Use of Novel Methods to Assess Seasonal Differences in the Quality of Boar Semen Stored Up to 7 Days at 17°C

The objective of the present study was to determine the seasonal changes in boar semen quality by the assessment of sperm membrane integrity, analysis of chromatin structure, assessment of oxidative stress and of apoptotic changes in spermatozoa. Semen from 16 boars (172 ejaculates) was investigated. The males were aged between 7 months and 7 years. Semen was extended with BTS diluent and stored at +17°C. During seven days of storage, the semen was subjected to standard evaluation and novel methods for semen assessment. In the autumn-winter period, the semen had higher evaluations than in the spring-summer period, but only sperm membrane integrity examination showed significantly lower (P≤0.01) percentage of moribund spermatozoa and the semen had a significantly (P≤0.05) lower (by 0.5%) percentage of sperm with damaged chromatin. Examination performed after 7-day storage showed significantly (P≤0.01) higher percentage of live spermatozoa and with high mitochondrial membrane potential for the autumn-winter period. The level of apoptotic cells was significantly (P≤0.01) lower for the autumn-winter period. Examination of sperm membrane integrity after 7 days of storage showed a lower (P≤0.05) percentage of moribund spermatozoa for the autumn-winter period. In our opinion, novel methods for sperm assessment may be used to monitor new parameters of sperm function.