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

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.