Evaluating the use of ultrasonography with Doppler to assess peripubertal development and predict breeding soundness examination classifications in ram lambs

The objectives were to evaluate changes in testicular characteristics of peripubertal rams and determine their association with breeding soundness examination (BSE) classifications. We hypothesized that testicular echotexture and blood flow assessed via ultrasonography with Doppler would predict subsequent BSE classifications. Ram lambs (n = 40) were examined on intake for performance testing in May. In May and June, scrotal circumference (SC) and scrotal skin temperature measurements were obtained. Additionally, ultrasonography with Doppler was used to calculate total testicular volume (TTV), assess pixel intensity, and measure resistive (RI) and pulsatility (PI) indices of the right testicular artery. Rams underwent BSE ~ 10 weeks after the initial evaluation and either passed or failed based on SC and sperm quality. SC, TTV, and pixel intensity increased between May and June, whereas RI and PI decreased (p < 0.01). SC and scrotal skin temperature were greater (p = 0.03) for rams with an ‘excellent’ BSE classification than those that failed. SC was also positively correlated (r = 0.53; p < 0.01) with percent normal sperm at BSE. Testicular pixel intensity, RI, and PI did not differ (p ≥ 0.28) based on BSE classification. Decreased (p = 0.01) heart rates on intake in May were reported in rams with ‘excellent’ BSE classifications and associated with greater percent normal sperm (r = 0.42; p = 0.01) at BSE. In conclusion, ultrasonography with Doppler can be useful for assessing peripubertal development in ram lambs but provided limited capability in predicting BSE classification.