Reproductive parameters of wild boar (Sus scrofa) in three different parts of Germany

Abstract

Recent increases in wild boar populations in central Europe necessitated an evaluation of the current reproductive performance of this species. During a 2-year study, samples of ovaries and uteri were taken from wild boars from areas in the (northern) state of Lower Saxony and the (more southern) Rhineland-Palatinate, Germany, in which wild boar have been vaccinated against classical swine fever (CSF) after several outbreaks of the disease. Serum samples were also analyzed to determine the prevalence of diseases that may influence pig reproduction and fertility. While there was a striking seasonality of reproductive performance, especially among older animals, mating was delayed in up to 15% of piglets and yearlings, leading to a second peak of farrowing from June to August. Depending on the area, between 60 and 70% of the piglets were most likely to become pregnant during the main period of reproduction, while another two thirds of the remaining individuals farrowed by the summer, which was the case in the mountainous areas. The arithmetic mean number of fetuses were 6.29 per piglet, 6.67 per yearling, and 7.64 per adult for wild boar in Eastern Lower Saxony; 4.58 per piglet and 4.63 per yearling and 6.56 per adult for wild boar in the Western Eifel and 4.77 per yearling and 6.50 per adult in the Palatine Forest, as the number of pregnant piglets has been too low to calculate an arithmetic mean in this area. The numbers of Lower Saxony wild boar fetuses per individual exceed previously known values. The results indicate that exogenous factors have a strong impact on both reproductive seasonality and the percentage of reproducing individuals in an age group. Ovulation rates, numbers of fetuses, and prevalence of pregnancies were found to be high among all age groups, while early onset of puberty and high pregnancy rates were typical of young animals (yearlings). The influence of some important reproductive diseases like Aujeszky's disease, Brucellosis, porcine reproductive and respiratory syndrome, porcine parvovirosis, and CSF on wild boar reproduction and fertility was tested and found to be at least of minor interest for the reproductive outcome of the species.

Reproductive performance of wild boar females in Portugal

“…The significant differences obtained in breeding status among age classes were interrelated with the minimum body weight of sexually active females observed in our study, which is similar to those observed in Asian and other European wild boar populations (Table 4); however, the minimum body weight of sexually active females may vary according to the population structure, food availability, hunting/predation pressure and clime in wild boar populations. In fact, Gethöffer et al (2007) make refererence to piglets sexually active (15 kg) in Germany, perhaps reflecting the structure and density of the population as well as optimal enviromental conditions for this species. There is thus found to be a high percentage of nonreproductive juveniles with higher proportions of pregnant or lactating females among yearlings and adults.…”

“…Sexual maturity in females is achieved between 5 and 10 months of age, although it is assumed that a minimum body weight of 15-35 kg (e.g. Mauget and Pépin 1991;Appelius 1995;Gethöffer et al 2007), influenced by food availability, must be attained before puberty can occur (Sweeney et al 1979;Aumaitre et al 1982;Kanzaki 1991;Groot Bruinderink et al 1994). …”

Effects of a GnRH vaccine on the movement and activity of free-living wild boar (Sus scrofa)

“…It also appeared that, as previously found in bison (Miller et al 2004), GonaConÔ vaccination did not affect existing pregnancy. Farrowing in wild boar mainly occurs between February and June (Gethöffer et al 2007) and females become pregnant between December and March. Five females treated during pregnancy produced litters and at least four of these animals (one was not recaptured) also developed antibody titres that putatively should have prevented further pregnancies.…”

Edge Effect on Density Estimates of a Radiotracked Population of Yellow‐Necked Mice

“…To calculate reproductive output, we assumed a population growth rate of 250% per year which was derived from combined data on wild boar reproduction in our study area and in a similar forested habitat also situated in southwestern Germany (Getho¨ffer et al 2007). As a basis for the calculation of reproductive output, we used the Bayesian population estimate for each study year, because it seemed to be the most robust and conservative approach with our data.…”

“…To anticipate a further increase in population size, and even more to reduce the wild boar numbers, either the hunting regime will have to be changed (e.g. hunt more females of all age classes, especially piglets; Getho¨ffer et al 2007, Toigo et al 2008 or other regulatory mechanisms will have to be established (e.g. contraceptives; Massei et al 2008).…”