In Vivo Ultrasonographic Assessment of Bone Mineral Density and Its Impact on Semen Quality in Boars

Bone mineral density (BMD) is a key indicator of skeletal health in boars that influences their reproductive performance. Systematic research on the relationship between BMD and semen quality in adult boars of different breeds and ages is scarce. This study used quantitative ultrasound (QUS) technology to measure BMD in 492 adult and 208 replacement boars. The boars were divided into four equal groups based on descending BMD rankings to analyze correlations with semen quality. Simultaneously, a 25-hydroxyvitamin D₃ (25-OH-D₃) intervention trial was conducted on 150 adult Duroc boars. A control group and four dose groups (50 μg, 125 μg, 200 μg, and 250 μg) were established. After 90 days, the boars' semen quality, reproductive hormone levels, and bone metabolism indicators were evaluated. The results showed no significant differences in BMD between adult and replacement boars. However, adult Landrace exhibited significantly higher BMD than Duroc and Yorkshire (<i>p</i> < 0.01). Within the BMD groups, Group D boars had significantly higher rates of sperm abnormality than Groups A and B (<i>p</i> < 0.01), and this trend was consistent across breeds. The 25-OH-D₃ intervention results indicated that the 250 μg dosage produced the optimal effect. In this group, boar semen motility significantly improved while sperm abnormality rates significantly decreased. Concurrently, levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), serum osteocalcin (OC), and BMD all increased to some degree. In summary, boar BMD is significantly influenced by breed and age and is closely correlated with the rate of sperm abnormality rate. Supplementing with 250 μg of 25-OH-D₃ effectively enhances reproductive hormone secretion, improves semen quality, and promotes bone formation. This demonstrates its potential value in breeding and nutritional regulation applications.