Porcine Health Management最新文献

Background: Porcine reproductive and respiratory syndrome virus (PRRSV) has significant productivity and economic impacts in swine herds. Accurately determining the PRRSV status at the herd level is crucial for producers and veterinarians to implement strategies to control and eliminate the virus from infected herds. This study collected oropharyngeal swabs (OSs), nasal swabs (NSs), oral fluid swabs (OFs), rectal swabs (RSs), and serum samples continuously from PRRSV challenged pigs under experimental conditions and growing pigs under field conditions. Additionally, OSs and serum samples were collected from individual sows from 50 large-scale breeding farms, and the collection of OSs does not require the sows to be restrained. Ct values of PRRSV were detected in all samples using real-time reverse transcriptase-polymerase chain reaction (RT-qPCR).

Results: In PRRSV challenged pigs, OSs showed a higher PRRSV-positive rate until the end of the observation period. The Ct values of OSs were significantly lower than those of NSs, OFs, and RSs at 2, 8, 12, 14 and 20 days post-challenge (DPC) (P < 0.05). For growing pigs, the positivity rate of PRRSV in OSs was higher than that in other sample types at 30, 70, and 110 days of age. In sows, 24,718 OSs and 6259 serum samples were collected, with PRRSV-positive rate in OSs (9.4%) being significantly higher than in serum (4.1%) (P < 0.05). However, the Ct values of PRRSV RNA in serum were significantly lower than those in OSs (P < 0.001).

Conclusions: The OSs sample type yielded higher PRRSV-positive rates for longer periods compared to NSs, RSs, OFs and serum samples for PRRSV detection in infected pigs. Therefore, OSs has a good potential to be a convenient, practical, and reliable sample type for implementing mass sampling and testing of PRRSV in large-scale pig farms.

Background: Lawsonia intracellularis is the causative agent of Porcine Proliferative Enteropathy (PPE), one of the most prevalent pig enteric diseases worldwide, but with sparse information about early infections in suckling piglets in the epidemiology of PPE. With that aim, this study evaluates the prevalence of L. intracellularis in 3-week-old piglets by analysing ileal digesta content and mucosal scrapings from 383 pigs from 16 farms (aprox., 25 pigs/batch) by real-time qPCR and droplet digital PCR (ddPCR).

Results: Forty-nine samples yielded a qPCR positive result. Eleven samples from eight farms were confirmed as positive with concentrations of L. intracellularis from 3.5 log₁₀ to 4.5 log₁₀ bacteria/g of sample. Another 16 samples, eight farms, were classified as low positive (2.07-2.38 log₁₀ bacteria/g) and 22 provided an uncertain result. Finally, 334 samples tested negative for L. intracellularis. At batch level, half of the farms included in the study had at least one positive sample and in 10 farms (62.5%) there was at least one low positive sample. The ddPCR was run in 50 of the 383 samples based on their PCR output (including low positive, uncertain and negative samples). Correlation analyses revealed a strong association between qPCR and the ddPCR results (ρ = 0.75; p < 0.001). The ddPCR allowed us to detect and confirm a positive result in the 19 samples classified as uncertain by the qPCR and detect L. intracellularis in 8 of 15 negatives by qPCR.

Conclusions: The results of the study demonstrate that a number of piglets are already infected with L. intracellularis during the suckling period evidencing early infection in certain animals, adding information of PPE epidemiology and opening new research topics such as sow-piglet transmission. Study results also evidence the usefulness of a combination of qPCR and ddPCR to improve qPCR sensitivity but assuring high specificity.

Background: A Tonsil-Oral-Scrubbing (TOSc) method was developed to sample the sow's oropharyngeal and tonsillar area without snaring and has shown comparable porcine reproductive and respiratory syndrome virus (PRRSV) RNA detection rates with tonsil scraping in infected sows. This study investigated the effect of specific TOSc collection factors on the PRRSV RT-rtPCR results (detection rates and Ct values). Those factors include whether the sow was snared or not snared at TOSc collection ("snared" vs. "not snared"); whether the sow was laying down or standing at collection ("laying down" vs. "standing"); and type of collectors used for TOSc collection ("TOSc prototype" vs. "Spiral-headed AI catheter (SHAC)"). Volume of fluid was compared between "snared" and "not snared" groups, and collection time was compared between "laying down" and "standing" groups as well.

Results: The effect for each factor was assessed in three independent studies following the same design: TOSc was collected twice from each studied sow, once with the baseline level for a factor ("not snared", or "standing", or "TOSc prototype"), and another time followed by the other level of the paired factor ("snared", "laying down", or "SHAC", correspondingly). Results showed that "not snared" TOSc had numerically higher PRRSV RNA detection rate (60.7% vs. 52.5%, p = 0.11), significantly lower median Ct values (31.9 vs. 32.3, p < 0.01), and significantly higher volume of fluid than "snared" samples (1.8 mL vs. 1.2 mL, p < 0.01); "laying down" TOSc samples did not differ statistically (60.7% vs. 60.7%) in the PRRSV RNA detection rate, obtained numerically lower median Ct values (30.9 vs. 31.3, p = 0.19), but took 40% less collection time compared to "standing" TOSc samples; samples collected using the "TOSc prototype" had numerically higher PRRSV RNA detection rate (91.7% vs. 88.3%, p = 0.27) and significantly lower median Ct values (32.8 vs. 34.5, p < 0.01) than that from "SHAC".

Conclusions: Under the conditions of this study best practices for TOSc collection aiming higher detection rate of PRRSV RNA while minimizing time for collection were suggested to be sampling TOSc without snaring, when sows are laying down, and using a prototype TOSc collector.

Background: Within the last decades industrial swine herds in Europe grown significantly, creating an optimized reservoir for swine influenza A viruses (swIAV) to become enzootic, particularly in piglet producing herds among newborn, partly immunologically naïve piglets. To date, the only specific control measure to protect piglets from swIAV is the vaccination of sows, which provides passive immunity through maternally derived antibodies in colostrum of vaccinated sows. Interruption of infection chains through management practices have had limited success. This study focused on weaned piglets in five enzootically swIAV infected swine herds in North-West and North-East Germany and aimed to better understand swIAV infection patterns to improve piglet protection and reduce zoonotic risks. Participating farms fulfilled the following inclusion criteria: sow herd with ≥ 400 sows (actual size 600-1850 sows), piglets not vaccinated against influenza A virus and a history of recurrent respiratory problems associated with continuing influenza A virus infection. Influenza vaccination was performed in all sow herds, except for one, which discontinued vaccination during the study.

Results: First swIAV detections in weaned piglets occurred at 4 weeks of age in the nursery and continued to be detected in piglets up to 10 weeks of age showing enzootic swIAV infections in all herds over the entire nursery period. This included simultaneous circulation of two subtypes in a herd and co-infection with two subtypes in individual animals. Evidence for prolonged (at least 13 days) shedding was obtained in one piglet based on two consecutive swIAV positive samplings. Possible re-infection was suspected in twelve piglets based on three samplings, the second of which was swIAV negative in contrast to the first and third sampling which were swIAV positive. However, swIAV was not detected in nasal swabs from either suckling piglets or sows in the first week after farrowing.

Conclusions: Predominantly, weaned piglets were infected. There was no evidence of transmission from sow to piglet based on swIAV negative nasal swabs from sows and suckling piglets. Prolonged virus shedding by individual piglets as well as the co-circulation of different swIAV subtypes in a group or even individuals emphasize the potential of swIAV to increase genetic (and potentially phenotypic) variation and the need to continue close monitoring. Understanding the dynamics of swIAV infections in enzootically infected herds has the overall goal of improving protection to reduce economic losses due to swIAV-related disease and consequently to advance animal health and well-being.

Background: The administration of a gonadotropin releasing factor (GnRF) analog to pigs has proven to induce antibodies against endogenous GnRF. In gilts (young female pigs), the subsequent blocking of GnRF activity by specific antibodies results in a temporary suppression of ovarian activity and sexual maturation. One pre-clinical and two clinical studies were conducted to assess the ability of the GnRF analog to produce immunologically suppression of the ovarian function, preventing gilts from reaching puberty before harvest, at 27 weeks of age.

Results: In the three studies, a significant reduction of size and weight of reproductive organs and gilts in oestrus was demonstrated in vaccinated gilts compared with intact gilts. A significant increase in anti-GnRF antibody levels in sera was observed after the 2nd dose, which lasted until the end of the study in each of the protocols used. Progesterone levels were significantly reduced from 6 to 8 weeks after 2nd vaccination in clinical studies 2 and 1 respectively, and from 6 weeks after 2nd vaccination in the pre-clinical study. Estradiol levels were below the limit of detection for clinical study 2 and significantly reduced in vaccinated gilts at the end of the pre-clinical study and the clinical study 1.

Conclusions: Vaccination of gilts with a GnRF analog with two different protocols (1st dose from 10 to 14 weeks of age, and a 2nd dose 8 or 4 weeks later) was effective in reducing the development of puberty for at least 9 weeks post 2nd dose. These results confirm the flexibility of vaccination programs for veterinarians and producers which can be adapted to pig management practices in commercial farms.

Background: During the fall of 2020, the porcine reproductive and respiratory syndrome virus (PRRSV) L1C.5 variant emerged and rapidly spread throughout southern Minnesota generating questions regarding possible transmission routes. This study aimed to investigate whether PRRSV could be detected on surfaces inside and outside pig barns housing L1C.5 variant PRRSV-positive pigs to illustrate the potential for indirect transmission of PRRSV. Seven Midwestern U.S. PPRS-positive breeding or growing pig farms and one PRRS-negative farm were conveniently selected. Internal and external barn surfaces were wiped using a PBS moistened cloth and the resulting liquid was submitted to the University of Minnesota Veterinary Diagnostic Laboratory for PRRSV RT-PCR testing and virus isolation.

Results: All (n = 26) samples from PRRSV-negative farm tested negative. Nineteen (13%) out of 143 samples from positive farms yielded positive RT-PCR results. Positive samples originated primarily from exhaust fan cones and doorknobs, followed by anteroom floor and mortality carts/sleds. Virus isolation attempted on two samples did not yield positive results.

Conclusions: PRRSV contamination can occur on surfaces inside and outside pig barns that are in frequent contact with farm personnel. Although virus isolation attempts were negative, our results illustrate the potential for PRRSV to be transmitted indirectly through contaminated materials or farm personnel. The study supports the implementation of biosecurity practices by farm personnel to prevent the introduction of PRRSV into farms and the prevention of PRRSV transmission between farms.

Background: Porcine Epidemic Diarrhea (PED) is a highly contagious disease caused by Porcine Epidemic Diarrhea Virus (PEDV), resulting in a mortality rate of suckling piglets as high as 100%. Vaccination is the primary strategy for controlling PEDV infection, however, there is currently a lack of reliable methods for assessing the efficacy of vaccination. This study aimed to analyze serum and colostrum samples from 75 parturient sows with a specific vaccination strategy to measure levels of IgG, IgA, and neutralizing antibodies (nAbs) against PEDV, and to investigate the correlation between serum and colostrum antibody levels, as well as to identify potential biomarkers that can be used to evaluate immunization effects under field conditions.

Results: The findings of correlation analysis between antibody levels of IgA, IgG, and nAbs in serum or colostrum samples revealed that IgG demonstrated the most robust correlation with nAbs exhibiting a correlation coefficient of 0.64 in serum samples. Conversely, IgA exhibited the highest correlation with nAbs, with a correlation coefficient of 0.47 in colostrum samples. Additionally, the correlation analysis of antibody levels between serum and colostrum samples indicated that serum IgA displayed the strongest correlation with colostrum IgA, with a coefficient of 0.63, indicating that serum IgA may serve as a viable alternative indicator for evaluating IgA levels in colostrum samples. To further evaluate the suitability of serum IgA as a substitute marker for colostrum IgA, levels of IgA antibodies in serum samples from sows were examined both pre- and post-parturition. The findings indicated that serum IgA levels were initially low prior to the initial immunization, experienced a notable rise 21 days after immunization, and maintained a significant elevation compared to pre-immunization levels from 21 days pre-parturition to 14 days postpartum, spanning a total of 35 days.

Conclusions: Serum anti-PEDV IgA antibody levels may serve as a valuable predictor for immunization effects, allowing for the assessment of colostrum IgA antibody levels up to 21 days in advance. This insight could enable veterinarians to timely adjust or optimize immunization strategies prior to parturition, thereby ensuring adequate passive immunity is conferred to piglets through colostral transfer postpartum.

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.

Background: The immunocrit is a cost-effective and straightforward technique traditionally used to assess passive immunity transfer to newborn piglets. However, it has not been previously used for monitoring the effect of vaccination and/or infections. Therefore, this study aimed to evaluate the usefulness of the immunocrit technique as an immunological monitoring tool in a vaccination and challenge scenario, using porcine circovirus 2 (PCV-2) as pathogen model. The immunocrit ratio was monitored in PCV-2 vaccinated (V) and non-vaccinated (NV) 3-week-old piglets (study day 0, SD0) that were subsequently challenged with this virus at SD21 and followed up to SD42. Additional techniques (PCV-2 IgG ELISA, optical refractometry, and proteinogram) were performed to further characterize the results of the immunocrit analysis.

Results: Immunocrit, γ-globulin concentration and PCV-2 S/P values followed similar dynamics: descending after PCV-2 vaccination but ascending after an experimental PCV-2 inoculation. However, statistically significant differences between V and NV animals were only found with the PCV-2 ELISA. In this case, V animals had significantly higher (p < 0.05) S/P values (S/P ratio = 0.74) than NV (S/P ratio = 0.39) pigs only after challenge at SD42. On the other hand, serum total protein obtained by refractometer (STPr) were maintained from SD0 to SD21 and increased in both groups from SD21 to SD42. Correlations between techniques were low to moderate, being the most robust ones found between immunocrit and optical refractometry (ρ = 0.41) and immunocrit with γ-globulins (ρ = 0.39). In a subset of sera, the proteinogram technique was applied to the whole serum and the supernatant of the immunocrit, with the objective to characterize indirectly the immunocrit fraction. The latter one included all protein types detectable through the proteinogram, with percentages varying between 64.3% (γ-globulins) and 82% (β-globulins).

Conclusion: The immunocrit technique represented a fraction of the total serum proteins, with low to moderate correlation with all the complementary techniques measured in this study. Its determination at different time points did not allow monitoring the effect of vaccination and/or infection using PCV-2 as a pathogen model.