In this study, we propose a possible way of obtaining reproductive and respiratory syndrome virus (PRRSV) free offspring from genetically valuable lines of Přeštice black-pied boars com- ming from PRRSV-positive pig breeding herds with the use of artificial insemination (AI). The ejaculates were collected from 4 different lines of boars. Samples of fresh semen were not detected with the virus and 12 sows were inseminated. Blood samples of sows and their offspring were repeatedly tested for the virus but the results were negative. We managed in this way to maintain the endangered population of this breed and obtain PRRSV-free offspring.

In our recent study we demonstrated that the holding of fresh semen in fractionated seminal plasma (SP1, >40 kDa; SP2, <40 kDa), obtained by gel filtration chromatography, significantly improved the sperm quality characteristics following cryopreservation (Wasilewska-Sakowska et al. 2019). In this study we investigated the effect of post-thaw (PT) supplementation of fractionated SP (SP1 and SP2) on the survival of spermatozoa from boars with good and poor semen freezability, GSF and PSF, respectively. Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) analysis showed distinct differences in the protein profiles of SP1 and SP2 from boars with GSF or PSF regarding the number of protein spots. Sperm motility characteristics and the motion patterns, assessed using the computer-assisted sperm analysis (CASA) system, were markedly higher in PT semen supplemented with SP1 and SP2 from boars with GSF. Post-thaw supplementation of either SP1 or SP2 from boars with GSF significantly improved mitochondrial function, plasma membrane and acrosome integrity, and viability during storage. The findings of this study have confirmed that the presence of protective protein components in varying abundance in either fractionated SP from boars with good freezability ejaculates significantly improved the sperm survival following PT storage.

In this study the quality of total RNA, isolated from fresh spermatozoa, was compared between boars with good and poor semen freezability (GSF and PSF, respectively). Semen from 3 boars with GSF exhibited significantly higher total motility, mitochondrial function, plasma membrane integrity and reduced lipid peroxidation compared with 3 boars with PSF after cryo- preservation. There were variations in the quality of RNA isolated from spermatozoa of boars with GSF and PSF. Boars with GSF exhibited mainly full-length, intact RNA, whereas substantial amounts of degraded RNA were detected in spermatozoa from boars with PSF. Further under- standing of the biological relevance of RNAs in sperm function is critical to improve the freezabil- ity of boar semen.

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 November 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.

Electrophoretic methods were used to identify protein complexes formed between ostrich egg yolk lipoprotein fractions (LPFo) with seminal plasma (SP) of fractionated ejaculates, and to investigate the effect of these complexes on boar semen quality after cryopreservation. Chromatographic SP fractions (F1, F2 and F3), with or without LPFo solution, were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Comparative electrophoretic analyses of the SP revealed marked differences in the SDS-PAGE protein profiles among boars. Electrophoretic analyses showed that the interactions of LPFo with SP resulted in the appearance of high-intensity protein bands. Spermatozoa were exposed to SP chromatographic fractions originating from F1, F2 and F3, and the whole SP (wSP) before being frozen. Spermatozoa exposed to F1 and F2 exhibited significantly higher post-thaw motility compared to those treated with either F3 or wSP. In most of the boars the proportions of membrane-intact frozen-thawed spermatozoa differed among the treatments, being significantly lower in the wSP-treated samples. The incidence of frozen-thawed spermatozoa with DNA fragmentation was less prevalent in samples exposed to F3 or the wSP. The results of this study confirmed that the interactions of LPFo with fractionated SP during the cooling period contributed to alterations in the sperm membranes, rendering them less susceptible to temperature-related injury.

Basing on Polish experience of about 5 years (since the presence of the African swine fever (ASF) in this country, starting from February 17th, 2014) and in accordance with literature the importance of the disease in wild boar is charaterised. ASF belongs to the most dangerous, very contagious diseases occurring in domestic swine and wild boar in Eurasia. In Europe, including Russia, Ukraine, Belarus, Lithuania, Latvia, Estonia, Poland, Romania, Hungary, Bulgaria, Czech Republic and Belgium ASF is existing at present and was diagnosed for short time in the frame of the Eurasian pandemy. There is a serious concern of spreading of the virus of ASF (ASFV) to other countries of Europe, not only by wild boar. However the reservoir of ASFV in this animal is playing a very important role in the maintenance of the virus and infection of pigs. Long lasting existence of ASFV in the environmnent is connected with the very high resistance to antiviral environmental factors. Following the lack of an effective immunogenic vaccine against ASF the disease can only be controlled by administrative measures. Additionally the important and recommended procedure is the significant reduction of the wild boar population. Probability of eradication of ASFV from wild boar is increased after adding quick carcass removal simultaneously by respecting biosecurity rules. If effectively implemented, fencing is more useful to delineating zones rather than adding substantially to increased efficiency of ASF control. However, segments of fencing will be particularly usefull in theses areas, where carcasses removal or intensive hunting is difficult to implement.

The present study attempted to elucidate possible routes leading to the achievement of sero- positive results, among young (aged ≤1 year) wild boar population. In the years 2017-2018, the National Reference Laboratory (NRL) for African swine fever (ASF) in Poland examined nearly 27-thousand wild boar blood samples, collected during an active surveillance of ASF risk zones, for the presence of viral DNA and anti-ASFV antibodies. Out of all the examined samples, 420 were positive. However, in more than half of them (292 samples) antibodies against African swine fever virus (ASFV) were detected, while ASFV DNA was not detected in blood. Out of all 292 seropositive/PCR-negative samples, 126 belonged to young wild boars (aged ≤1 year). For this reason, the NRL in Poland has examined 10 selected seropositive wild boar carcasses to confirm or exclude post-mortem lesions for ASF as well as to investigate the presence of viral DNA in the internal organs. Neither pathological lesions for ASF nor the presence of genetic material of ASFV were found in the examined wild boars. To elucidate this outcomes, following hypotheses about possible reasons of the obtained results were drawn: the presence of convalescent animals, infection of low-virulent ASFV isolate and the vertical transmission of antibodies through the colostrum.