the West of France. The changes one week after weaning on the most abundant microbial families was roughly the same in all farms: alpha diversity increased, the relative abundance of Bacteroidaceae (-61%), Christensenellaceae (-35%), Enterobacteriaceae (-42%), and Clostridiaceae (-32%) decreased, while the relative abundance of Prevotellaceae (+143%) and Lachnospiraceae (+21%) increased. Among all the collected samples, four enterotypes that were ubiquitous in all farms were identified. They could be discriminated by their respective relative abundances of Prevotella, Faecalibacterium, Roseburia, and Lachnospira, and likely corresponded to a gradual maturational shift from pre- to post-weaning microbiota. The rearing environment influenced the frequency of enterotypes, as well as the relative abundance of 6 families at d26 (including Christensenellaceae and Lactobacillaceae), and of 21 families at d35. In all farms, piglets showing the highest relative growth rate during the first three weeks after weaning, which were characterized as more robust, had a higher relative abundance of Bacteroidetes, a lower relative abundance of Proteobacteria, and showed a greater increase in Prevotella, Coprococcus, and Lachnospira in the post-weaning period. This study revealed the presence of ubiquitous enterotypes among the farms of this study, reflecting maturational stages of microbiota from a young suckling to an older cereal-eating profile. Despite significant variation in the microbial profile between farms, piglets whose growth after weaning was less disrupted were, those who had reached the more mature phenotype characterized by Prevotella the fastest.

Postprandial insulin and nutrient concentrations in lipopolysaccharide-challenged growing pigs reared in thermoneutral and high ambient temperatures1.

The aim of this study was to evaluate the associated effects of ambient temperature and inflammation caused by repeated administration of Escherichia coli lipopolysaccharide (LPS) on insulin, energy, and AA metabolism. Twenty-eight pigs were assigned to one of the two thermal conditions: thermoneutral (24 °C) or high ambient temperature (30 °C). The experimental period lasted 17 d, which was divided into a 7-d period without LPS (days -7 to -1), and a subsequent 10-d LPS period (days 1 to 10) in which pigs were administered 5 repeated injections of LPS at 2-d intervals. Postprandial profiles of plasma insulin and nutrients were evaluated through serial blood samples taken on days -4 (P0), 4 (P1), and 8 (P2). Before the LPS-challenge (P0), postprandial concentrations of glucose, lactate, Gln, Ile, Leu, Phe, Tyr, and Val were greater in pigs kept at 24 °C than at 30 °C (P < 0.05). In contrast, Arg, Asp, Gly, His, and Met postprandial concentrations at P0 were lower at 24 °C than at 30 °C (P < 0.05). At both 24 and 30 °C conditions, pigs had greater postprandial concentrations of insulin (P < 0.01) and lower concentrations of NEFA (P < 0.01) and α-amino nitrogen (P < 0.05) at P1 and P2 than at P0. Compared with P0, postprandial concentrations of glucose were greater (P < 0.05) at P1 in pigs kept at 24 °C, and at P1 and P2 in pigs kept at 30 °C. At both ambient temperatures, pigs had lower (P < 0.05) postprandial concentrations of Ala, Gly, His, Ile, Leu, Pro, Ser, Thr, Trp, and Val at P1 and P2 than at P0. Arginine postprandial concentration at P1 was lower than at P0 in pigs kept at 24 °C (P < 0.05), whereas no difference was observed in pigs at 30 °C. Relative to P0, Gln and Tyr concentrations were lower at P1 and P2 in pigs kept at 24 °C (P < 0.01), whereas lower Gln concentration was observed only at P2 (P < 0.01) and lower Tyr only at P1 (P < 0.01) in pigs kept at 30 °C. Our study shows a hyperglycemic and hyperinsulinemic state in LPS-challenged pigs and a greater magnitude of this response in pigs kept at 30 °C. Furthermore, LPS caused important changes in BCAA, His, Thr, and Trp profiles, suggesting the role these AA in supporting the inflammatory response. Finally, our results suggest that LPS-induced effects on postprandial profiles of specific AA (Arg, Gln, Phe, and Tyr) may be modulated by ambient temperature.

Effects of age and weaning conditions on blood indicators of oxidative status in pigs.

Weaning is a source of social, nutritional and environmental disorders that challenge piglet health. This study assesses the relevance of using plasma indicators of oxidative status as biomarkers of health around weaning in pigs. Blood antioxidant potential (BAP), hydroperoxides (HPO), oxidative stress index (OSI, e.g. HPO/BAP), vitamin A and E concentrations were investigated in two different trials. Trial A was carried out in an experimental unit to investigate the effects of age (from 12 to 147 days of age), weaning (at 21 or 28 days of age) and management at weaning (in optimal (OC) or deteriorated (DC) conditions) on those parameters. Trial B was performed in 16 commercial pig farms to describe the variability of these indicators on field between 26 and 75 days of age. In trial A, between 12 and 147 days of age, HPO globally increased (P < 0.001), vitamin E concentration decreased (P < 0.001) whereas BAP and vitamin A concentration remained relatively stable (P > 0.1). Vitamins E and A concentrations dropped 5 days after weaning independently of weaning age, weaning conditions and expression of diarrhea (P < 0.001). Twelve days after weaning, whatever the weaning age, HPO and OSI increased in DC compared to OC piglets (P = 0.05 and P < 0.01) and in piglets exhibiting diarrhea compared to those without diarrhea (P < 0.01 and P < 0.001). In DC pigs, BAP was also decreased (P < 0.05) 12 days after weaning. On trial B, plasma concentrations of vitamins A and E decreased and HPO increased 5 and 19 days respectively after weaning (P < 0,001). Contrarily to trial A, BAP values did not drop after weaning. Piglets which had the lowest ADG (Average Daily Gain) after weaning had greater HPO and OSI and lower vitamin A and E concentrations after weaning but also lower vitamin E concentration before weaning (P < 0.05). In conclusion, HPO or OSI seem to be good indicators of health disorders around weaning and plasma concentration of vitamin E before weaning is associated to growth after weaning.

Housing Systems Influence Gut Microbiota Composition of Sows but Not of Their Piglets.

Different housing systems can be used in pig production and little is known about their effect on gut microbiota composition. In this study we characterized fecal microbiota by sequencing the rRNA genes in sows kept during gestation in conventional pens with a slatted floor and in enriched pens with a floor covered with deep straw. After farrowing, microbiota of 1- and 4-day-old piglets were also monitored. Microbiota of sows from the enriched system contained significantly more Prevotella, Parabacteroides, CF231, Phascolarctobacterium, Fibrobacter, Anaerovibrio and YRC22 and significantly less Lactobacillus, Bulleidia, Lachnospira, Dorea, Ruminococcus and Oscillospira than microbiota of sows from the conventional system. The Firmicutes to Bacteroidetes ratio was 0.96 in the microbiota of sows kept in the enriched pens and this increased to 1.66 in the microbiota of sows kept in the conventional system. The production system therefore influenced microbiota composition, most likely due the ingestion of the straw. The microbiota of 1- and 4-day-old piglets differed from the microbiota of sows and sows therefore did not represent the most important source for their colonization in early days of life.

Transcriptomes of whole blood and PBMC in chickens.

Global transcriptome analysis of chicken whole blood to discover biomarkers of different phenotypes or physiological disorders has never been investigated so far. Whole blood provides significant advantages, allowing large scale and non-invasive sampling. However, generation of gene expression data from the blood of non-mammalian species remains a challenge, notably due to the nucleated red blood cells, hindering the use of well-established protocols. The aim of this study was to analyze the relevance of using whole blood cells (WB) to find biomarkers, instead of Peripheral Blood Mononuclear Cells (PBMC), usually chosen for immune challenges. RNA sources from WB and PBMC was characterized by microarray analysis. Our results show that the quality and quantity of RNA obtained from WB was suitable for further analyses, although the quality was lower than that from PBMC. The transcriptome profiling comparison revealed that the majority of genes were expressed in both WB and PBMC. Hemoglobin subunits were the major transcripts in WB, whereas the most enriched biological process was related to protein catabolic process. Most of the over-represented transcripts in PBMC were implicated in functions specific to thrombocytes, like coagulation and platelet activation, probably due to the large proportion of this nucleated cell type in chicken PBMC. Functions related to B and T cells and to other immune functions were also enriched in the PBMC subset. We conclude that WB is more suitable for large scale immunity oriented studies and other biological processes that have been poorly investigated so far.

Effect of feed restriction on performance and postprandial nutrient metabolism in pigs co-infected with Mycoplasma hyopneumoniae and swine influenza virus.

As nutritional status and inflammation are strongly connected, feeding and nutritional strategies could be effective to improve the ability of pigs to cope with disease. The aims of this study were to investigate the impact of a feed restriction on the ability of pigs to resist and be tolerant to a coinfection with Mycoplasma hyopneumoniae (Mhp) and the European H1N1 swine influenza virus, and the consequences for nutrient metabolism, with a focus on amino acids. Two groups of specific pathogen-free pigs were inoculated with Mhp and H1N1 21 days apart. One group was fed ad libitum, the other group was subjected to a two-week 40% feed restriction starting one week before H1N1 infection. The two respective mock control groups were included. Three days post-H1N1 infection, 200 g of feed was given to pigs previously fasted overnight and serial blood samples were taken over 4 hours to measure plasma nutrient concentrations. Throughout the study, clinical signs were observed and pathogens were detected in nasal swabs and lung tissues. Feed-restricted pigs presented shorter hyperthermia and a positive mean weight gain over the 3 days post-H1N1 infection whereas animals fed ad libitum lost weight. Both infection and feed restriction reduced postprandial glucose concentrations, indicating changes in glucose metabolism. Post-prandial plasma concentrations of the essential amino acids histidine, arginine and threonine were lower in co-infected pigs suggesting a greater use of those amino acids for metabolic purposes associated with the immune response. Altogether, these results indicate that modifying feeding practices could help to prepare animals to overcome an influenza infection. Connections with metabolism changes are discussed.

Effect of repeated administration of lipopolysaccharide on inflammatory and stress markers in saliva of growing pigs.

Although saliva could be considered to be an ideal biological sample for evaluation of biomarkers relating to stress and inflammatory responses in pigs, little is known about how these might be influenced by the presence of endotoxaemia. In the present study, the response to repeated administrations of lipopolysaccharide (LPS) was investigated, using a panel of salivary stress markers such as chromogranin A (CgA) and cortisol, as well as inflammatory/immune markers such as haptoglobin (Hp), C-reactive protein (CRP) and immunoglobulin A (IgA). Sixteen growing pigs were adapted to experimental conditions for 3 weeks, after which, 10 of the pigs were selected to receive three doses of LPS at 48 h intervals. Saliva samples were taken from all pigs prior to any LPS administration (baseline) and at time points corresponding to 3 h after each injection of LPS (T1, T2 and T3). Results showed that repeated administration of LPS induced significant elevation of salivary markers of hypothalamic-pituitary-adrenal (cortisol) and immune (Hp, CRP and IgA) activity compared to baseline levels (P < 0.05). However, rectal temperature, CRP and cortisol data suggested that the amplitude of the inflammatory response decreased with successive LPS administrations. Thus, measurement of salivary biomarkers could be a practical tool for evaluating the inflammatory response to endotoxaemia in pigs. In the case of chronic inflammatory states, salivary Hp and IgA might be more sensitive markers than CRP or cortisol.

High ambient temperature alleviates the inflammatory response and growth depression in pigs challenged with Escherichia coli lipopolysaccharide.

Pig production has increased in hot climate countries over recent years, but the effect of exposure to high temperatures on the health status of farm animals has not been investigated thoroughly. It is not clear how the ambient temperature (Ta) might influence responses to inflammatory challenge in pigs. The aim of the present study was to evaluate the effects of high Ta on performance and physiological parameters of growing pigs, subjected to repeated administration of Escherichia coli lipopolysaccharide (LPS). Thirty-seven pigs, each fitted with a jugular catheter, were assigned to one of two Ta conditions: thermo-neutral (TN, 24 °C) or high (HT, 30 °C). After a 14-day adaptation period, and a 7-day measurement period, pigs were administered five repeated injections of LPS at 48 h intervals. Irrespective of Ta, the LPS challenge reduced feed consumption and increased plasma pro-inflammatory cytokines, haptoglobin and cortisol. However, the extent of these responses was greater in pigs at TN than HT. In both groups, plasma thyroxine and triiodothyronine concentrations decreased, following the first LPS injection and thereafter returned to baseline, which occurred faster at HT than at TN. Moreover, the LPS challenge decreased growth and feed efficiency in pigs kept at TN, which was not observed in pigs kept at HT. The results suggest a greater capacity of pigs to limit the physiological and metabolic disturbances caused by inflammatory challenge, when kept at HT, compared to TN.

Tryptophan metabolism, from nutrition to potential therapeutic applications.

Tryptophan is an indispensable amino acid that should to be supplied by dietary protein. Apart from its incorporation into body proteins, tryptophan is the precursor for serotonin, an important neuromediator, and for kynurenine, an intermediary metabolite of a complex metabolic pathway ending with niacin, CO(2), and kynurenic and xanthurenic acids. Tryptophan metabolism within different tissues is associated with numerous physiological functions. The liver regulates tryptophan homeostasis through degrading tryptophan in excess. Tryptophan degradation into kynurenine by immune cells plays a crucial role in the regulation of immune response during infections, inflammations and pregnancy. Serotonin is synthesized from tryptophan in the gut and also in the brain, where tryptophan availability is known to influence the sensitivity to mood disorders. In the present review, we discuss the major functions of tryptophan and its role in the regulation of growth, mood, behavior and immune responses with regard to the low availability of this amino acid and the competition between tissues and metabolic pathways for tryptophan utilization.

Dynamics of serum antibodies to and load of porcine circovirus type 2 (PCV2) in pigs in three finishing herds, affected or not by postweaning multisystemic wasting syndrome.

BACKGROUND: Despite that PMWS commonly affects pigs aged eight to sixteen weeks; most studies of PMWS have been conducted during the period before transfer to finishing herds. This study focused on PCV2 load and antibody dynamics in finishing herds with different PMWS status. METHODS: Sequentially collected blood samples from 40 pigs in each of two Swedish (A and B) and one Norwegian (C) finishing herds were analysed for serum PCV2-load and -antibodies and saliva cortisol. The two Swedish herds differed in PMWS status, despite receiving animals from the same sow pool (multi-site production). However, the PMWS-deemed herd (A) had previously also received pigs from the spot market. RESULTS: The initial serum PCV2 load was similar in the two Swedish herds. In herd A, it peaked after two weeks in the finishing herd and a high number of the pigs had serum PCV2 levels above 107 per ml. The antibody titres increased continually with exception for the pigs that developed PMWS, that had initially low and then declining antibody levels. Pigs in the healthy herd B also expressed high titres of antibodies to PCV2 on arrival but remained at that level throughout the study whereas the viral load steadily decreased. No PCV2 antibodies and only low amounts of PCV2 DNA were detected in serum collected during the first five weeks in the PMWS-free herd C. Thereafter a peak in serum PCV2 load accompanied by an antibody response was recorded. PCV2 from the two Swedish herds grouped into genotype PCV2b whereas the Norwegian isolate grouped into PCV2a. Cortisol levels were lower in herd C than in herds A and B. CONCLUSIONS: The most obvious difference between the Swedish finishing herds and the Norwegian herd was the time of infection with PCV2 in relation to the time of allocation, as well as the genotype of PCV2. Clinical PMWS was preceded by low levels of serum antibodies and a high load of PCV2 but did not develop in all such animals. It is notable that herd A became affected by PMWS after errors in management routine, emphasising the importance of proper hygiene and general disease-preventing measures.

Comparative effects of a prenatal stress occurring during early or late gestation on pig immune response.

The aim of this work was to investigate the immune effects of prenatal stress (PNS) in pigs, when maternal stressor is applied during early or late gestation. In two separate experiments, gilts were submitted to a social-stress routine between either days 24 and 48 (stress (S) group, n=8 vs. control (C) group, n=6) or days 79 and 103 of gestation (S group, n=10 vs. C group, n=7). During the first month of life of the piglets, their cortisol levels were assessed in basal state and after stressful events (castration, new environment, and weaning). Piglets were immunized against ovalbumin (OVA) at 7 (D7) and 19 (D19) days of age. Lymphocyte proliferation in response to OVA and mitogens was investigated in blood in both sexes from D5 to D29 as well as in the spleen, thymus and crural lymph nodes from females euthanized on D5 and D26. On D27, the cytokine response of male piglets to an injection of lipopolysaccharide was investigated. Special care was taken to minimize the stress at blood sampling and euthanasia. We found that early gestational stress only affected the relative weight of adrenals on D5 (S

Regulator of G protein signalling 16 is a target for a porcine circovirus type 2 protein.

Interaction studies have suggested that the non-structural protein encoded by open reading frame 3 (ORF3) of porcine circovirus type 2 (PCV2) binds specifically to a regulator of G protein signalling (RGS) related to human RGS16 (huRGS16). The full-length clone of RGS16 was generated from porcine cells and sequence analysis revealed a close relationship to huRGS16 and murine RGS16. In vitro pull-down experiments verified an interaction between porcine RGS16 (poRGS16) and ORF3 from PCV2. Using GST-linked ORF3 proteins from three different genogroups of PCV2 and from porcine circovirus type 1 (PCV1) in the pull-down experiments indicated that there were differences in their ability to bind poRGS16. Quantitative RT-PCR demonstrated that the expression of poRGS16 mRNA could be induced by a number of cell activators including mitogens (LPS and PHA), interferon inducers (ODN 2216 and poly I : C) and the neurotransmitter norepinephrine. Immunofluorescence labelling confirmed the induced expression of poRGS16 at the protein level and suggested that the PCV2 ORF3 protein co-localized with poRGS16 in LPS-activated porcine PBMC. Furthermore, poRGS16 appeared to participate in the translocation of the ORF3 protein into the cell nucleus, suggesting that the observed interaction may play an important role in the infection biology of porcine circovirus.

Maternal stress during late gestation has moderate but long-lasting effects on the immune system of the piglets.

Events acting prenatally on developing foetuses are important determinants for disorders later in life. Prenatal stress (PNS) is one of these events. The purpose of this study was to determine the consequences of a repeated social stress applied during late gestation of the pregnant gilt on the immune system and hypothalamo-pituitary-adrenal (HPA) axis activity of the piglets from birth to two months of age. Pregnant gilts were submitted to repeated social stress which was induced by housing unfamiliar gilts in pairs modified twice a week during 4 weeks between days 77 and 105 of gestation (S group, n=18). Control gilts were housed in stable pairs during the same period (C group, n=18). Blood cortisol, haptoglobin and IgG levels, immune cell counts, mitogen-induced whole-blood proliferation and TNF-alpha production were evaluated in piglets at 4 days of age (D4), before and after weaning (D26 and 28) and before and after relocation to a new building (D60 and 62). We found that PNS did not affect growth rate of the progeny. It decreased the relative weight of adrenal glands on D4 (P<0.05) but plasma cortisol levels were similar in both groups at all ages. IgG levels in colostrum and in the serum of piglets were not affected. PNS decreased the total numbers of white blood cells, lymphocytes and granulocytes from D26 to D60 (P<0.05), the CD4(+)/CD8(+) T cell ratio on D4 (P<0.05), and LPS induced-TNF-alpha production on D60 (P<0.05). PNS increased the ConA-induced lymphocyte proliferation on D4 and D60 and the PWM-induced proliferation on D60 (P<0.05). Our results demonstrate that a repeated social stress applied to pregnant sows during late gestation can induce long-lasting effects on several parameters of the immune function of the offspring. These effects are not due to modifications of the HPA axis activity and may impair the abilities of the piglets to efficiently react against infections during the suckling period and around weaning.

Immune alterations induced by social defeat do not alter the course of an on-going BCG infection in mice.

The timing for applying stressor and primary immunization is known to influence the nature of the immune alterations induced by stress. The aim of the present study was to investigate the consequences of a stress occurring several days after the beginning of a primary infection on the host resistance. For this purpose, we investigated the effects of repeated social defeat on the immune response of mice infected with BCG 11 days before. In vitro production of cytokines in response to LPS or tuberculin, and the sensitivity of spleen cells to corticosterone were assessed 8 days after the end of the stress. Bacterial growth was assessed in the spleen. We demonstrated that social defeat in BCG-infected mice induced a long-term increase in IL-6 and IL-10 production in response to LPS but did not modify the sensitivity of spleen cells to corticosterone. Stress did not affect the specific response to BCG, as shown by the production of cytokines in tuberculin-stimulated cultures. Accordingly, social defeat was unable to influence the mycobacterial growth in vivo. These results support the hypothesis postulating that stress does not affect antigen-specific response when it is applied after priming.