Craniometrical analysis of Bulgarian wild boar (Sus scrofa) populations

Skull characters of wild boars ( Sus scrofa L.) from four regions of Bulgaria were compared using stepwise discriminant, cluster of cases and principal component analyses (PCA). Classification functions were derived for discriminating individuals from different areas. Specimens from the north-eastern part of the country (Dobrudja and the Balkan Range) were found well separated from those from the south (Rila-Rhodopes & Strandja Mountains). PCA showed the differences being mostly related to the size rather than to the shape of both the cranium and the mandible. Natural migrations, intergradation areas between different subspecies, as well as restocking and hybridization with semi-domestic pigs are discussed as possible factors influencing the solution of the problem of the intraspecific systematics of the wild boar in Bulgaria.     

Daily selection of habitat in wild boar (Sus scrofa)

Spatial segregation of the sexes is observed in numerous species of ungulates, but are there other forms of segregation in species where spatial segregation is not present, such as in the wild boar? This study investigates the differences in habitat selection between two categories of individuals whose ecological requirements are supposedly divergent: subadult males, and females with dependent piglets. The proportion of the day spent in each category of habitat was used as a parameter representative of daily decisions. The overall results fit with the hypothesis that females with piglets avoid insecure habitats, and that both categories select habitats on the basis of food richness. In addition, it was found that the pattern of habitat selection depends on the total time spent moving slowly. A short duration of slow movement was observed only in males, but the time dedicated to efficient foraging (in rich habitats) was sufficient in all observations of all animals. Subadult males, therefore, do not differ from each other in foraging efficiency, but in the time spent on slow movement in secure habitats. Those spending more time active in secure habitats have the opportunity of performing more potentially beneficial activities such as social interactions and sexual contacts.     

A serological and bacteriological survey of brucellosis in wild boar (Sus scrofa) in Belgium

ABSTRACT: BACKGROUND: Brucellosis is frequently reported among wild boar populations in Europe. The aim of the study was to assess the epidemiological situation in Belgium, regarding the steady increase of wild boar populations over the last decades. Several serological tests were used and compared with culture and IS711 polymerase chain reaction (PCR), to determine the most suitable combination of diagnostic tools for conducting a successful prevalence study in wildlife. RESULTS: An indirect enzyme-linked immunosorbent assay (iELISA) was used on 1168 sera from hunter-killed wild boar sampled between 2003 and 2007 in 4 natural regions of southern Belgium. Results gave an apparent prevalence of 54.88% (95% CI 52.03-57.73). Prevalence was significantly affected by age and by the year of study, but not by sex nor by the region of sampling. The relative sensitivities of the complement fixation test (CFT), the Rose Bengal test (RBT), and the slow agglutination test (SAT) versus the iELISA differed widely between tests, reaching 62.67%, 46.68%, and 34.77%, respectively. The relative specificities of the CFT, RBT and SAT versus the iELISA were respectively 99.01%, 92.49%, and 99.1%. From seropositive animals (iELISA), 9% were positive by culture and 24% by PCR when testing spleen and/or tonsils. Sensitivity of the PCR was higher on tonsils than on spleen. All bacterial isolates were identified as Brucella suis biovar 2. CONCLUSIONS: Brucellosis is widespread among wild boar in southern Belgium, with seroprevalences having increased over ten years, and constitutes a growing risk of spillback to outdoor-farmed pig herds. The iELISA showed a better sensitivity than the CFT, RBT and SAT. Serological tests must be associated with direct diagnosis and PCR proved more sensitive than culture under wildlife sampling conditions. Spleen and tonsils are lymphoid tissues usually sampled in multi-disease monitoring programs. They remain top-grade organs for direct diagnosis of brucellosis, with a preference for tonsils.     

Genetic relationship and distribution of the Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (Sus scrofa riukiuanus) analysed by mitochondrial DNA

Mitochondrial genetic variations were used to investigate the relationships between two Japanese wild boars, Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (S.s. riukiuanus). Nucleotide sequences of the control (27 haplotypes) and cytochrome b (cyt-b) regions (19 haplotypes) were determined from 59 Japanese wild boars, 13 Ryukyu wild boars and 22 other boars and pigs. From phylogenetic analyses, the mtDNA of Ryukyu wild boar has a distinct lineage from that of Japanese wild boar, which was classified into the Asian pig lineage. This result suggests that the Ryukyu wild boar has a separate origin from the Japanese wild boar.     

Necropsy and coprology in wild boar (Sus scrofa) in Livorno Mountain Park (Tuscany, Central Italy)

The present research analyses the reliability of coprological tests, both quantitative and qualitative, as indicators of the parasite burden of hosts, using data from wild boars (Sus scrofa) living in Livorno Mountain Park (Tuscany, Central Italy). In the case of intestinal strongyles, which turned out to be the dominant helminths of wild boars, the qualitative coprological test appears as a bad predictor of the real parasite situation of the herds, due to the high number of false negative results (34 animals out of 68). On the other hand, the positive predictive value of the test is high (90%). The quantitative test is significantly correlated with the individual parasite burden of wild boars.     

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.     

Rapid establishment of teat order and allonursing in wild boar (Sus scrofa)

Transfer of milk is the fundamental common characteristic of mammalian reproduction, but species differ considerably with respect to nursing strategies. The consequences of teat orders and allonursing have been studied intensively in domestic pigs. However, whether similar nursing strategies also exist in wild boar, the ancestor of domestic pigs is so far not known. The occurrence of allonursing in wild boar is only described anecdotally, and the question whether a teat order is established has not yet been investigated. Studying suckling behaviour of 29 piglets from six primiparous wild boar females in a semi‐natural environment we found a surprisingly fast development of a rigid teat order among littermates, which established within 2.2 hr after birth. This suggests strong fitness benefits of this phenomenon that may ultimately explain the evolution and maintenance of this trait. We further found a strong synchrony of oestrus and delivery among the females of a group, as well as the occurrence of allonursing. By determining the amount of allonursing for the first time quantitatively, we demonstrate the importance of this trait and its presumably pivotal role for juvenile survival under truly natural conditions.     

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.     

Microsatellite markers for identification and parentage analysis in the European wild boar (Sus scrofa)

ABSTRACT: BACKGROUND: The wild boar (Sus scrofa) is among the most widespread mammal species throughout the old world. Presently, studies concerning microsatellites in domestic pigs and wild boars have been carried out in order to investigate domestication, social behavior and general diversity patterns among either populations or breeds. The purpose of the current study is to develop a robust set of microsatellites markers for parentage analyses and individual identification. FINDINGS: A set of 14 previously reported microsatellites markers have been optimized and tested in three populations from Hungary, Portugal and Spain, in a total of 167 samples. The results indicate high probabilities of exclusion (0.99999), low probability of identity (2.0E-13 -- 2.5E-9) and a parentage assignment of 100%. CONCLUSIONS: Our results demonstrate that this set of markers is a useful and efficient tool for the individual identification and parentage assignment in wild boars.     

黄泥河自然保护区野猪冬季栖息地利用

2009年11月-2010年1月,根据野猪的生物学特征和黄泥河自然保护区的地形、地貌特点,在研究地区布设47条样线,对保护区的野猪冬季栖息地利用进行了研究,测定了野猪对海拔、坡位、坡向、坡度、植被类型、郁闭度、树高度、树胸径、食物丰富度、隐蔽度、离水源距离和离人为干扰距离等12种生态因子的选择利用情况.结果表明:黄泥河自然保护区野猪冬季多活动在海拔≤1000 m,坡下位的阳坡平坦地带,食物丰富度高,隐蔽度强,郁闭度中等,且离水源≤500 m,离人为干扰>2000 m的阔叶林和针阔混交林内;主成分分析表明,栖息地变量前4个特征值的累积贡献率达到77.5%,较好地反应了野猪的栖息地特征;影响野猪栖息地选择的关键因子是海拔、坡度、离人为干扰距离,次要因子是离水源距离、隐蔽度、树胸径.     

Epidemiological study of the intestinal helminths of wild boar (Sus scrofa) and mouflon (Ovis gmelini musimon) in central Italy

Since 1995 the population of wild ungulates increased significantly in the "Parco provinciale dei Monti Livornesi" (Livorno, Tuscany, Central Italy). We studied the intestinal macroparasites of two hosts, the wild boar (Sus scrofa) and the mouflon (Ovis gmelini musimon). In the case of wild boars we found a dominant parasite species, Globocephalus urosubulatus. For this parasite the frequency distribution of the number of parasites per host agrees with a negative binomial distribution. There is not a significant correlation between the age of the animals and the parasitosis. Furthermore the mean parasite burden of male and female wild boars does not differ significantly. In the case of mouflons we found a dominant parasite species Nematodirus filicollis with Trichuris ovis as codominant species.     

Antibodies to selected pathogens in wild boar (Sus scrofa) from Catalonia (NE Spain)

From 2004 to 2007, blood samples from 273 healthy wild boars (Sus scrofa), culled during the hunting season, were obtained in three areas of Catalonia (NE Spain): Pyrenees, Sant Llorenç del Munt i l’Obac Natural Park (SLM), and Ports de Tortosa i Beseit National Hunting Reserve (PTB). We investigated the presence of antibodies against classical swine fever virus (CSFV), African swine fever virus (ASFV), porcine vesicular disease virus (PVDV), porcine respiratory and reproductive syndrome virus (PRRSV), Aujeszky’s disease virus (ADV), porcine influenza A virus (PIV), porcine circovirus type 2 (PCV2), porcine parvovirus (PPV), Mycoplasma hyopneumoniae, Erysipelothrix rhusiopathiae, Salmonella spp., and Toxoplasma gondii. Four wild boars were suspicious for CSFV, but the infection was discarded with a virus neutralization test, and infection with a border disease virus was confirmed. Negative results were obtained against ASFV and PVDV. Antibodies were detected against PRRSV (3%), ADV (0.8%), PIV (6.4%), PCV2 (64.6%), PPV (54.7%), M. hyopneumoniae (26.6%), E. rhusiopathiae (5.3%), Salmonella spp. (11.3%), and T. gondii (43.5%). In SLM, we detected a higher seroprevalence for PIV and M. hyopneumoniae and a lower seroprevalence for E. rhusiopathiae than in the other two areas. In PTB, seroprevalence was higher for PPV, Salmonella spp., and PCV2. Adult wild boar displayed higher seroprevalence for PPV, PIV, and M. hyopneumoniae, whereas presence of antibodies for Salmonella spp. was higher in juveniles compared with adults and piglets.

     

On the evolutionary consequences of increasing litter size with multiple paternity in wild boar (Sus scrofa scrofa)

Understanding how some species may be able to evolve quickly enough to deal with anthropogenic pressure is of prime interest in evolutionary biology, conservation, and management. Wild boar (Sus scrofa scrofa) populations keep growing all over Europe despite increasing hunting pressure. In wild boar populations subject to male‐selective harvesting, the initially described polygynous mating system may switch to a promiscuous/polyandrous one. Such a change in the mating system, where potentially more males sire a litter at one reproductive event, may be associated with the retention of high genetic diversity and an increase of litter size. We tested these hypotheses by estimating the number of sires per litter based on a six‐year long monitoring of a wild boar population subject to particularly high harvesting pressure. Our results show a high and stable genetic diversity and high rates of multiple paternity compared to other populations, thus depicting a promiscuous/polyandrous mating system in this population. We also show that litter size is positively linked to the number of sires, suggesting that multiple paternity increases fecundity. We finally discuss that multiple paternity may be one of the factors allowing rapid evolution of this population by maintaining both genetic and phenotypic diversity.     

Testis morphometry, duration of spermatogenesis, and spermatogenic efficiency in the wild boar (Sus scrofa scrofa)

The wild boar is a natural inhabitant of Europe, Asia, and North Africa and is phylogenetically the ancestor of the domestic pig. Because of its phylogenetic and economic importance, this species is an interesting model for studying testis function in boars. Therefore, the present study was performed to investigate the testis structure, spermatogenic cycle length, and Sertoli cell (SC) and spermatogenic efficiencies in eight adult wild boars. Each spermatogenic cycle lasted 9.05 days, and the total duration of spermatogenesis was estimated as lasting approximately 41 days. The percentages of testis volume occupied by seminiferous tubules and by Leydig cells were 87% and 6%, respectively. The mean number of SCs per gram of testis was 42 million. The SC (round spermatids per SC) and spermatogenic (daily sperm production per gram of testis) efficiencies were 6.6 cells and 28.6 million, respectively. In general, the testis structure, overall germ cell associations at the different stages of the seminiferous epithelium cycle, and duration of spermatogenesis in the wild boar were similar to those in domestic pigs. Probably because of the small size of Leydig cells (400 microm3), their number per gram of testis (157 million) was the highest among investigated mammalian species. Although the SC efficiency in wild boars was low, their spermatogenic efficiency was comparable to that observed in domestic pigs, mainly because of the higher number of SCs per gram of testis in wild boars. These data suggest that SCs became more efficient during evolution, genetic selection, and domestication in pigs.     

Presence of antibodies against Aujeszky's disease virus in wild boar (Sus scrofa) in Slovenia

Serum samples from 427 hunter-killed wild boar (Sus scrofa) from Slovenia were tested for antibodies to Aujeszky's disease virus (ADV). Samples were collected throughout Slovenia and corresponded to 6.2% of the total harvest. Antibodies against ADV were detected in 111 sera (26%) using a commercial enzyme-linked immunosorbent assay (ELISA). Antibody prevalence increased significantly with age. This report describes the first evidence of ADV infection in wild boar populations in Slovenia.