Integridade cromatínica e morfometria das cabeças espermáticas e suas relações com a concepção em éguas

Abstract

The evaluation of sperm chromatin and morphometry has gained relevance for diagnosing subfertility in stallions, especially when conventional seminal parameters do not explain reproductive failures. This study investigated whether changes in chromatin compaction, detected by Toluidine Blue, Feulgen Reaction, and Acridine Orange, as well as computational sperm head morphometric variables, correlate with conception in mares inseminated with fresh or cooled semen. Additionally, sperm morphometry was compared between Quarter Horse and Mangalarga stallions in order to evaluated possible differences between breeds and whether there was a correlation with conception. Ninety-seven semen samples used for artificial insemination were analyzed, and at least 150 sperm heads per sample were examined for chromatin compaction and morphometric variables. Chromatin characteristics evaluated showed no significant correlation with conception, indicating low sensitivity of these smear methods to predict reproductive performance when ejaculates meet minimum quality standards. In contrast, morphometric variables showed a significant correlation, with the width/length ratio (r= -0,226; p= 0,0398) and ellipticity (r= 0,226; p= 0,0400) standing out, in addition to a moderate correlation for form factor (r= -0,211; p= 0,0556) and Fourier 0 (r= 0,172; p= 0,1210). Significant differences were also observed between breeds, although these did not impact conception rates. The results indicate that, while the evaluated chromatin methods are not effective predictors, computational sperm head morphometry shows potential as a complementary objective tool for estimating stallion fertility.