Associação entre ultrassonografia, histologia testicular e qualidade seminal para a seleção reprodutiva de varrões de alto potencial genético

Abstract

Ultrasonography is a non-invasive and promising tool for monitoring physiological changes in the testicular parenchyma throughout reproductive development. Its application, combined with objective gray-scale analysis (GSA), may support genetic improvement programs by optimizing the early selection of boars with high productive potential across different genetic lines. This study aimed to predict the reproductive potential of boars from distinct genetic lines early in life, based on ultrasonographic evaluations, growth performance, and testicular histology from birth to 370 days of age. Boars from the Landrace (LD, n = 424), Large White (LW, n = 278), Duroc (DU, n = 431), and Synthetic Terminal (ST, n = 385) lines were evaluated at different stages regarding testicular biometry and GSA parameters. Animals were subsequently allocated into two subgroups: histological evaluation (n = 39; LD = 10; LW = 9; ST = 10; DU = 10); and semen productivity assessment (n = 182; LD = 32; LW = 40; ST = 69; DU = 41). In histological evaluation, seminiferous tubule area and average diameter, volumetric proportion of testicular components, and the number of Sertoli cells per tubule were assessed. In the semen productivity assessment, boars were classified as “productive” or “non-productive” based on semen quality parameters. This was a longitudinal observational cohort study. Results showed that LD and LW boars had lower birth weights (P<0.05), while ST maintained higher body weight across all stages (P<0.05), and DU showed the least testicular development (P<0.05). Testicular biometry and GSA parameters varied significantly among genetic lines and were positively correlated with body weight (P<0.05). LD boars exhibited greater testicular weight and higher seminiferous tubule proportion, whereas DU had a greater proportion of interstitial tissue (P<0.05). Among GSA parameters, heterogeneity (HET), mean gray value (MEANGV), and standard deviation of the mean gray value (DEVOFTHEMEAN) demonstrated predictive value for semen quality, particularly at the off-test stage. It is concluded that the ultrasonographic evaluation of testicular parenchyma using GSA parameters is an objective and promising tool for the early assessment of boars. GSA parameters vary across different genetic lines and are associated with testicular histological components. Furthermore, performing ultrasonography at the off-test stage allows for the early prediction of future semen quality in males, contributing to more efficient selection strategies and the utilization of boars with high genetic merit.