Alternatives to zinc oxide in pig production.

Zinc oxide (ZnO) has been applied for many years in the production of pigs to reduce the number of diarrhoea in weaned piglets. In June 2022, the European Union banned the use of zinc oxide (ZnO) in pig feed. According to scientific reports, the may reason was the accumulation of this microelement in the environment of pig production. It has been shown that frequent application of ZnO can lead to increased antibiotic resistance in pathogenic swine microflora. The main alternatives to ZnO are probiotics, prebiotics, organic acids, essential oils, and liquid feeding systems. Alternatives to ZnO can be successfully used in pig production to reduce the number of diarrhoea among piglets during the postweaning period. Additional reports indicated that bacteriophage supplementation has a positive effect on the health of pigs. The article provides an overview of current ZnO substitutes that can be used in pig farming.

The effects of lack of movement in sows during pregnancy period on cortisol, acute phase proteins and lymphocytes proliferation level in piglets in early postnatal period.

Prolonged exposure to stress may cause adverse effects on animal physiology. It is especially important during the gestation period as female physiology can affect the unborn offspring in the form of prenatal stress. Intensive pig farming industry developed gestation crates that enable to keep sows during gestation period in small stalls which do not allow animals to move freely for a maximum of 4 weeks after successful insemination (Council Directive 2008/120/EC). Although these crates have production advantages, many health and welfare issues have been raised recently. In this study we tested to what extent the lack of movement of sows kept in the gestation crates had an impact on some blood and saliva constituents of new-born piglets. In total, the samples were collected from 80 piglets when they were 3, 7 and 21 days of age and tested for cortisol levels in blood and saliva, acute phase proteins (amyloid A, C-reactive protein, haptoglobin) and lymphocytes proliferation index (in response to ConA, PHA and PWM). 40 piglets were from sows kept in free movement housing (FM group) from day 1 to day 100 of pregnancy and forty piglets were from sows in the movement restriction group (MR), in which the sows were kept in crates just allowing them to stand up and lie down from day 1 to day 100 of the pregnancy (research was conducted before the implementation Directive 2008/120/EC i.e. January 1,2013). The results of the study showed that the piglets delivered by sows kept under movement restriction conditions exhibited higher cortisol and acute phase protein levels as well as a lower lymphocytes proliferation index. This suggests that lack of movement in sows during the gestation period influences piglets' physiology and indicates that the piglets are suffering from prenatal stress caused by insufficient housing conditions of their mothers potentially leading to poor health and welfare of their offspring.

Four years of African swine fever in Poland. New insights into epidemiology and prognosis of future disease spread.

Four and a half years of African Swine Fever (ASF) in population of free-ranging wild boars and domestic pigs revealed a number of novel insights into the disease epidemiology. Until No- vember 20th, 2018, in total 3048 cases in wild boars and 213 outbreaks in domestic pigs have been confirmed. In spite of low contagiosity as well as low rate of ASF spread in wild boars the disease has an enormous socio-economical impact on the production of pigs in Poland. One of the most important aspects which directly influences the dynamics of ASF spread is the unpredictable hu- man activity. Another important factor responsible for continuous ASF spread is fast recovery of wild boar population in spite of efforts taken by hunters. Assuming our scientific opinion ASF seems to be present in wildlife for the incoming few or several years. Therefore, extraordinary measures should be prepared and undertaken to limit the risk of the occurrence of future out- breaks in domestic pigs. One of the most crucial issues is implementation of strict biosecurity measures in all domestic pigs holdings.

Effects of amoxicillin, ceftiofur, doxycycline, tiamulin and tulathromycin on pig humoral immune responses induced by erysipelas vaccination.

It addition to their antimicrobial properties, antibiotics can influence the host immune system (modulation of cytokine secretion, antibody production and T-cell proliferation). In the present study, the authors studied the effects of therapeutic doses of amoxicillin (AMX), ceftiofur (CEF), doxycycline (DOXY), tiamulin (TIAM) and tulathromycin (TUL) on the postvaccinal immune response after pigs had been vaccinated against erysipelas. Because humoral immunity is considered as the most important in the protection against swine erysipelas, the present study focused on the interactions between antibiotics and postvaccinal humoral immunity. One hundred and five, eight-week-old pigs of both sexes were used. Specific antibodies to the Erysipelothrix rhusiopathiae antigen were determined using a commercial ELISA test. In pigs treated with DOXY or CEF or TIAM, a significant reduction in the number of positive pigs was observed four and six weeks after the second dose of vaccine, compared with the remaining vaccinated groups. In pigs treated with CEF, the ELISA score was significantly lower than in non-treated vaccinated pigs. While in vaccinated pigs treated with AMX or TUL, the ELISA score was significantly higher than in pigs treated with the remaining antibiotics and than in non-treated vaccinated controls. The results of the present study indicate that vaccination of pigs against erysipelas in the presence of antibiotics may result in a decrease (CEF, DOXY, TIAM) or enhancement (AMX, TUL) in the production of specific antibodies.

Development of cross-priming amplification for direct detection of the African Swine Fever Virus, in pig and wild boar blood and sera samples.

UNLABELLED: African swine fever (ASF) is considered a major threat to the production of pigs worldwide. The ASF aetiological agent, ASFV, is the sole member of the Asfivirus genus, belonging to the Asfarviridae family. An effective ASF vaccine is not currently available, thus the only measures of ASF spread control include, reliable and fast diagnosis. Officially approved, diagnostic methods include, virus isolation, serological assays, including enzyme-linked immunosorbent assay and immunoperoxidase assay (IPT) and different modifications of the polymerase chain reaction (PCR). This paper describes the first development and application of a cross-priming amplification method (CPA) for the direct detection of genetic ASFV material, in blood and sera from pigs and wild boars. This method is specific only to ASFV DNA. The study showed that CPA had equal sensitivity, in comparison to the official, universal probe library (UPL) real-time PCR and reached 7·2 copies of standard plasmid DNA, containing a p72 gene fragment. This method was capable of detecting ASFV DNA in all examined blood samples, originating from pigs; n = 10 and wild boars; n = 76. The obtained results were also confirmed by the officially approved, real-time PCR. The developed CPA might be further used by local and county veterinary officers, hunters or pig farmers, for preliminary ASF diagnosis. SIGNIFICANCE AND IMPACT OF THE STUDY: The spread of the African swine fever virus (ASFV) among infected pigs and wild boars, is currently one of the most important facets of virus transmission in eastern Europe. Cross-priming amplification (CPA) has been developed, for fast and direct development of genetic ASFV material in the blood and sera of infected pigs and wild boars. It has been shown that CPA is a rapid, sensitive and specific isothermal method for the detection of ASFV DNA, in directly collected blood or sera from pigs and wild boars.

Prevalence and risk factors for Lawsonia intracellularis, Brachyspira hyodysenteriae and Salmonella spp. in finishing pigs in Polish farrow-to-finish swine herds.

The aim of the study was to estimate the herd-level, within-herd prevalence, the frequency of mixed infections and risk factors for L. intracellularis, B. hyodysenteriae and Salmonella spp. in selected farrow-to-finish Polish pig herds. A total of 254 pooled fecal samples were collected from 9 to 24 week-old pigs in 70 herds. Real time PCR for detection of L. intracellularis and B. hyodysenteriae was performed. For Salmonella spp. bacteriological examination was performed. The herd-level prevalences of L. intracellularis, B. hyodysenteriae and Salmonella spp. among examined herds were 65.7%, 1.4% and 8.6%, respectively. The within-herd prevalences (in positive herds) for L. intracellularis, B. hyodysenteriae and Salmonella spp. were 51.5%, 75.0% and 30.4%, respectively. All herds with diarrhea observed during sampling were infected with L. intracellularis and 60% of herds with no diarrhea at the moment of sampling were infected with L. intracellularis (p=0.035). In herds with more than 200 sows the prevalence of Salmonella spp. was significantly higher compared to herds with less than 200 sows (p=0.027). In herds where all-in/all-out (AIAO) was respected, prevalence of L. intracellularis was significantly lower than in herds where this rule was not kept (p=0.024). Obtained results confirm that L. intracellularis is the major cause of bacterial diarrhea in finishing pigs. The present study identified AIAO and herd size as a risk factor, at the herd level, for L. intracellularis and Salmonella spp., respectively.

Local and systemic immune response in pigs during subclinical and clinical swine influenza infection.

Local and systemic immune responses in pigs intranasally (IN) and intratracheally (IT) inoculated with swine influenza virus (SIV) were studied. No clinical signs were observed in IN-inoculated pigs, while IT-inoculated pigs developed typical signs of influenza. Significantly higher titres of specific antibodies and changes of haematological parameters were found only in IT-inoculated pigs. Because positive correlations between viral titre, local cytokine concentration, and lung pathology have been observed, we hypothesise that both viral load and the local secretion of cytokines play a role in the induction of lung lesions. It could be that a higher replication of SIV stimulates immune cells to secrete higher amounts of cytokines. The results of the present study indicate that pathogenesis of SIV is dependent on both, the damage caused to the lung parenchyma directly by virus, and the effects on the cells of the host's immune system.

Rapid detection of Chlamydia/Chlamydophila group in samples collected from swine herds with and without reproductive disorders.

The study was carried out in seven reproductive herds of pigs. In three of them reproductive disorders were observed. Three herds consisted of 10-50 and four consisted of 120-500 adult sows and they were called small and medium, respectively. Fifty-seven adult sows were randomly selected from herds. Serum samples were tested using the complement fixation test and swabs from both eyes and from the vaginal vestibule were examined using real-time PCR. All serum samples were negative. Infected sows were present in each of the study herds. In total, there were 28 positive samples (53%, 28/48) in real-time PCR in sows with reproductive disorders and 35 (53%, 35/66) in sows selected from herds without problems in reproduction. One isolate proved to be Chlamydophila pecorum, whereas all the remaining were Chamydia suis.

Molecular studies on pig cryptosporidiosis in Poland.

Cryptosporidium intestinal parasites have been detected in farmed pigs worldwide. Infections are usually asymptomatic with a low number of oocysts shed in pig feces. This makes the recognition of infection difficult or unsuccessful when microscopic methods are used. The aim of this study was molecular identification of Cryptosporidium species in pig herds raised in Poland with regard to the occurrence of zoonotic species. In total, 166 pig fecal samples were tested. The examined pigs were aged 1 to 20 weeks. Overall, 39 pig farms were monitored for parasite presence. The detection and identification of Cryptosporidium DNA was performed on the basis of PCR-RFLP and nucleotide sequence analysis of the amplified 18 SSU rRNA and COWP gene fragments. Infected animals were housed in 21 (53.8%) of the pig farms monitored. The presence of Cryptosporidum was confirmed in 46 (27.7%) samples of pig feces. Among positive fecal samples, 34 (29.3%) were collected from healthy animals, and 12 (24%) from diarrheic pigs. Most infected animals (42.1%) were 2 to 3 months old. The following parasite species were detected: C. scrofarum, C. suis and C. parvum. Indeed, asymptomatic infections caused by C. scrofarum were observed in the majority of the herds. Mixed infections caused by C. suis and C. scrofarum were not common; however, they were observed in 8.6% of the positive animals. C. parvum DNA was found only in one sample collected from a diarrheic pig. The application of molecular diagnostic tools allowed for detection and identification of Cryptosporidium species in pigs. The sporadic findings of C. parvum are subsequent evidence for the contribution of pigs in the transmission of cryptosporidiosis from animals to humans.

Epidemiology of African Swine Fever in Poland since the detection of the first case.

The purpose of this paper is to provide characteristics of the spread of African Swine Fever (ASF) in Poland from February to August, 2014. The samples from dead wild boar and domestic pigs were submitted to the National Veterinary Research Institute, National Reference Laboratory for ASF in Pulawy, Poland, for testing by PCR and ELISA methods. In the studied period, fourteen cases of ASF in wild boar and two outbreaks in backyard pigs were confirmed. In addition to the results of laboratory tests performed in 2014, the article describes the ASF surveillance programme in wild boar and pigs in Poland carried out in 2011-2013. The spread of ASF in Poland is compared with the epidemiological situation in Lithuania, Latvia, Belarus and the Russian Federation.

Effect of various husbandry conditions on the production parameters of swine herds in Poland.

The aim of this study was to collect production data of Polish swine herds, with special emphasis on the production parameters in farrow to finish pig herds. Another goal was to determine differences in the production performance of swine herds with different sizes, various status with regard to biosecurity, and with different veterinary expenditure. For this purpose, questionnaire surveys were carried out in 96 polish farrow to finish pig herds. The data concerning production parameters (e.g. the number of pigs born per sow per year, litters per sow per year, pre- and post-weaning mortality), farm size (small, medium, large), management (all in-all out by room or building), veterinary expenditure (including medication) and the percentage of pigs under medical treatment, were collected. The data obtained in the present study indicate that in general, the efficiency of swine production in evaluated farms was relatively low. It was also found that in large swine farms the efficiency was better than that in small ones and that the proper biosecurity positively influenced the performance of the swine farms. However, only in 10.4% facilities, the biosecurity rules and methods, including the principle "all-in all-out", were implemented and kept. It seems that inefficient swine production on the majority of Polish farms results from poor basic knowledge on pig production and understanding of fundamental economic rules of swine breeding.

Effects of antibiotics on acquired immunity in vivo--current state of knowledge.

Antibiotics are widely used in the therapy of infections. Besides the respective interactions between antibiotics and pathogens it seems that antibiotics also directly interact with the immune system. Some commonly used antibiotics are currently known to have effects on the innate immune response, as shown by in vitro, ex vivo and also in vivo animal experiments and clinical studies. Most of the experimental papers published to date, as well as most reviews, relate to how antibiotics affect the innate immune response or non-specific monocyte or lymphocyte proliferation. However the effects of antibiotics on the adaptive immune response are still not well characterized. This review of the literature considering different in vivo experiments indicate the real importance of interrelations existing between acquired immune responses and antibiotics, however, the mechanism of immunomodulatory effects of antibiotics are still poorly understood. Currently, data on the immunomodulating effects of antibiotics often remain heterogeneous, contradictory or insufficient, but most results published to date revealed the immunosuppressive effect of antibiotics on the antigen-specific immune response in vivo. In pigs as well as in poultry herds, it is not uncommon practice to add antibiotics to drinking water or feed at the time of vaccination. Information on the effects of such practices on the immune system of animals is restricted and more in vivo studies are needed to investigate the effects of antimicrobial drugs on the immune system, especially in the field conditions.

Antimicrobial susceptibility of Brachyspira hyodysenteriae isolated from 21 Polish farms.

Swine dysentery (SD) is a common disease among pigs worldwide, which contributes to major production losses. Antimicrobial susceptibility testing of B. hyodysenteriae, the etiological agent of SD, is mainly performed by the agar dilution method. This method has certain limitations due to difficulties in interpretation of results. The aim of this study was the analysis of antimicrobial susceptibility of Brachyspira hyodysenteriae (B. hyodysenteriae) Polish field isolates by broth microdilution procedure. The study was performed on 21 isolates of B. hyodysenteriae, collected between January 2006 to December 2010 from cases of swine dysentery. VetMIC Brachyspira panels with antimicrobial agents (tiamulin, valnemulin, doxycycline, lincomycin, tylosin and ampicillin) were used for susceptibility testing of B. hyodysenteriae. The minimal inhibitory concentration (MIC) was determined by the broth dilution procedure. The lowest antimicrobial activity was demonstrated for tylosin and lincomycin, with inhibition of bacterial growth using concentrations > 128 microg/ml and 32 microg/ml, respectively. In the case of doxycycline, the MIC values were < or = 2.0 microg/ml. No decreased susceptibility to tiamulin was found among the Polish isolates and MIC values for this antibiotic did not exceed 1.0 microg/ml. The results of the present study confirmed that Polish B. hyodysenteriae isolates were susceptible to the main antibiotics (tiamulin and valnemulin) used in treatment of swine dysentery. Further studies are necessary to evaluate a possible slow decrease in susceptibility to tiamulin and valnemulin of B. hyodysenteriae strains in Poland.

Application of real-time PCR for detection of Lawsonia intracellularis and Brachyspira hyodysenteriae in fecal samples from pigs.

The aim of the study was to develop and validate real-time PCR method for the quantification of Lawsonia intracellularis and Brachyspira hyodysenteriae in porcine feces. Before the optimization process was performed two different extraction methods were compared to select the more efficient one. Based on the results achieved at this stage the boiling procedure was rejected and a commercially available silica-membrane based method was chosen for further analysis. The primers and the Taqman probe for B. hyodysenteriae and L. intracellularis were based on the sequence of NADH oxidase gene and 16S rDNA gene, respectively. The detection limit of the real-time PCR for suspension of feces inoculated with B. hyodysenteriae and L. intracellularis was determined to be 1.5x10(3) CFU/ml and 6.5x10(1) CFU/ml, respectively. The results of this study demonstrate that our real-time PCR is able to detect low number of B. hyodysenteriae and L. intracellularis cells which is satisfying in routine diagnosis of swine dysentery and proliferative enteropathy. Therefore, it is possible to identify both subclinically infected pigs and those representing an acute form of mentioned diseases. In summary, the quantitative real-time PCR is useful for routine diagnosis of L. intracellularis and B. hyodysenteriae. Compared to conventional PCR, the new validated quantification method based on real-time PCR is fast and with reduced risk of laboratory contamination. The novel technique is specific and even more sensitive than the previously used one. Furthermore, the new real-time PCR enables quick detection and quantification of both pathogens in fecal samples, which helps to estimate the health status of a pig herd.

Reactivity of heat-stable Leptospira antigenic preparation used in enzyme-linked immunosorbent assay for detection of antibodies in swine serum.

Serology plays an important role in laboratory diagnosis of leptospirosis. Apart from the most often used microscopic agglutination test (MAT), enzyme-linked immunosorbent assay (ELISA) seems to be useful especially in screenings of animal herds. The ELISA used for detection of antibodies against selected Leptospira serogroups in swine serum samples was investigated during the study. An essential element of this test is heat-stable antigenic preparation from cultures of Leptospira interrogans serovars Icterohaemorrhagiae, Pomona and L. borgpetersenii serovar Sejroe. The aim of the present study was to identify and analyze ELISA heat-stable antigen fractions playing a role in the reaction with leptospiral antibodies indicated in swine serum. Reactivity of the three-component antigenic preparation was compared in immunoblotting with reactivity of six heat-stable antigenic preparations made from the following single serovars: L. interrogans serovars Icterohaemorrhagiae, Pomona, Canicola, L. borgpetersenii serovars Sejroe, Tarassovi and L. kirshneri serovar Grippotyphosa. All antigenic preparations were submitted to SDS-PAGE and transferred to a nitrocellulose membrane using a semidry system. After the transfer, the membrane was incubated with diluted swine serum containing antibodies specific for one of the six above mentioned Leptospira serovars. For the three-component antigenic preparation and antigens prepared from single serovars the immunoblot revealed reaction of sera with fractions of the 20-26 kDa region and around the 14.5 kDa region. The investigated heat-stable Leptospira antigenic preparation contains fractions demonstrating serogroup- and species-specificity. Fraction 20-26 kDa showed serogroup-specific activity, whereas the fraction around 14.5 kDa showed species-specific activity.

Influence of long-term vaccination of a breeding herd of pigs against PCV2 on reproductive parameters.

The objective of the study was to evaluate an efficacy of sows vaccination protocols in the herd with serious problems affecting efficacy of reproduction. The study was performed in a large pig herd with about 1200 sows. Before vaccination against PCV2, farrowing rate in this farm was about 65%. Sows, boar and replacement gilts were immunized using Circovac vaccine (Merial, France) according to producer's recommendations. Parameters of production were analyzed since 2007 until 2010 in selected batches of sows inseminated at the same weeks of the year (17th, 18th, 19th and 20th) to eliminate seasonal variability. In total, 940 sows were subjected to the study. No significant changes in management during these years were introduced. The applied protocol of sow herd long-term vaccination proved to be very efficient. All measured production parameters: reproduction rate, number of piglets born alive, birth weight of piglets and number of piglets weaned per a litter improved after implementation of immunization program. Moreover, further improvement was observed with vaccination in the following reproduction cycles. The most spectacular effect of vaccination regarded average farrowing rate that increased from 64.76% in control group to 86.93% after basic vaccination. Two years after implementation of vaccination program this parameter reached 93.6%. Number of piglets weaned per sow per a litter improved from 10.31 to 11.74 after one year of vaccination and remained relatively stable through the following year. Simultaneously, the percentage of newborn piglets with birth weight < 1 kg decreased significantly (p < 0.05). To summarize, vaccination against PCV2 influenced positively the insemination rate, number of piglets born alive and weaned per litter as well as birth body weight and percentage of piglets weighing < 1 kg.

Comparison of PCR methods for detection of classical swine fever virus and other pestiviruses.

Classical swine fever (CSF) is a notifiable, highly contagious disease of swine controlled mainly with costly administrative methods. Swine may be infected not only with classical swine fever virus (CSFV), but also with other, non porcine, genetically and antigenically related pestiviruses. Differentiation of infections with CSFV and other pestiviruses is a crucial element of diagnostics. In the present study two real-time PCR methods and conventional one-tube nested PCR for specific detection of CSFV were compared. Additionally, two methods designed for detection of all pestivirus species real-time SYBR Green I and one-tube nested PCR were included into the study. Analyzed methods varied considerably regarding their sensitivity and specificity, what suggests that careful selection of diagnostic methods and their evaluation on a regular basis is necessary.

Linked outbreaks and control of porcine reproductive and respiratory syndrome and postweaning multisystemic wasting syndrome in a pig farm in Poland.

In a newly established farrow-to-finish farm (porcine reproductive and respiratory virus [PRRSV]-free, porcine circovirus type 2 [PCV-2]-infected), reproductive failure was seen seven months after population. The conception rate dropped from 89 to 51 per cent, and the abortion rate increased from 0.5 to 11 per cent. The following month, characteristic lesions of postweaning multisystemic wasting syndrome (PMWS) and elevated mortality were observed in weaned pigs. Laboratory examinations confirmed reproductive failure due to PRRSV and PMWS associated with apparent activation of the PCV-2 circulating in the farm. The herd was closed for replacement and a number of measures to improve hygiene, environmental conditions and feeding were applied. The abortion rate returned to preoutbreak levels four months after the beginning of the PRRS outbreak and the conception rate returned to normal four months later. Slower improvement was observed regarding the PMWS outbreak, with PMWS-related losses disappearing nine months after the detection of PMWS. Analysis of seroconversion profiles to PCV-2 and PRRSV during the outbreak and after its control indicated that while PRRSV was eliminated from sows and weaners by the control measures, the time of PCV-2 infection was unchanged and occurred at seven weeks of age during the PMWS outbreak as well as after its elimination. However, the elimination of PMWS from the herd coincided with increased levels of maternally derived antibodies to PCV-2 in one- to five-week-old pigs and faster serological responses to infection with PCV-2.

Usefulness of PCR/RFLP and ERIC PCR techniques for epidemiological study of Haemophilus parasuis infections in pigs.

Haemophilus parasuis belongs to opportunistic microorganisms of undefined virulence. The purpose of the studies was to compare suitability of PCR/RFLP in our modification and ERIC PCR for epidemiological study of domestic strains of H. parasuis. The results were evaluated taking into account two different aspects: suitability of the tests for isolating the highest possible number of clone groups and subjective evaluation of the method judged with respect to the following criteria: difficulty, availability of equipment and reagents as well as time and cost of the study. The results obtained in the present study show that the two methods used for typing of H. parasuis had high discriminatory power. Taking into account this parameter it can be concluded that ERIC PCR is more suitable than PCR/RFLP. This justifies the use of ERIC PCR for routine epidemiological analyses of mentioned pathogen. Taking into account the complexity of method used, ERIC-PCR based on random amplification of DNA, proved to be comparable to PCR/RFLP. The last mentioned technique is relatively less expensive and labour-consuming, especially when diagnostic PCR method is used for the epidemiological studies.