Seasonal variation in testicular biometry of wild boar in the game preserve

Abstract. The increase in wild boar numbers in recent decades is partly due to the involvement of most young females in reproduction as early as their first year of life. After the rut of adult females is over, young females are still entering oestrous as they attain maturity, prolonging the rutting period by several months. This study aimed to evaluate the effect of seasonality on the growth rate of male wild boar bodies, the growth of piglet and yearling male wild boar gonads, and sperm concentration in the epididymides. We found that yearlings' weight and body length were almost constant in summer and autumn, with a sharp increase in winter. Seasonality was also reflected in the body condition index, which rose by more than 41% between summer and winter. In terms of seasonality, the testimetric dimensions again differed significantly only in winter. Sperm were recorded in piglets weighing more than 15 kg. Regardless of the time of capture, 41% of piglets were examined as juveniles, only 6%, resp. 8% of piglets reached low or medium concentration values. While 10% of all yearling males were azoospermatic (juvenile), regardless of weight, there was evidence of seasonality in the proportion of males with measurable concentrations. These concentrations gradually increased from 62.5% in summer to 78.6% in winter. No sterile male over two years of age was noted. The results show that even in wild boars, there is a culmination not only of physical characteristics in winter but also a culmination of testimetric dimensions. Sperm already occur in 15 kg of piglets, which means they can theoretically participate in the fertilisation of female piglets.