The influence of seasonal climatic factors in the Republic of Moldova on semen production in Duroc boars under a climate-controlled system technology

Abstract

This study investigates the impact of seasonal climatic variations in the Republic of Moldova on the semen production of Duroc boars when housed under a climate-controlled management system. It has been established that despite the implementation of environmental control technologies, fluctuations in ambient conditions associated with different seasons may still influence reproductive functionalities of boars. The research analyzes semen quality and quantity indicators - including volume, concentration, motility, and total sperm output - across distinct seasons over a defined period. Results demonstrate that while climate control systems mitigate extreme environmental stress, seasonal trends continue to exert a statistically significant influence on specific reproductive parameters. Ejaculate volume showed high variability during autumn and winter (CV > 30%), which may reflect individual differences among boars. Maximum ejaculate volumes were recorded in autumn and winter, while the lowest were observed in summer. The number of doses per ejaculate exhibited high variability (CV 24 - 30%), possibly due to ejaculate quality differences or technical factors. Average values were higher in autumn (35.1) and winter (33.7), with a maximum of 71 doses per ejaculate recorded in autumn. The total sperm concentration (M/ml) was generally higher in autumn and winter, with lower coefficients of variation, indicating greater stability during these seasons. Maximum sperm concentrations were registered in spring, while the lowest values were observed in summer. Proximal droplets (%) were highest in winter (17%), though with higher variability. Spring showed the lowest variability for this trait. Distal droplets (%) were slightly higher in summer (4.8%), but showed consistently high variability (55 - 74%) across seasons. Bent tails (%) remained stable year-round, with a slight improvement in autumn–winter.

These findings underscore the need to further optimize environmental technologies and management strategies to maintain consistent boar fertility throughout the year.