Correlação entre características reprodutivas, ambiência e hemodinâmica testicular em touros nelores

Abstract

Ultrasonography (US) is widely used in the reproductive evaluation of large animals because it is a non-invasive technique. However, it is not routinely used in bovine andrology, resulting in gaps in studies on testicular blood flow. The present study aimed to correlate reproductive characteristics and environmental conditions based on the values obtained through color Doppler ultrasonography. The project was carried out at a bovine semen collection and processing center in Delta, Minas Gerais, Brazil, using 13 Nelore bulls aged between 18 and 36 months, randomly selected and examined by ultrasonography in both testicular parenchymas, while the pampiniform plexus was evaluated exclusively in the left antimere. The Doppler pulse repetition frequency (PRF) was standardized at 1.2 kHz, as well as the evaluation site (pampiniform plexus), probe angle (45°), and the number of waveforms generated for analysis (3). Testicular morphological parameters were analyzed through physical examination, followed by B-mode and color Doppler ultrasonographic evaluation to identify possible alterations. The correlations found demonstrated significant results, with a positive correlation observed between age and scrotal circumference (r = 0.78; p = 0.0014), ejaculate volume and age (r = 0.66; p = 0.01), scrotal circumference (r = 0.63; p = 0.01), Resistive Index (RI) (r = 0.61; p = 0.02), and Pulsatility Index (PI) (r = 0.65; p = 0.01). Sperm concentration was correlated with initial motility (r = 0.73; p = 0.004), and testicular mediastinum thickness was correlated with parenchymal echogenicity (r = 0.75; p = 0.0043). There was also a correlation between ambient temperature and relative humidity (r = -0.57; p = 0.03). Hemodynamic indices RI and PI were correlated with sperm concentration (r = 0.55; p = 0.04 and r = 0.56; p = 0.04) and with the number of frozen semen doses (r = 0.70; p = 0.007 and r = 0.75; p = 0.002), in addition to a strong association between each other (r = 0.99; p < 0.0001). Thus, since changes in environmental temperature may alter the testicular hemodynamics of bulls, compromising the spermatogenesis process, the use of color Doppler ultrasonography emerges as a complementary tool in the andrological evaluation of bulls in order to correlate the findings with their productive capacity.