Piglets are highly susceptible to iron deficiency. This randomized clinical trial evaluated the effectiveness of four iron dosing schemes in preventing anemia. Two herds with different farrowing management systems were included. In each herd, 40 litters (6 piglets/litter) were selected on day 3 of age. A 2 × 2 factorial design was applied, combining two intramuscular iron dextran injection schemes [37.5 mg Fe/kg (low injection; LI) or 150 mg Fe/kg (high injection; HI)] with two oral ferrous sulphate feed supplementation schemes [125 mg Fe/kg (low feed; LF) or 200 mg Fe/kg (high feed; HF)]. Blood samples were collected at 4 and 20 days of age, and piglets were weighed at 3 and 20 days. Data were analyzed using linear mixed models, with significance set at p < 0.05. In Herd A, HI-LF piglets showed increased body weight, whereas no growth differences were observed in Herd B. Creep-feed intake did not differ between treatments. HI consistently improved red-cell indices in Herd A, while in Herd B LI piglets initially showed higher values at day 4, but HI piglets surpassed them by day 20. Leukocyte responses were limited. High-dose iron injections were effective in preventing anemia, while oral supplementation had minimal impact.

Vaccination is an important control measure against infections with Mycoplasma hyopneumoniae (M. hyopneumoniae), the primary pathogen of enzootic pneumonia in pigs. The present study investigated local and systemic humoral and cell-mediated immune responses and efficacy upon vaccination of piglets with a combined vaccine containing inactivated M. hyopneumoniae and porcine circovirus 2d (Cirbloc® M Hyo, Ceva), followed by experimental M. hyopneumoniae infection (D21). Forty-five piglets were allocated to three groups, namely the not-vaccinated and infected (C) (n = 20), vaccinated and infected (V) (n = 20), and not-vaccinated and not-infected (NC) groups (n = 5). Vaccination was applied once (D0) intramuscularly. Four pigs from the V and C groups were euthanized 2 weeks post-infection (D35), and the remaining pigs 2 weeks later (D49). Blood, lung tissue, bronchoalveolar lavage fluid (BALF), and bronchial lymph nodes were collected at different timepoints. Piglets in the V group exhibited seroconversion on days 21 and 35, with markedly elevated levels of specific IgA and IgG in BALF on D35. Furthermore, the V group showed activation of interferon (IFN)-γ+/tumor necrosis factor (TNF)-α+ CD4+CD8α+ T cells and T cell proliferation on day 7, with these responses remaining elevated through D21. The concentrations of interleukin (IL)-1β, TNF-α, C–X–C motif chemokine ligand 8 (CXCL-8), and IL-17A in BALF of the C group were higher on D49, correlating with higher M. hyopneumoniae DNA loads. Clinical signs and lung lesions were less severe in vaccinated pigs. The combined vaccine elicited robust M. hyopneumoniae-specific humoral and cellular responses in blood and enhanced post-infection cellular immunity in draining lymph nodes, underscoring its protective efficacy.

Mycoplasma infections pose a significant challenge in swine production because of their economic impact and the difficulties associated with diagnosis and treatment. Antimicrobials are often the only available option for combating mycoplasmoses despite reports of resistance to several molecules and the frequent chronic nature of infections, which can reduce treatment efficacy. This study aimed to investigate the use of antimicrobials against swine mycoplasmoses through an international field survey and to review the relevant scientific literature and regulatory recommendations. The survey was led by the MyMIC network, whose main objective is to standardise antimicrobial susceptibility testing (AST) methods for livestock mycoplasmas. The responses of 118 swine veterinarians across 25 countries were analysed. No significant variations in practices were observed between countries. Macrolides, tetracyclines, and pleuromutilins were the most prescribed antimicrobial classes (used in more than 40

This manuscript reviews current knowledge on Mycoplasma hyopneumoniae, the primary agent of enzootic pneumonia in pigs, integrating advances in epidemiology, pathogenesis, immunity, diagnostics, and control. The pathogen is globally endemic, with transmission driven mainly by direct contact within a herd, and by purchase of animals and airborne transmission between herds. Infection dynamics are shaped by production systems, sow-piglet transmission, and co-infections, while strain diversity and subclinical infections complicate disease expression and control. Pathogenesis is understood as a complex, multifactorial phenomenon rather than being determined by single virulence factors. Adhesion, biofilm formation, extensive posttranslational processing, metabolic adaptation, and immune evasion collectively enable persistent colonization. A major conceptual advance is the discovery of migrasome-mediated dissemination, which may explain chronic infection and reduced antimicrobial efficacy. Despite significant advances, important knowledge gaps remain in multiple areas of Mycoplasma hyopneumoniae research. Uncertainties persist in transmission and epidemiology, including the role of environmental spread, wild boar reservoirs, and the extent of subclinical infections. The impact of strain diversity on virulence, transmission, persistence, and vaccine performance is not yet fully understood, and predictive markers are lacking. Key aspects of host–pathogen interactions, such as immune evasion, occasional intracellular survival, macrophage polarization, and the in vivo relevance of migrasome-mediated dissemination, require further clarification. Protective immunity remains poorly defined, with unresolved questions on correlates of protection and the roles of mucosal and systemic responses. Diagnostic challenges include distinguishing active from residual infection and improving specificity and Differentiating Infected from Vaccinated Animals (DIVA) compatibility. Evidence on antimicrobial effects on transmission and resistance monitoring is limited. In addition, variability in vaccine efficacy and the influence of maternal immunity remain unclear. Finally, scalable elimination strategies, particularly for very large production systems and reduced antimicrobial use, are still needed.

This review critically reflects on the use of immunocrit in neonatal piglets as an indicator of passive immunity status. Under intensive production conditions and with the development of hyperprolific sow lines, reliable techniques are required to objectively assess the success of passive immunity transfer to the piglets. The immunocrit is a cost-effective indirect method for assessing immunoglobulin concentration in serum or plasma samples obtained 12-48 h after the birth of the first piglet, by using the principle of protein precipitation. Reduced growth performance, delayed development, greater vulnerability to illness, and higher pre-weaning mortality are all consistently associated with low immunocrit readings. Higher numbers, on the other hand, indicate effective immunoglobulin absorption and better long-term productivity. Various management strategies, including split suckling, cross-fostering, and farrowing system design, directly influence immunocrit values by affecting colostrum intake and competition among piglets. Certain interventions, such as oxytocin administration or anti-inflammatory treatments, may influence colostrum composition or farrowing conditions, but they do not always result in appreciable changes in immunocrit levels. Its usefulness, quickness, and field application make it an important tool in contemporary swine production, even though it lacks the analytical precision of enzyme-linked immunosorbent assay and radial immunodiffusion that quantify individual immunoglobulin isotypes, such immunoglobulin G. For herd level interpretations the immunocrit results should be complementary to the evaluation of the farrowing and colostrum management practices, the sow diet and the handling of the piglets in supporting corrective measures prenatally.

The often disappointing intake of creep feed by suckling piglets coincides with a limited ability to cope with challenges such as weaning diarrhoea. Investigating the dietary nutrient profile of piglets (Sus scrofa) in the wild may help to improve nutrition for farmed piglets. This study was conducted to analyse the stomach content of feral piglets and their farmed counterparts, and to compare them with the composition of commercial creep feeds. Forty feral piglets (4.6 ± 1.4 kg) living in a wild herd were tracked and legally hunted in the Bahía Samborombón (Buenos Aires, Argentina). Their gastric contents were collected for analysing macronutrients. Twenty-eight farmed suckling piglets of similar ages were sourced from a Dutch research farm, and their stomach contents were collected and pooled into fourteen samples with the same procedure for comparison. Additionally, the composition data of twenty-five commercial feeds was also collected. A higher dry matter content was observed in the farmed piglets’ stomachs (233 vs. 148 g/kg, P < 0.05). The gastric crude protein concentration was similar between both groups but the crude fat concentration was higher in the stomach of farmed animals (525 vs. 238 g/kg DM, P < 0.05), while feral piglets consumed more ash and fibre (P < 0.05). A similar concentration of non-fibrous carbohydrates (NFC) on metabolizable energy basis was observed by calculation through the NRC’s guideline (P > 0.05). Within the fibre content, significantly greater concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were observed in the stomach of feral piglets than in those of farmed piglets (282 vs. 36 g/kg, 158 vs. 9 g/kg DM, 53 vs. 3 g/kg DM, respectively, P < 0.05). Similar protein concentrations were observed between the gastric content of feral piglets and creep feed, while significantly higher crude ash and crude fat concentrations were found in feral piglets’ consumption (P < 0.05). In conclusion, piglets in natural conditions consume much more fibre—from coarse plant material—compared to farmed piglets receiving creep feed. Although technical performance is distinctly different between nature and farm, it raises the question whether suckling piglets under farming conditions would benefit from a more fibrous and coarser creep feed.

Vaccination against Mycoplasma hyopneumoniae is still carried out worldwide, but unfortunately current commercial vaccines only provide partial protection. Therefore, two M. hyopneumoniae strains were genetically modified by transposon-mediated gene disruption of mmsA and mnuA, encoding methylmalonate semialdehyde dehydrogenase and membrane nuclease A, respectively. We investigated how immune responses elicited by these genetically modified M. hyopneumoniae strains protected pigs against challenge infection. An endotracheal single dose vaccination with genetically modified M. hyopneumoniae strain 1 (ΔmmsA) or 2 (ΔmnuA), or physiological saline solution (Control) was followed by challenge infection. Piglets from ΔmnuA had a higher respiratory disease score post-vaccination, but this group coughed significantly less after challenge. Significantly fewer DNA copies of the challenge strains were observed in broncho-alveolar lavage fluid (BAL) from ΔmnuA after challenge. Two weeks post-challenge, significantly more BAL IgG and BAL IgA was observed in ΔmnuA, but at euthanasia significantly more IgA and less pro-inflammatory cytokines were detected in BAL from both vaccinated groups. Furthermore, a significantly lower percentage of IFN-γ+ and TNF-α+IFN-γ+ CD8+ T cells was observed after administration of ΔmnuA. The percentage of IFN-γ+ CD8+ T cells was significantly lower in ΔmmsA at euthanasia. To conclude, the results of this exploratory study show that a single endotracheal administration of ΔmnuA resulted in coughing post-vaccination, but reduced clinical signs post-challenge and challenge strain DNA load in BAL. Therefore, a strain mutated in the mnuA gene might be an interesting mutant strain that could be promising as a potential live vaccine candidate strain as it can reduce M. hyopneumoniae infection burden under field conditions.

Mammary growth is a major determinant of potential sow milk yield. Estrogens are important for mammogenesis in growing gilts, as evidenced by the increased rate of mammary development occurring at puberty. Mammary gland involution involves losses of over two-thirds of the parenchymal mass and cells present on the day of weaning. Lactogenesis is the ability of the mammary gland to synthesize milk components such as lactose, casein, and lipids and is often described as a two-phase process. Suckling and milk removal are the major stimuli for mammary growth and milk output during lactation. The stimulus of piglets suckling or massaging the mammary glands leads to increases in circulating prolactin, a galactopoietic hormone. Energy deficit is one of the main predisposing risk factors for piglet mortality, and it was recently shown that energy supplementation could be a way of increasing survival of lightweight piglets.

Sow mortality is a critical issue in intensive pig farming, impacting animal welfare, farm sustainability, and profitability. This study investigated the occurrence and causes of sow mortality on 15 Flemish sow farms, focusing on management practices, housing conditions, feeding strategies, and genetics. The average sow mortality rate across the farms was 11.4% in 2022, which decreased to 8.1% in 2023 following the implementation of targeted control measures. Necropsies performed on 100 deceased sows, coming from the 15 different farms, revealed that the primary causes of mortality were positional changes in internal organs (32%), arthritis (19%), and urogenital disorders (7%). Key recommendations to reduce sow mortality included optimizing sow health and body condition, improving housing and feeding management, and addressing genetic factors. The study highlights the multifaceted nature of sow mortality and the importance of a comprehensive approach to mitigate risks and improve sow welfare and productivity.

This study aimed to evaluate the effects of dietary supplementation with 0.1% guanidinoacetic acid (GAA) in hyperprolific sows, from five days before farrowing until weaning, on farrowing kinetics, piglet metabolism, and pre-weaning performance. Twenty-three hybrid commercial sows (parity 2–4) were randomly assigned upon entry to the farrowing room to either a control diet (n = 11) or a control diet supplemented with 0.1% GAA (n = 12). Supplementation was provided from five days pre-farrowing until weaning (28 days). Litter size was standardized to 16 piglets per sow within 24 h of farrowing by cross-fostering excess piglets to nurse sows. Farrowing was closely monitored from the birth of the first piglet to the last. Piglets were individually weighed at birth, 24 h post-farrowing, and on d 14 and 28 (weaning). Colostrum, milk, and blood samples from sows and piglets were collected for targeted metabolite analysis. Colostrum samples were obtained within 1 h after the birth of the first piglet, while milk samples were collected on d 14 and at weaning. Blood samples from sows were taken pre-farrowing, 24 h post-farrowing, and on d 14 and 28 of lactation. Blood samples from piglets were collected 24 h after birth, on d 14, and at weaning. GAA supplementation significantly reduced farrowing duration (P < 0.05) in non-dystotic sows. Piglets born to GAA-supplemented sows exhibited greater weight gain from birth to 24 h (P < 0.05). However, these piglets were lighter (P < 0.05) at weaning compared to those from control sows, though they had a lower mortality rate (P < 0.05). GAA supplementation also influenced (P < 0.05) plasma amino acid and acylcarnitine profiles in both sows and piglets, with metabolic effects varying by physiological stage (prepartum, postpartum, early lactation, late lactation). These changes extended beyond the role of GAA as a precursor for creatine synthesis, impacting methylation capacity and amino acid sparing.

Based on observations in feral pigs, the role of dietary fibre and structure may be underestimated in suckling piglet nutrition. This study investigated the effect of grass hay offered to suckling piglets either separately or included in their creep feed, combined with nursery diets with or without grass pellet inclusion on growth performance and gastrointestinal development. Thirty-six litters (14–15 piglets per litter) were divided into three equal groups of 12 litters per treatment during the suckling phase: control group (CON) received regular creep feed; GH group received chopped grass hay as-is in separate feeders alongside regular creep feed; PGH group received regular creep feed but barley and wheat were replaced by 28

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important pathogens in pig production worldwide and responsible for enormous production and economic losses. PRRSV infection in gestating gilts and sows induces important reproductive failure. Additionally, respiratory distress is observed in infected piglets and fattening pigs, resulting in growth retardation and increased mortality. Importantly, PRRSV infection interferes with immunity in the respiratory tract, making PRRSV-infected pigs more susceptible to opportunistic secondary pathogens. Despite the availability of commercial PRRSV vaccines for more than three decades, control of the disease remains a frustrating and challenging task. This paper provides a comprehensive overview of PRRSV, covering its history, economic and scientific importance, and description of the viral structure and genetic diversity. It explores the virus’s pathogenesis, including cell tropism, viral entry, replication, stages of infection and epidemiology. It reviews the porcine innate and adaptative immune responses to comprehend the modulation mechanisms employed by PRRS for immune evasion.

Abstract Background Porcine ear necrosis (PEN) is characterized by dry crusts on the ear tip. The crusts often progress to moist and bloody lesions and may lead to partial loss of the ear tissue. The cause and pathophysiology of PEN are unknown. Skin infections, systemic infections, or ear biting have been suggested as a cause of PEN, but no proper evidence has been shown. The behavioural factor has not yet been investigated, therefore this study evaluated the importance of oral manipulations in the occurrence of PEN in nursery pigs. Three farms affected by PEN were visited weekly, and the prevalence and severity were recorded. Video recordings of the animals were performed, and the behaviour was evaluated. The presence of pathogens in the lesions and histological alterations were also analysed. Results The highest percentage of pigs with PEN lesions in the farms ranged between 58 and 93%, with most lesions being of mild to moderate severity. The first ear lesions occurred about 1–2 weeks after an increase in the number of ear manipulations in the pens. The frequency of the ear manipulations clearly changed over time, and the number of oral ear manipulation behaviour significantly differed (P < 0.05) between pigs in pens with high and low PEN prevalence. Increased ear manipulation behaviour was significantly related to a subsequent increase in PEN lesions (OR = 4.3; P < 0.001). Metagenomic investigation of lesion scrapings revealed a variety of pathogens mostly with low abundance, where microscopic alterations were found mainly in the epidermis. Conclusions Oral manipulation of the ear pinnae by pen mates was followed by the development of PEN lesions one to two weeks later. This suggests that the behaviour played an important role in the PEN lesions formation in the nursery pigs of the three farms. Bacteria found in PEN lesions most probably were secondary to initial external skin damage, but their relevance needs to be investigated further.

This study investigated the role of causative infectious agents in ulceration of the non-glandular part of the porcine stomach ( pars oesophagea ). In total, 150 stomachs from slaughter pigs were included, 75 from pigs that received a meal feed, 75 from pigs that received an equivalent pelleted feed with a smaller particle size. The pars oesophagea was macroscopically examined after slaughter. (q)PCR assays for H. suis , F. gastrosuis and H. pylori -like organisms were performed, as well as 16S rRNA sequencing for pars oesophagea microbiome analyses. All 150 pig stomachs showed lesions. F. gastrosuis was detected in 115 cases (77%) and H. suis in 117 cases (78%), with 92 cases (61%) of co-infection; H. pylori -like organisms were detected in one case. Higher infectious loads of H. suis increased the odds of severe gastric lesions (OR = 1.14, p = 0.038), while the presence of H. suis infection in the pyloric gland zone increased the probability of pars oesophageal erosions [16.4% (95% CI 0.6–32.2%)]. The causal effect of H. suis was mediated by decreased pars oesophageal microbiome diversity [−1.9% (95% CI − 5.0–1.2%)], increased abundances of Veillonella and Campylobacter spp., and decreased abundances of Lactobacillus , Escherichia-Shigella , and Enterobacteriaceae spp. Higher infectious loads of F. gastrosuis in the pars oesophagea decreased the odds of severe gastric lesions (OR = 0.8, p = 0.0014). Feed pelleting had no significant impact on the prevalence of severe gastric lesions (OR = 1.72, p = 0.28). H. suis infections are a risk factor for ulceration of the porcine pars oesophagea , probably mediated through alterations in pars oesophageal microbiome diversity and composition.

The microbiome of the reproductive tract is an area of research in full development. Specifically, the microbiome may be involved in reproductive health, disease, and pregnancy outcomes, as has been shown in humans and animals, including dogs. The aim of the present review was to summarize current knowledge on the microbiome of the canine reproductive tract, to expose the controversial role that some bacterial agents may play in canine subfertility, and to highlight future research perspectives.This review discussed whether the use of antimicrobials in dogs is appropriate to increase reproductive performance and to treat subfertility without proper diagnosis, and the possible use of probiotics to modulate the reproductive canine microbiome. Finally, we indicate areas in which scientific knowledge is currently lacking, and could be promising directions for future research.

As climate change intensifies, heat stress mitigation for pigs becomes more important. Trials involving induced heat waves are useful to test several measures (e.g. reduced stocking density) at a faster rate, but only when accurately evaluated and validated. In the present study we investigated the suitability of an artificial heating protocol at different pig weights (experiment 1). The impact of different stocking densities on fattening pigs during an artificial heat wave (experiment 2) was also investigated. Experiment 1: Forty 20-week-old pigs weighing 96.5±7.3kg (W100) and forty 17-week-old pigs weighing 72.7±9.9 kg (W70) were housed in two compartments. An artificial heat wave (heat load) was induced for three days. During 3-day periods before, during and after the heat load, physiological parameters (respiration rate (RR), rectal temperature (Trectal), skin temperature (Tskin) and behavior) were measured and average daily feed intake was observed. Ambient temperature, relative humidity and temperature-humidity index (THI) were monitored. Experiment 2: 150 fattening pigs were randomly divided into three treatment groups: SD1.3 (1.3m2/pig), SD1.0 (1.0m2/pig) and SD0.8 (0.8m2/pig). All pens had a total pen surface of 4.88 m2, corresponding with 4, 5 and 6 fattening pigs in the SD1.3, SD1.0 and SD0.8 groups, respectively. The heat load was induced for seven days on week 21. Respiration rate and Trectal were observed as in experiment 1. Average daily gain and average daily feed intake were also noted. During the heat load, THI reached ≥75 (78.4 (experiment 1) and 78.6 (experiment 2)), even when relative humidity decreased to ±45%. Every physiological parameter showed significant increases during the heat load. The prolonged heating protocol in experiment 2 also provoked significant decreases in average daily feed intake (15%) and average daily gain (19%) for all groups. Weight within the studied range of 70-100 kg did not have a significant impact on any of the parameters. However, Tskin was affected by both weight and heat load (P<0.05), where Tskin from W100 was always lower in comparison to W70. In addition, we found that 0.8m2/pig doubled the increase of Trectal during the heat load, namely SD0.8 (0.22°C) compared to SD1.0 (0.12°C) (P=0.033) and SD1.3 (0.13°C) (P=0.053). This suggests that pigs housed at higher densities are less able to regulate their internal heat production. However, RR and performances was not significantly affected by heat load in this experimental set-up. A stocking density of 1.0 m2/animal may be sufficient to mitigate some negative effects of heat stress.

Weaning is one of the most important stress events in the life of pigs, increasing the risk for health problems and reduced performance. The release of pheromones in pig stables can be considered an environmental enrichment and alleviate the negative effects of weaning stress in nursery pigs. The present study investigated the effect of synthetic pheromones on the performance of nursery pigs. The effect of positive handling of sows in the farrowing house on the performance of the offspring in the nursery was also investigated. The study was performed in a commercial pig farm and included 24 batches of weaned piglets (216 piglets per batch). Half of the batches originated from sows exposed to positive handling. This implied that music was played from 6.00 a.m. to 6.00 p.m. from the moment the sows entered the farrowing house until weaning and that they were subjected to backscratching from the day they entered the farrowing unit the day of farrowing. During the nursery period, half of the batches were treated, and half served as controls. Piglets of treated groups were exposed to a synthetic analog of the maternal pig appeasing pheromone (PAP) (SecurePig®, Signs, Avignon, France). The product consisted of a gel block from which the pheromones were slowly released into the room. Different performance parameters were measured during the nursery period. Neither the sow treatment nor the treatment with pheromones significantly influenced the performance of the piglets during the nursery period (p > 0.05). The median values (95% confidence interval) of average daily gain, namely 318 (282–338) vs. 305 (272–322) g/day, feed conversion ratio, namely 1.64 (1.51–1.71) vs. 1.70 (1.57–1.75), and number of antimicrobial treatment days, namely 16.9 (9.6–25.0) vs. 17.3 (9.5–25.0) days, were numerically better in the nursery pigs exposed to the pheromones compared to the control groups. Mortality however was numerically higher in the treated groups, namely 4.4 (2.8–6.8) vs. 3.2 (0.9–4.2)%. Under the conditions of the present production system, pigs exposed to the pheromone treatment during the nursery did not show a significant performance increase.

BACKGROUND:Mycoplasma (M.) hyopneumoniae is associated with respiratory disease in pigs and is the primary agent of enzootic pneumonia. Quantification of M. hyopneumoniae-related outcome parameters can be difficult, expensive, and time-consuming, in both research and field settings. In addition to well-established methods, technological tools are becoming available to monitor various aspects of relevant animal- and environment-related features, often in real-time. Therefore, this study aimed to assess whether certain parameters, such as animal movement and body temperature using microchips (IMT), correlate with established parameters and whether the currently used parameters can be rationalized. RESULTS:The percentage of movement was significantly reduced by M. hyopneumoniae infection in pigs (p < 0.05), where the M. hyopneumoniae-infected group showed a lower percentage of movement (1.9%) when compared to the negative control group (6.9%). On the other hand, macroscopic (MLCL) and microscopic (MLL) lung lesions, respiratory disease score (RDS), M. hyopneumoniae-DNA load, and anti-M. hyopneumoniae antibody levels increased significantly in the M. hyopneumoniae-infected group 28 days post-inoculation (p < 0.05). Moderate (r > 0.30) to very strong correlations (> 0.80) were observed between the abovementioned parameters (p < 0.05), except for IMT. A significant and moderate correlation was reported between IMT and rectal temperature (r = 0.49; p < 0.05). Last, the average daily weight gain and the percentage of air in the lung were not affected by M. hyopneumoniae infection (p > 0.05). CONCLUSIONS:M. hyopneumoniae infection significantly reduced the movement of piglets and increased lung lesions, M. hyopneumoniae-DNA load, and anti-M. hyopneumoniae antibody levels; and, good correlations were observed between most parameters, indicating a direct relationship between them. Thus, we suggest that changes in movement might be a reliable indicator of M. hyopneumoniae infection in pigs, and that a selected group of parameters-specifically RDS, MLCL, MLL, M. hyopneumoniae-DNA load, anti-M. hyopneumoniae antibody levels, and movement-are optimal to assess M. hyopneumoniae infection under experimental conditions.