Hair diameter distribution in sheep interspecies hybrids

Hair diameter distribution was studied in wild sheep species (argali—Ovis ammon, mouflon—O. Musimon; domestic sheep—O. aries) and their hybrids. In wild species and their hybrids, rather distinctly separated subpopulations of thin (underwool) hairs (10–22 μm diameter) and thick (kemp) hairs (85–302 μm) were detected, and intermediate diameters were rare. In domestic sheep, the kemp subpopulation was very poor, not distinctly separated from the underwool, while maximal hair diameter was <150 μm. In wild × domestic crosses, the kemp subpopulation was clearly expressed, shifted to lower diameter range, and maximal diameters was <200 μm. The same restriction was found in two-month-old wild species lambs compared with adults.     

Detection of hybrids between wild boars (Sus scrofa scrofa) and domestic pigs (Sus scrofa f. domestica) in Greece,using the PCR-RFLP method on melanocortin-1 receptor (MC1R) mutations

The melanocortin-1 receptor (MC1R) regulates melanogenesis in mammals within the mammalian melanocyte and the hair follicle. Common variations (polymorphisms) in the MC1R gene are associated with normal differences in skin and hair colour. So far, a unique MC1R allele (E+) has been identified in European wild boar (Sus scrofa scrofa), associated with the wild-type coat colour (variable shades of brown) that is not found in any of the domestic breeds. In addition, a series of alleles found in pigs, some of which observed only in particular breeds, have been proposed as markers in breed traceability systems. The current study is an attempt to detect possible hybrids between wild boars and domestic pig breeds as well as to identify races of pig that are not purebred. For this purpose, wild boars were analysed against Large White pigs, applying the PCR-restriction fragment length polymorphism (RFLP) method. A high percentage (16.7%) of hybrids was detected within a breeding station compared with the percentage of hybrids within the populations of free-ranging wild boar (5.0%). These results should be taken into consideration for future restocking operations to avoid the chance of outbreeding depression, which is more intense when local populations are introgressed by gene pools from domesticated, usually inbred, animals.     

Porcine reproductive and respiratory syndrome (PRRS) virus in wild boar and Iberian pigs in south-central Spain

Porcine reproductive and respiratory syndrome (PRRS) is a swine infectious disease causing major economic problems on the intensive pig industry. This virus has been reported worldwide in domestic pigs and there is evidence of PRRS virus (PRRSV) infection in wild boar (Sus scrofa). Nonetheless, the epidemiological role of wild boar and extensively kept domestic pigs remains unclear. The aim of this study was to determine the occurrence of PRRS in wild boar and Iberian pigs in the dehesa ecosystem of the Castile-La Mancha region of Spain, which boasts one of the most important free-roaming porcine livestock and hunting industries in the country. Using geo-spatial analysis of literature data, we first explored the relationship between domestic pig density and PRRS occurrence in wild boar in Europe. Results revealed that PRRS occurrence in wild boar may be influenced, albeit not significantly, by domestic pig density. Next, we analyzed sera from 294 wild boar and 80 Iberian pigs by indirect enzyme-linked immunosorbent assay for PRRSV antibodies. The sera and 27 wild boar tissue samples were analyzed by two real-time RT-PCR assays, targeting the most conserved genes of the PRRSV genome, ORF1 and ORF7. Seven wild boar (2.4 %) and one Iberian pig (1.3 %) were seropositive, while none of the animals tested positive for PRRSV by RT-PCR. Our results confirm the limited spread of PRRSV in free-roaming Iberian pigs and wild boar living in mutual contact. Further studies would be necessary to address whether this low seroprevalence found in these animals reflects transmission from intensively kept pigs or the independent circulation of specific strains in free-roaming pigs.     

Are wild boars roaming Ireland once more?

Wild boars (Sus scrofa) have been increasingly sighted in the wild in Ireland during the last few years, likely due to illegal releases and/or escapees. The species has since been designated an invasive species in Ireland, which is seen as controversial by some because of uncertainties about the historic status of the species in Ireland. However, just as pertinent to the argument is the genetic purity of these individuals currently found in Ireland: are these pure wild boars? We carried out a genetic assessment of 15 wild boars shot in Ireland between 2009 and 2012 using 14 microsatellites and mitochondrial DNA (mtDNA). These were compared to European wild boar, domestic pig breeds and a hybrid population of ‘wild boar’ from England. Microsatellite analysis revealed that almost all the Irish individuals belonged to the ‘domestic pig’ genetic cluster, with only three individuals being classified as hybrids. All but two individuals carried Asian mtDNA haplotypes, indicating a domestic pig origin. It is clear from this study that the individuals currently found in Ireland are not pure wild boars and this result has to be factored into any management/eradication plans.     

Genetic diversity in the European wild boar Sus scrofa: phylogeography,population structure and wild x domestic hybridization

• 1 Despite the vast literature on genetic variation in the domestic pig Sus scrofa, little is known about genetic differentiation in wild boar populations.
• 2 Here we present an up‐to‐date review of published data on the past and recent history of the European wild boar, its genetic diversity and the spatial distribution of genetic variation throughout the continent.
• 3 The phylogeography of the species seems to be shaped mostly by past large‐scale events (like postglacial recolonization) rather than by more recent human manipulation. Genetic differentiation is observed both on a continental and a regional scale, and non‐intuitive barriers to gene flow occur.
• 4 From an indirect estimate, hybridization between wild boar and domestic pigs is seemingly a minor source of genetic variation for wild boar populations, yet risks are still linked to the release of captive hybrids in some areas.
• 5 Finally, we present future perspectives concerning the development of powerful molecular tools and their possible application to the study and management of this species.

     

Epidemiological risk factors of Aujeszky’s disease in wild boars (<Emphasis Type="Italic">Sus scrofa</Emphasis>) and domestic pigs in Spain

An Aujeszky’s disease (AD) control and eradication campaign started in Spain in 1995, and as a result, AD virus (ADV) seroprevalences have notably diminished in Spanish domestic pig herds, but eradication has not yet been achieved. Since the presence of ADV in Spanish wild boar populations can impede schemes to eradicate ADV in domestic pig, we conducted analyses of risk factors and investigated associations between the patterns of ADV seroprevalence at the municipal level in the wild boar and the domestic pig, respectively, in south-central Spain. There was a clear influence of individual factors on the risk of wild boar to test positive to ADV. Concerning the domestic pig, higher ADV seroprevalences were observed with increasing numbers of pigs per farm. Indoor pig farms showed higher seroprevalences than open-air farms. Our results show that, at least at the study scale, the level of ADV seroprevalence in domestic pig farms is not influenced by the level of ADV seroprevalence in the coexisting wild boar populations. Also, there was no influence of domestic pigs ADV seroprevalence on the risk of wild boars to test seropositive. Finally, there was no evidence for a statistical association between ADV seroprevalence levels in wild boar and domestic pig at the municipal level in the study region. These findings are of interest for both veterinary and public health authorities. Nevertheless, more effort is needed in order to elucidate the nature of particular ADV outbreaks in domestic pigs in the study region due to possible contacts with wild boars, which will probably require a molecular approach.     

Histological characteristics of longissimus dorsi muscle and their correlation with restriction fragment polymorphisms of calpastatin gene in F2 Jinghua × Piétrain crossbred pigs

In order to evaluate the genotype of the calpastatin (CAST) gene and its relationship to muscle histology and other post mortem traits in the Jinhua × Piétrain F2 pig family, 158 barrows and gilts were electrically stunned and exsanguinated. Both blood and muscle samples were collected, and both post mortem traits and meat qualities were recorded. Restriction fragment length polymorphism (RFLP) analysis, the periodic acid Schiff reaction (PAS) and myosin heavy-chain immunohistochemistry were employed to explore the relationship between genotype and muscle histology. Based on PAS reactivity, muscle fibres can be classified into three types: PAS (-), PAS (+) and PAS (++). Myosin heavy-chain immunohistochemistry can differentiate muscle fibres into either slow or fast fibres; the proportion of slow and fast fibres were 6% and 94%, respectively. When the amplification products of the CAST gene were digested with MspI, HinfI and RsaI, two different cleavage patterns could be discriminated from the endonuclease map detected using each enzyme. The results showed that the polymorphisms detected using these three endonucleases are identical. Only three genotypes (AA/CC/EE, AB/CD/EF and BB/DD/FF) were distinguished. Their frequencies were 0.1835, 0.5823 and 0.2342, respectively. Different genotypes had significant association with area and pH45m value of loin muscle, while showing no significant association with the water-holding capacity and conductivity of loin muscle. The results also revealed that the genotypes had a significant correlation with diameter, area, circularity and the aspect ratio of muscle fibres. It was also presented that the genotypes significantly correlated with the percentage of intramuscular connective tissue.     

The origin of the domestic pig: independent domestication and subsequent introgression

The domestic pig originates from the Eurasian wild boar (Sus scrofa). We have sequenced mitochondrial DNA and nuclear genes from wild and domestic pigs from Asia and Europe. Clear evidence was obtained for domestication to have occurred independently from wild boar subspecies in Europe and Asia. The time since divergence of the ancestral forms was estimated at approximately 500,000 years, well before domestication approximately 9,000 years ago. Historical records indicate that Asian pigs were introduced into Europe during the 18th and early 19th centuries. We found molecular evidence for this introgression and the data indicated a hybrid origin of some major "European" pig breeds. The study is an advance in pig genetics and has important implications for the maintenance and utilization of genetic diversity in this livestock species.     

High domestic pig contribution to the local gene pool of free-living European wild boar: a case study in Poland

Rates of hybridization between wild and domesticated animals appear to be increasing worldwide. Recent results suggest that genetic introgression from domestic swine into European wild boar is much more common in local populations than expected, based on pan-European studies. Thus, we screened the genetic purity of 265 free-living wild boars from two hunting areas in Poland by genotyping the melanocortin receptor 1 gene (MC1R) for polymorphism. Unexpectedly, high numbers of individuals with domestic genes (24%) were identified. This suggests that mixed ancestry may be common in Polish wild boar. Among admixed individuals, backcrosses with domestic pig and/or introgressed wild boars were detected (2%). Multiple commercial domestic pig breeds are possibly involved in the introgression observed in the study populations. In addition, the absence of significant differences in the frequency of wild-type allele among two hunting areas suggests high dispersal of individuals and gene flow among populations. We conclude that further study is needed to better understand the mechanisms and sources of introgression in wild boars in Poland.     

Phenotype and animal domestication: A study of dental variation between domestic,wild, captive,hybrid and insular Sus scrofa

Background

Identifying the phenotypic responses to domestication remains a long-standing and important question for researchers studying its early history. The great diversity in domestic animals and plants that exists today bears testament to the profound changes that domestication has induced in their ancestral wild forms over the last millennia. Domestication is a complex evolutionary process in which wild organisms are moved to new anthropogenic environments. Although modern genetics are significantly improving our understanding of domestication and breed formation, little is still known about the associated morphological changes linked to the process itself. In order to explore phenotypic variation induced by different levels of human control, we analysed the diversity of dental size, shape and allometry in modern free-living and captive wild, wild x domestic hybrid, domestic and insular Sus scrofa populations.

Results

We show that domestication has created completely new dental phenotypes not found in wild boar (although the amount of variation amongst domestic pigs does not exceed that found in the wild). Wild boar tooth shape also appears to be biogeographically structured, likely the result of post-glacial recolonisation history. Furthermore, distinct dental phenotypes were also observed among domestic breeds, probably the result of differing types and intensity of past and present husbandry practices. Captivity also appears to impact tooth shape. Wild x domestic hybrids possess second molars that are strictly intermediate in shape between wild boar and domestic pigs (third molars, however, showing greater shape similarity with wild boar) while their size is more similar to domestic pigs. The dental phenotypes of insular Sus scrofa populations found on Corsica and Sardinia today (originally introduced by Neolithic settlers to the islands) can be explained either by feralization of the original introduced domestic swine or that the founding population maintained a wild boar phenotype through time.

Conclusions

Domestication has driven significant phenotypic diversification in Sus scrofa. Captivity (environmental control), hybridization (genome admixture), and introduction to islands all correspond to differing levels of human control and may be considered different stages of the domestication process. The relatively well-known genetic evolutionary history of pigs shows a similar complexity at the phenotypic level.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-014-0269-x) contains supplementary material, which is available to authorized users.     

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.     

Investigating the Role of Free-Ranging Wild Boar (Sus scrofa) in the Re-Emergence of Enzootic Pneumonia in Domestic Pig Herds: A Pathological,Prevalence and Risk-Factor Study

Enzootic pneumonia (EP) caused by Mycoplasma hyopneumoniae has a significant economic impact on domestic pig production. A control program carried out from 1999 to 2003 successfully reduced disease occurrence in domestic pigs in Switzerland, but recurrent outbreaks suggested a potential role of free-ranging wild boar (Sus scrofa) as a source of re-infection. Since little is known on the epidemiology of EP in wild boar populations, our aims were: (1) to estimate the prevalence of M. hyopneumoniae infections in wild boar in Switzerland; (2) to identify risk factors for infection in wild boar; and (3) to assess whether infection in wild boar is associated with the same gross and microscopic lesions typical of EP in domestic pigs. Nasal swabs, bronchial swabs and lung samples were collected from 978 wild boar from five study areas in Switzerland between October 2011 and May 2013. Swabs were analyzed by qualitative real time PCR and a histopathological study was conducted on lung tissues. Risk factor analysis was performed using multivariable logistic regression modeling. Overall prevalence in nasal swabs was 26.2% (95% CI 23.3–29.3%) but significant geographical differences were observed. Wild boar density, occurrence of EP outbreaks in domestic pigs and young age were identified as risk factors for infection. There was a significant association between infection and lesions consistent with EP in domestic pigs. We have concluded that M. hyopneumoniae is widespread in the Swiss wild boar population, that the same risk factors for infection of domestic pigs also act as risk factors for infection of wild boar, and that infected wild boar develop lesions similar to those found in domestic pigs. However, based on our data and the outbreak pattern in domestic pigs, we propose that spillover from domestic pigs to wild boar is more likely than transmission from wild boar to pigs.     

Prevalence and spatiotemporal distribution of African swine fever in Lithuania, 2014–2017

Background

The emergence in 2014 and persistence of African Swine Fever (ASF) in Lithuania has been linked to infected wild boar movement and close contact with the carcasses of other infected wild boars. Over time the number of reported cases of ASF in wild boars gradually increased, but no detailed epidemiological data has been available. Therefore, the objective of the present study was to determine ASF virus prevalence in wild boars and domestic pigs during the 2014–2017 period and further explore the current geographical distribution of the virus.

Results

Our study results show that ASF virus prevalence in hunted wild boars using PCR analysis increased from 0.83% (95% CI 0.69–0.98) to 2.27% (95% CI 2.05–2.48) from 2014 to 2016 respectively. However, there was a dramatic jump in the number of ASF positive wild boars cases in 2017 resulting in prevalence of 12.39% (95% CI 11.91–12.86) (p <?0.05).The average prevalence of ASF-specific antibodies in wild boar population during years 2014–2017 was 0.45% (95% CI 0.39–0.51) based on ELISA test results.Prevalence of ASF virus in domestic pigs ranged from 0.24% (95% CI 0.17% - 0.32) in 2015 to 2.74% (95% CI 2.33% - 3.15) in 2017. The average seasonal prevalence of ASF virus in pigs was statistically significant (p?<?0.05) and ranged from 0% in spring to 3.68% (95% CI 3.32–4.05) in summer. Correlation between the pig density and number of recorded pig ASF cases in affected regions was only found in 2017 (R =?0.78, p?<?0.05). No correlation was detected between the wild boar density and number of recorded pig or wild boar ASF - positive cases.

Conclusions

This study provides the first results of ASF virus prevalence changes in Lithuania during the 2014–2017. The overall results confirm the relatively high prevalence of ASF virus in wild boar that was gradually increasing from 2014 to 2017. In the last year of study, the number of ASF positive cases in both domestic pigs and wild boars had unexpectedly increased several times. A better understanding of current status of the disease will enable better control and prevent further spread of ASF virus in Western Europe.

     

6个中国猪地方品种和3个瑞典猪DNA分子系统发育相关关系

线粒体DNA遗传多样性用于评价6个中国地方猪种和3个瑞典家猪系统发育关系。采用PCR和序列分析方法得到了来自9个品种140头猪的线粒体中控制区440bp和细胞色素b基因798bp核苷酸序列。系统发育分析结果表明：6个中国地方猪种起源于亚洲野猪。中国地方猪种和欧洲野猪的线粒体DNA核苷酸序列变异发生在413000－875000年以前,而亚洲紧猪的变异仅发生在7000－156000上以前,由于2000年以前或18世纪初中国猪种导入欧洲家猪,因此瑞典家猪既属于欧洲类也属于亚洲类。     

The origin and genetic differentiation of native breeds of pigs in southwest China: An approach from mitochondrial DNA polymorphism

Mitochondrial DNA (mtDNA) of six breeds of native domestic pigs from Yunnan province, southwest China, and two wild boars obtained from Sichuan, China, and Vietnam was analyzed using 20 restriction endonucleases that recognize six nucleotides. Restriction maps were made by double-digestion methods and polymorphic sites were located on the map. According to their mtDNA restriction types, all the breeds were classified into six groups. Genetic distances among groups were calculated to define their phylogenetic relationships. The relationship between the Sichuan wild boar and domestic pigs is close, while the Vietnamese wild boar is relatively far from them, so the domestic pigs in southwest China are likely to have originated from a wild pig which distributed in west China. We compare our results with previous reports in literature and discuss the relationship among Chinese pigs, Japanese pigs, and European pigs. The mtDNA cleavage pattern of the Mingguang pig digested byEcoRV was identical to that of Duroc; mutations at theEcoRI site, detected in the mtDNA of two Dahe pigs, are the same as in the Vietnamese wild boar, suggesting that mutational hot spots exist in the mtDNA of pigs.     

野猪及其与家猪杂种猪Myostatin基因3'编码区的克隆和序列分析

Myostatin, which is a highly conservative gene among breeds, is a negative regulator of muscle. The 3' coding region of wild boar and crossbred pig myostatin was cloned by RT - PCR and sequenced. Compared with that of GenBank, the homology of the nucleotide sequence between wild bear and crossbred pig is identical in this region indicating that domestic pigs were evolved from wild boar and there was not changed in this region during the evolution processes.     

Sexual differences in the increase of white muscle fibres in Argentine hake, Merluccius hubbsi, from the San Matias Gulf (Argentina)

Growth dynamics of white fibres from axial muscle has been investigated in Argentine hake, Merluccius hubbsi , discriminating between sexes for the first time. The frequency distributions of fibre diameters are remarkably different in both sexes at sizes between 42 and 63·9 cm total length (T.l.). Males have a much lower proportion of newly recruited fibres (0–10 μm) than females; at 52–53·9 cm T.l., females have 4% of fibres in that category and males 0·5%. It appears that, from this size interval onwards, the increase in muscle mass is due only to the increase in diameter of individual fibres, which may exceed 300 μm. The lower recruitment rate of new fibres in males, and its relationship to lower growth rates and smaller final sizes, are discussed, and possible effects of reproductive activity are considered.     

In vitro penetration assay of boar sperm fertility: effect of various factors on the penetrability of immature pig oocytes

The present study was designed 1) to examine the influence of cumulus cells, ovary storage time and oocyte size on the penetrability of immature pig oocytes, and 2) to investigate the effect of 2 methods of treating the semen from different boars on the inter-assay variability of homologous in vitro penetration tests of boar sperm fertility. In Experiment 1, cumulus oocyte complexes, oocytes with spontaneous loss of the cumulus cells during collection, and oocytes mechanically stripped of cumulus cells were used. No differences were observed in oocyte penetrability among the 3 types of oocyte, although mechanical removal of the cumulus caused an increase (P < 0.005) in the degeneration rate compared with the other oocyte types. In Experiment 2, the oocytes were recovered from ovaries kept in PBS (30 degrees C) for 2, 4 or 6 h after slaughter of prepuberal gilts. Ovary storage did not modify the penetrability of oocytes but increased (P < 0.02) their degeneration rates. In Experiment 3, the diameters of fresh oocytes were determined after co-incubation with spermatozoa. They were classified into 4 groups according to diameter: A) < 105 microm, B) 105-115 microm, C) 116-120 microm and D) > 120 microm. Oocytes from Groups C and D exhibited higher (P < 0.05) penetrability than oocytes from the other groups. In Experiment 4, stored, diluted spermatozoa from 4 boars were pretreated by centrifugation at 50 x g for 3 min and subsequent concentration of the supernatants at 1,200 x g for 3 min. The pellets were treated (washed twice and preincubated for 40 minutes) before co-incubation with immature oocytes or used directly as untreated samples (unwashed and non-preincubated). A boar effect (P < 0.001) was evident for the parameters of in vitro penetration, independently of sperm treatment. When the oocytes were inseminated with untreated spermatozoa, the effects of the replicate and the boar-by-replicate interaction on the variability in oocyte penetrability were not significant. The results of this study indicate that the use of standardized immature pig oocytes and stored untreated, diluted spermatozoa can provide a useful method for optimizing the homologous in vitro penetration (hIVP) assay of boar fertility.     

The phylogeny of Chinese indigenous pig breeds inferred from microsatellite markers

A genetic study of 32 local Chinese, three foreign pig breeds [Duroc (DU), Landrace and Yorkshire], and two types of wild boar (Hainan and Dongbei wild boar) based on 34 microsatellite loci was carried out to clarify the phylogeny of Chinese indigenous pig breeds. The allele frequencies, effective numbers of alleles, and the average heterozygosity within populations were calculated. The results showed that the genetic variability of the Lingao pig was the largest, while the Jiaxing pig was the lowest. The greatest distance between domestic pigs was found between Shanggao and DU pig and the shortest was found between Wuzhishan and Lingao pig, respectively. A neighbour-joining tree constructed from Modified Cavalli-Sforza genetic distances divided Chinese pigs into two clusters; four subclusters were also identified. Our results only partly agree with the traditional types of classification and also provide a new relationship among Chinese local pig breeds. Our data also confirmed that Chinese pig breeds have a different origin from European/American breeds and can be utilized in programmes that aim to maintain Chinese indigenous pig breeds.     

The effects of two oestrus detection procedures and intense boar stimulation near the time of oestrus on mating efficiency of the female pig

In the first experiment, a higher oestrus detection rate (percentage of cycling gilts that were detected in oestrus) and a higher mating rate (percentage of cycling gilts that were mated) were achieved when cycling gilts were checked for oestrus in the corridor adjacent to the boar pens than when they were checked in their own pens, which were separated from the boar pens by a 1.0 m-wide corridor (90 v. 52% and 87 v. 52%, respectively). In the second experiment, several housing treatments were imposed over a 21-day period. A lower proportion of gilts were detected in the I stage of oestrus (positive response to the back-pressure test both in the presence and absence of a boar) and a lower mating rate was achieved when cycling gilts were separated from the boar by a wire-mesh pen division than when separated by a 1.0 m corridor (48 v. 81% and 47 v. 81%, respectively). It was concluded that cycling females should be housed near, but not adjacent to, boars and that at the time of oestrus detection using the back-pressure test, females should be very close to boars.