Compensability of Enhanced Cytoplasmic Droplet Rates in Boar Semen: Insights of a Retrospective Field Study

Retained cytoplasmic droplets (CD) provide the most abundant sperm abnormality in boar and reduce fertility. It is still unclear as to whether high CD rates in semen portions are compensable. The aim was to explore the impact of CD in relation to quantitative and qualitative sperm traits on fertility performance of sows. Retrospective data analysis of 1497 inseminations was performed. Ejaculates (n = 260) were assigned to three groups with low (<10%), medium (≥10% to <15%), and high (≥15%) CD rates. Average sperm numbers were lowest in the high CD group (2.08 × 109/mL). Membrane integrity and mitochondrial activity did not differ between the groups. Breakpoint analysis indicated a shift towards lower litter sizes when the CD rate exceeded 11%. Group comparisons revealed no difference in litter size (p = 0.205), together with a slightly higher farrowing rate in the high CD group (p < 0.001), which coincided with higher resistance against temperature stress in the stored semen samples (p < 0.001) and a higher sperm motility (p < 0.001). In conclusion, an increased prevalence of CD in boar semen is compensable by high tolerance against temperature stress, whereas sperm numbers per dose are less relevant.