BACTERIAL FLORA OF SEMEN OF WILD BOAR AND THEIR HYBRIDS WITH DOMESTIC PIG

Roland Kozdrowski¹, Zdzisław Staroniewicz², Andrzej Dubiel^3
1 Department and Clinic of Obstetrics, Ruminant Diseases and Animal Health Care, Wrocław University of Environmental and Life Sciences, Poland
² Department of Pathology, Physiopathology, Microbiology and Forensic Veterinary Medicine, Agricultural University of Wrocław, Poland
³ Department and Clinic of Reproduction, Ruminants Diseases and Animal Health Protection, Agricultural University of Wrocław, Poland

ABSTRACT

The objective of the study was a bacteriological examination of semen of wild boar and wild boar-domestic pig hybrid. Besides saprophytic bacterial flora, the following bacteria were detected: Escherichia coli, Pseudomonas aeruginosa, Enterobacter spp. The results suggest that the bacterial flora of the examined males is close to that of domestic boar semen.

Key words: wild boar, semen, bacterial flora.

INTRODUCTION

Interest in farm keeping of wild boar and their hybrids with domestic pig has been growing recently in Poland and other European countries [1, 2, 3]. The increased interest in keeping wild animals results from the development of agrotourist farms and ecological agriculture. Introducing wild animals in such farms brings about the risk of transmission of many infectious diseases. For this reason examination of animals which are to be introduced towards possible transmission of infectious diseases is advisable. Catching wild boars which are then used to mate with domestic sows in order to obtain hybrids is a common practice. Meat of the hybrids is of a higher quality with respect to its appearance, taste and durability compared to pork, which justifies attempts at producing hybrids. It should be borne in mind that the semen of wild boar, like that of domestic boars, may be a source of an array of pathogenic factors, including pathogenic bacteria such as e.g. Brucella suis, contributing to spread of sexually-transmitted infectious diseases. In the literature there are no data on the bacterial flora of wild boar semen, and thus the aim of the study was a bacteriological examination of wild boar and hybrid semen.

MATERIALS AND METHODS

Three wild boars aged 3-4 years and 4 hybrids aged 12 months were examined. All the animals were clinically healthy, and the semen obtained from them was used to inseminate domestic sows. Properties of the semen did not depart from the standards adopted for the domestic boar semen. The semen was sampled "by hand" using a sow or a phantom as a stimulant (Fig. 1 and Fig. 2). Immediately after sampling the semen was filtered trough gauze in order to separate the liquid and gelatinous fractions. A total of 167 ejaculates were obtained from wild boars and 257 from hybrids during the 14 months. During this period 17 ejaculates from wild boars and 48 ejaculates from hybrids were selected at random and just after filtration the semen was subject to standard bacteriological examination.

Fig. 1. Semen collection from wild boar

Fig. 2. Semen collection from hybrid

RESULTS

Data on bacteriological contamination of the wild boar and hybrid semen are presented in tab. 1. The bacteriological examination of the semen of wild boars and hybrids showed a similar degree of bacteriological contamination. In wild boars, 1 ml fresh semen contained on an average 2177.06 bacteria, in hybrids 2584.21. The ejaculates differed considerably in the number of bacteria, as indicated by high standard deviation, of 2793.39 and 5061.37 for wild boars and hybrids, respectively.

Table 1. Bacterial flora of semen of wild boar and wild boar/domestic pig hybrid

Boars	Number of examined ejaculates	Number of bacteria per 1 ml semen (mean ± standard deviation)	Percentage of ejaculates contaminated with Escherichia coli	Percentage of ejaculates contaminated with Pseudomonas aeruginosa	Percentage of ejaculates contaminated with Enterobacter spp.
Wild boars	17	2177.06 ± 2793.39	52.90	29.41	5.88
Hybrids	48	2584.21 ± 5061.37	45.80	6.25	10.42

Besides the saprophytic bacterial flora, there were also conditionally pathogenic and pathogenic bacteria. Escherichia coli was isolated from 45.8% hybrid ejaculates and 52.9% hybrid ejaculates. Pseudomonas aeruginosa was found in 6.25% hybrid (3 ejaculates from the same male) and 29.41% wild boar ejaculates. Bacteria of the genus Enterobacter were isolated from 10.42% hybrid and 5.88% wild boar ejaculates.

DISCUSSION

The mean number of bacteria per 1 ml semen, of 2177.06 and 2584.21 in wild boars and hybrids, respectively, indicates a low degree of bacteriological contamination. It is assumed that domestic boar semen containing below 50 x 10³ bacteria in 1 ml shows a low degree of bacteriological contamination [4]. The analysed ejaculates showed a wide variation in the number of bacteria per unit volume which is in agreement with literature data on bacteriological contamination of domestic boar semen [5, 6]. The number of bacteria in domestic boar ejaculates is affected by the method of sampling, degree of contamination of diverticulum preputiale and, mainly, the hygienic conditions of sampling [6]. Because of the low bacteriological contamination of the studied semen, the effect of bacteria on its quality can be excluded. Qualitative analysis of the ejaculates showed that the dominant bacterium was Escherichia coli (in wild boars 52.9%, in hybrids 45.8%). Also Dubiel et al. [6] found that in domestic boar semen Escherichia coli was the most frequent bacterium (70%). Domestic boar semen may also contain, among others: Brucella suis, Leptospira spp., Mycoplasma spp., Ureoplasma spp. and an array of pathogenic viruses [7]. Our studies did not include virological examination of the semen, and we did not find the above-mentioned bacterial pathogenic factors which, however, does not exclude their transmission through wild boars. Considering the fact that wild boars may constitute an epizootic threat for pig farming, introducing wild boars into farms should always be preceded by serological examination which will save the breeder unpleasant consequences. Also regular bacteriological examination of semen will allow monitoring of health condition of the reproductive system of the wild boars destined for breeding which should decrease the probability of spread of sexually-transmitted infectious diseases of wild boars and domestic pigs.

REFERENCES

1. Głowacka B., Gruszka H.: Zalety i wady hodowli zagrodowej dzika (Sus scrofa). [Pros and Conos of Fenced Wild Boar (Sus scrofa) Breeding]. Sylwan 1996, 140, 69 - 76. [in Polish].

2. Kyle R.: Wild boar in Britan: a new farming enterprise. St. Vet. J. 1995, 5, 10 -12. (Abstr.).

3. Walkiewicz A.: Dziki, świdziki, dzikoświnie - czy taki agrobiznes w Polsce się rozwinie. [Wild boars, hybrids - is there possibility to develop that kind of agrobusiness in Poland]. Trzoda chlewna 1996, 8, 94 - 96. [in Polish].

4. Bronicka A., Dembiński Z.: Aktualne kryteria oceny oraz uwarunkowania jakości nasienia knura. [Current criteria and conditions influencing the quality of boar semen]. Medycyna Wet. 1999, 55, 436 - 439. [in Polish].

5. Dubiel A.: Wpływ chlormadinonu i zabiegów operacyjnych na odruchy płciowe i ejakulaty knurów. [The influence of chlormadinone and surgery on sexual reflexes and ejaculates in boars]. Zesz. Nauk. AR Wrocław. 1977, Rozprawy nr 4. [in Polish].

6. Dubiel A., Stańczyk J.F., Króliński J., Fronczek T., Furmański K., Ciszewski J.: Flora bakteryjna ejakulatów knurów. [Bacterial flora in ejaculates of boars]. Medycyna Wet. 1981, 37, 486 - 488. [in Polish].

7. Pejsak Z.: Choroby zakaźne związane z rozrodem świń. [Infectious diseases connected with swine reproduction]. In: Wierzbowski S. (Eds.), Andrologia [Andrology], Platan, Kraków 1996, s. 217 - 246. [in Polish].

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Roland Kozdrowski
Department and Clinic of Obstetrics,
Ruminant Diseases and Animal Health Care,
Wrocław University of Environmental and Life Sciences, Poland
Plac Grunwaldzki 49, 50-366 Wrocław, Poland
tel. (+48) 71 3205313
email: rkozdrowski@wp.pl

Zdzisław Staroniewicz
Department of Pathology,
Physiopathology, Microbiology and Forensic Veterinary Medicine,
Agricultural University of Wrocław, Poland
C.K. Norwida 31, 50-366 Wrocław, Poland

Andrzej Dubiel
Department and Clinic of Reproduction,
Ruminants Diseases and Animal Health Protection,
Agricultural University of Wrocław, Poland
Plac Grunwaldzki 49, 50-366 Wrocław, Poland

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