The sexual function of wallowing in male wild boar (Sus scrofa)

The wild boar (Sus scrofa) is a medium-sized ungulate that produces a large variety of marks. Traditionally, wallowing is an activity that has fundamentally been related to several processes such as thermoregulation, reduction in the number of ectoparasites or disinfection of wounds in the skin of males resulting from fights to reach females. In this study, I analysed another possible function of wallowing in free-ranging wild boar populations when temperatures are low and parasitic numbers are not significant. The results indicate that during the sampling time, from October to February, the number of wild boars with a mud layer on their skin was 47, out of a total of 558 wild boar analysed. Of these 47 wild boars, 44 were males and within this group, 40 individuals were adult males. The wallowed males were bigger and older than non-wallowed males hunted at the same time. In addition, I found that males wallowed mainly during autumn (90.9% of all cases). In the total number of wild boars analysed, I did not notice individuals with wounds resulting from fights other than from the hunting day. On the other hand, the analysis of the females reproductive systems indicated that the rut period took place during the last days of October and the first days of November. From these results, the coincidence of the rut period with the maximum of wallowing in adult males could be indicative of a sexual function of this activity.     

Investigations on the radiocaesium contamination of wild boar (Sus scrofa) meat in Rhineland-Palatinate: a stomach content analysis

To substantiate the pathways of radiocaesium contamination in wild boars in parts of Rhineland-Palatinate, we analysed radiocaesium-activityconcentration of 2,433 wild boars shot in an area covering 45,400 ha in the western part of the Palatinate Forest between January 2001 and February 2003. Also, for a fraction of 689 animals shot between May 2002 and February 2003, we collected their stomachs for the examination of content and Cs-activity concentration. Wild boar meat contamination followed a seasonal curve with maximum proportions exceeding accepted levels in the summer (21–26%) and minimum levels in winter (1–9.3%) indicating a higher consumption of a contaminating source during the vegetation period. The autumn decline is obviously attributed to the extensive consumption of low-contaminated beech nuts. An exact analysis of food composition in 18 stomachs with maximum Cs-activity concentrations [345–1,749 Bq/kg (fresh matter: fm)] and 18 with low Cs-activity concentrations (20–199 Bq/kg) was carried out in the summer of 2002. Deer truffles (Elaphomyces granulatus) were found in significantly higher proportions in stomachs with maximum contamination levels than in stomachs with lowcontamination levels. This fungus was found in the Palatinate Forest, by a trained dog, in average densities of 1 truffel/20 m² primarily in spruce stands, showing an average Cs-concentration of 6,030 Bq/kg (fm). On the basis of our findings we stress the hypothesis that deer truffles function as a main Cs-source for the wild boar in Rhineland-Palatinate.     

Introduction of two chromosomal translocations of Sus scrofa nigripes and Sus scrofa scrofa into the genome of Sus scrofa domestica

Summary Hybrids between wild and domestic pigs with two types of translocations in the karyotype were studied. The translocations of type I were first detected in a population of the Middle Asian wild boars. Type II was identified in a populations of the Central European subspecies. A large number of Middle Asian and Central European hybrids and their F₁-F₃ hybrids from crosses with domestic pigs were viable. By means of differential chromosome staining, the mechanism of the formation of synthetic karyotypes, as well as some features of translocation inheritance, were established.The introduction of two translocations into a single genome and the same chromosome set of these hybrids not only modified chromosome number, but also the composition of the linkage groups. The hybrids heterozygous for two translocations and their hybrid progeny are characterized by an obligatory heterozygozity for a large number of genes, gene complexes and linked genes. It is suggested that this heterozygozity may be associated with heterotic events. The use of such hybrids in pig breeding may provide heterosis for viability and productivity.     

Grouping-patterns and inter-group relationships of Japanese wild boars (Sus scrofa leucomystax) in the Rokko mountain area

Grouping-patterns and inter-group relationships of Japanese wild boars (Sus scrofa leucomystax) were studied at a provisioning site in the Rokko mountain area, Hyogo Prefecture, Japan, from 1982 to 1983. The observations were divided into four study periods. Almost all wild boars were individually identified and their kin-relationships were followed from the beginning of the study. To examine grouping-patterns of Japanese wild boars, the degree of association between any two individuals, based on coexisting time at the provisioning site, was analyzed for each study period. Mother and her litter group (MLG), female littermate group (FLG) and solitary individual were recognized grouping-patterns. Groups did not associate with each other. Male offspring separated from their mother before 1 year of age and become solitary. Separation of female offspring occurred before the subsequent parturition of their mother. The proximate cause of separation was increased aggression by the mother. After separation, female offspring formed a FLG. However, the FLG seemed to be generally a temporary one, maintaining its stability only until parturition of it's members. Thereafter adult females had no close association with any other individuals, except for their own infants. Male offspring disappeared from their natal area, while female offspring could remain there.     

Annual and seasonal space use of different age classes of female wild boar Sus scrofa L.

In a radiotelemetric study, we analysed space use of 24 female specimens (14 family groups and 14 nonreproductive yearling females) out of 23 wild boar groups for periods between 3 and 39 months. Generally, wild boar used relatively small areas, showed high site fidelity but also a strong individual variation of home ranges, indicating a high flexibility in space use. Although age-specific differences were not statistically significant, female yearlings tended to have larger mean annual home ranges (1,185 ha MCP) than animals ranging in family groups (771 ha). Yearlings also showed a stronger shifting from spring to summer home ranges (2,345 m) and a tendency towards larger home range sizes in summer (791 ha MCP), compared to family groups (shift 1,766 m, MCP 461 ha). Yearlings displayed a dislocation of about 1 km of the annual centre in the first year after dividing from the mother. In contrast, in adults older than 2 years, the dislocation of the annual center was only 240 m.     

Investigation of wild boar (Sus scrofa) for porcine reproductive and respiratory syndrome in some territories of Russia

Samples of blood sera and internal organs were collected from 90 shot wild boars (Sus scrofa) in five regions of Russian Federation. Blood sera were tested for antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) using enzyme-linked immunosorbent assay (ELISA). In addition, samples of internal organs (lungs, lymph nodes, spleen) were tested by polymerase chain reaction (nested PCR) for PRRSV antigen. The result of our investigation showed that all samples were negative. However, PRRSV is widespread in domestic swine throughout Russia including the examined regions. Since the results show the absence of PRRSV infection in wild boars in the five examined regions of Russia, wild boars seem not to play any role in the epidemiology of PRRSV in Russia.     

Spleen size variations and reproduction in a Mediterranean population of wild boar (<Emphasis Type="Italic">Sus scrofa</Emphasis>)

We analysed spleen size variations of free-ranging wild boars from the west-central Iberian Peninsula during the hunting season (autumn and winter) in relation to the rut, the gestation effort and the attainment of sexual maturity by males and females. Females had larger spleens than males once they reached their sexual maturity. Individuals shot in winter had larger spleens than those shot in autumn, the start of the rutting period. In contrast to other reports, we found no influence of the reproductive status of adult females on their spleen sizes. Our findings may point to an influence of sex hormones, and possibly also stress hormones, and environmental factors on spleen development, mainly in adult and subadult males.     

Genetic variation in isozymes of wild boar (Sus scrofa ferus Linné)

Eleven isozyme systems were investigated in wild boar (Sus scrofa ferus L.) by means of horizontal starch gel-electrophoresis using liver and kidney extracts. Samples of 103 specimen that originated from three adjunct localities from Rhineland-Palatinate (Fed. Rep. Germany) were analysed. AAT, ACO, GDH, GPDH, LDH, ME, MPI, MR, PGDH, and PGI were invariant. Genetic polymorphism is described for PGM. The genetic polymorphism at Pgm2 is explained by a biallelic model. Observed genotypic structure did not differ significantly from Hardy-Wein-berg-proportions at this gene locus. The degree of heterozygosity is 58,3 % and Wright's Fixation Index F =–0.166 at Pgm2. The allelic structure at this gene locus differed to a great extent from that found in domestic swine, i. e. in domestic swine the faster migrating Pgm2 allozyme was only found in relative low frequencies compared to wild boar. The genetic polymorphisms were moderate in the wild boar population compared to electrophoretic data of other animal species.     

Udder preference in wild boar piglets

Competition to access the front teats in the domestic pig is strong during the first days of life, despite the fact that the number of piglets is fewer than the number of teats. Preference has been explained in terms of greater milk production (although it might also be the consequence rather than the cause), or reduced risk of crushing when the female lies down to begin a suckling session. Here, with the aim of determining whether one cause might be the body and reproductive modifications caused by artificial breeding, we analysed teat preferences of wild boar piglets in the wild. Fifty-one hunted females in lactation in the Western Iberian Peninsula were analysed. In contrast to domestic pigs, wild boar piglets showed a clear preference for rear udders. This preference was consistent for females of different ages and body characteristics, as well as for females hunted in different seasons. We suggest that the choice of rear udders in the wild boar may be related to the advantages of suckling at places offering higher protection from low temperatures and from predators, in contrast to domestic pigs, for which crushing is the main cause of mortality.     

Serosurveillance for selected infectious disease agents in wild boars (Sus scrofa) and outdoor pigs in Switzerland

The large abundance of free-ranging wild boars (Sus scrofa) and a trend towards animal friendly outdoor management of domestic pigs lead to an increasing probability of disease transmission between those animal populations. In 2001, an active monitoring was started for classical swine fever (CSF), Aujeszky’s disease (AD) and porcine brucellosis (PB) in wild boars in Switzerland. The objective of this programme was to document the serological status of wild boars regarding the selected pathogens. To continue this serosurveillance, 1,060 wild boar samples were collected during two regular hunting seasons in 2004–2005. Furthermore, in a pilot study, 61 outdoor pigs from 14 farms located in areas with high wild boar densities were sampled in 2004 and serologically tested for AD and PB. All wild boar samples were negative for CSF. Seroprevalence for AD was 2.83% (95% CI 1.91–4.02%). Seroprevalence for PB was 13.5% (95% CI 10.7–16.7%) for the Rose Bengal test and 11.05% (95% CI 8.82–13.61%) for the indirect ELISA. There was no serological evidence for AD in domestic pigs. All tested animals from 13 piggeries were seronegative for PB, but three pigs from the same farm showed doubtful results. Further investigations on the farm did not indicate the presence of PB in the herd. These findings urge the need for better diagnostic tools to obtain reliable results concerning PB prevalence. Since contact and following transmission of infectious agents between infected wild boars and outdoor pigs might occur in the future, it is advisable to include outdoor pigs in areas at risk in routine surveillance programmes.     

Tusk abnormalities in wild boar (<Emphasis Type="Italic">Sus scrofa</Emphasis> L.)

This paper describes pathological alterations in the permanent canines (tusks) of four male wild boars. The mandibular tusks of all individuals, and also some of the maxillary tusks, exhibited an extended enamel hypoplasia in their apical portion, denoting an impairment of secretory ameloblast function. Moreover, the pulp cavities of the mandibular tusks were exposed through cleft-like openings in the wear (whetting) surfaces of the teeth. Presence of a plug of reparative dentine within the pulp cavity was observed in a split mandibular tusk of one individual. In a second boar, the presence of a plug of reparative dentine within the pulp cavity of the mandibular tusks was indicated radiographically. These findings suggested a reparation process attempting to demarcate a vital, apical pulp portion from a necrotic, incisal portion. The enamel hypoplasias observed in the teeth are regarded to be sequelae of the pulp inflammation caused by bacterial invasion in the mandibular tusks. Most likely, bacterial invasion of the dental pulp occurred through the cleft-like openings in the tusks whetting surfaces, the openings resulting from insufficient formation of secondary dentine. It is, however, also conceivable that pulp inflammation and partial necrosis occurred as a consequence of bacterial invasion of patent dentinal tubules, and that the openings in the whetting surface developed secondarily as a consequence of the pulp changes. One mandibular tusk showed marked signs of resorption apically, suggesting a spread of the inflammation from the pulp into the periodontium.     

Duplication polymorphism at MHC class II DRB1 locus in the wild boar (<Emphasis Type="Italic">Sus scrofa</Emphasis>)

The origin of allelic polymorphism in genes of the major histocompatibility complex represents a central topic in evolutionary genetics as it is probably the most polymorphic region in the nuclear genome of vertebrates. Accordingly, the analyses of genetic variability at these loci provide evidence complementary to the population genetics studies based on neutral loci. In this study, four wild boar populations, two from Italy (Florence region and Castelporziano Presidential Reserve, outside Rome) and one each from Hungary and Poland, were characterized at a highly polymorphic fragment including part of intron 1 and exon 2 of swine leukocyte antigen (SLA) class II DRB1 gene by direct sequencing and by cloning. Excluding the false alleles, a total of 18 different sequences were observed in 57 individuals. The high ratio of nonsynonymous (dN) vs synonymous (dS) substitution rates in the peptide-binding region supports the hypothesis that balancing selection is operating at this locus. A duplication event at the DRB1 gene was documented only in one Italian population with both copies being putatively active. This is the first evidence of a polymorphism for the number of copies of an SLA gene.     

In-feed 0.6% ivermectin formulation for treatment of wild boar in the Moslavina hunting ground in Croatia

An in-feed 0.6% ivermectin formulation was administered for 7 days to wild boar piglets at three sites of the Moslavina hunting ground in Croatia. Examination of internal organs and skin of five piglets that died immediately before the start of administration of the ivermectin formulation revealed the presence of Metastrongylus apri and Metastrongylus pudendotectus in the lungs, and of Ascarops strongylina, Physocephalus sexalatus and Globocephalus urosubulatusin in the gastrointestinal tract. Coccidial oocysts were found in the feces of all animals. Sarcoptes scabiei var. suis was identified in the skin of four piglets. The efficacy of treatment was assessed by examining fecal samples before start of therapy (day 0) and on days 7 and 14. Before treatment strongylid-type eggs were detected in 70–100% of fecal samples (210–505 EpG) The eggs of Strongyloides ransomi, Trichuris suis, Ascaris suum, Ascarops strongylina and Physocephalus sexalatus were identified in 10–50% of fecal samples at an intensity of 5–45 EpG. On day 14 after the start of the treatment, strongylid-type eggs were detected in 10% of fecal samples from one of the three sites only. Eggs of other helminth species were not detected at any of the three sites. This confirmed the successful therapeutic efficacy of the in-feed 0,6% ivermectin formulation.     

First molecular identification of Sarcocystis miescheriana (Protozoa, Apicomplexa) from wild boar (Sus scrofa) in Iran

Sarcocystis isolate obtained from the thigh muscle of a wild boar (Sus scrofa), captured from Gilan Province, northern Iran, was subjected to molecular analysis. Genomic DNA was obtained using a DNA extraction tissue kit and Polymerase chain reaction (PCR) for amplification of the 18S ribosomal DNA region yielded an 842 bp DNA band on agarose gel. Analysis of DNA sequencing by BLAST confirmed the isolate as Sarcocystis miescheriana and the sequence was deposited in GenBank by Accession No. GU395554. This is the first molecular identification of an isolate of S. miescheriana in Iran.     

Sex differentiation in postnatal growth rate: a test in a wild boar population

Summary In wild boar individual growth rate is linear between 0.5 and 6 months after birth, based on successive body weight measurements. Contrary to expectation for a dimorphic and polygynous mammal like wild boar, no sexual dimorphism in growth rate could be detected between 0.5 and 6 months. We argue that high total maternal invesment in offspring due to large litter size and/or strong selection for early reproduction in this population with a short generation time could explain this absence of early differentiation in postnatal growth rate according to offspring sex.     

Patterns of crop damage by wild boar (Sus scrofa)in Luxembourg over a 10-year period

In many European countries, the wild boar (Sus scrofa) is often associated with crop damage. In this study, we analyse data relating to 13,276 cases of wild boar damage to agricultural crops over a 10-year period in Luxembourg (an area of 2,586 km² in Western Europe). Results show that (1) damage is more severe in this area than in others; (2) damage to permanent grassland is far more frequent and more severe than damage to annual crops; (3) trichomatous crops such as barley are avoided; (4) damage is seasonally distributed according to type of crop; (5) damage is distributed spatially in a non-uniform manner; (6) damage intensity is significantly correlated with wild boar hunting bags, both over time and space. We suggest that wild boar management strategy should always take into account the issue of damage to agricultural crops. Our results imply that measures for preventing or reducing damage should be more targeted in time and space and that adjustments to cropping patterns should contribute towards a reduction of wild boar damage.     

Influence of methylmalonyl-CoA mutase alleles on resistance to bovine tuberculosis in the European wild boar (Sus scrofa)

An association study was carried out to examine the influence of methylmalonyl-CoA mutase (MUT) polymorphisms on the susceptibility of a well-studied wild boar population from southern Spain to develop bovine tuberculosis (bTB). To this end, we examined polymorphisms at a closely linked dinucleotide microsatellite flanking exon 2 of the MUT gene in 37 wild boars with bTB and 36 non-infected individuals. The microsatellite showed low polymorphism in the studied population, with only three alleles (MUTm-A, MUTm-B and MUTm-C) found, in contrast to the 11 alleles previously reported for domestic pigs. Our case-control study showed that the MUTm-B allele was associated with disease in a dominant pattern (odds ratio = 3.36; 95% CI = 1.05-10.72; P = 0.04), while the MUTm AA genotype appeared to have a protective effect against bTB infection (odds ratio = 4.33; 95% CI = 1.20-14.96; P = 0.02). Interestingly, infected wild boars heterozygous for MUTm AB are at an advantage (11-fold) to contain the systemic spread of the disease when compared to other genotypes, implying that a balanced polymorphism may be present in the population. These results strengthen previous observations regarding the importance of the MUT gene on bTB resistance in wild boars and indicate that polymorphisms at this locus will influence the risk of acquiring and maintaining bTB in the studied population.