Suitability of epididymal and testicular ultrasonography and computerized image analysis for assessment of current and future semen quality in the ram

Abstract

Breeding soundness evaluation (BSE) is the primary assessment for determining the reproductive potential of male animals. This method, however, cannot be used to evaluate semen frequently or to predict future semen quality. Computerized analysis of ultrasonographic images provides information on histophysiological changes in male reproductive organs. We hypothesized that: (i) semen parameters would correlate with ultrasonographic characteristics of the distal region (cauda) of the epididymis and (ii) testicular ultrasound images and/or circulating testosterone concentration would predict future semen quality in the ram. Six adult rams underwent BSE and scrotal ultrasonography approximately 60 d apart (average duration of the spermatogenic cycle) both during the breeding (December and February) and non-breeding (June and August) seasons. An inverse correlation was found between pixel intensity (numerical pixel values) of the epididymes and percentage of sperm in semen with normal morphology (r = -0.46, P < 0.05). Pixel heterogeneity (standard deviation of pixel values) correlated negatively with percentage of sperm with normal morphology (r = -0.42, P < 0.05) and directly with percentage of spermatozoa with abnormal tails (r = 0.43, P < 0.05). Pixel heterogeneity of testicular parenchyma obtained approximately 60 d prior to semen evaluation inversely correlated with percentage of sperm with normal morphology (r = -0.73, P < 0.01) and sperm progressive motility (r = -0.76, P < 0.01), and directly with percentage of sperm with abnormal tails (r = 0.72, P < 0.01) and loose heads (r = 0.79, P < 0.01). We concluded that scrotal ultrasonography combined with computer-assisted analyses of epididymal and testicular echotexture in the ram was a valuable method for determining certain current and future semen parameters, respectively.

Canine reproductive ultrasound examination for predicting future sperm quality

“…Furthermore, relationships between testicular artery blood flow are likely to relate more to current, rather than future, semen quality because endothelial thickening and changes in blood flow occur secondarily to testicular disease (Pinggera et al., ), while primary restriction of testicular artery diameter results in rapid testicular changes (Kay et al., ). It was somewhat surprising that in the present study, no association was found between testicular parenchymal heterogeneity and subjective appearance of the testicular parenchyma and subsequent semen quality, because this has been observed in rams (Ahmadi et al., ). Interestingly, Ahmadi et al.…”

“…Interestingly, Ahmadi et al. () found stronger associations between epididymal echotexture and future semen quality than they did between testicular echotexture and future semen quality. This is perhaps unsurprising given the function of the epididymis as a sperm storage reservoir and site for final sperm maturation, but importantly the study of Ahmadi et al.…”

“…This is perhaps unsurprising given the function of the epididymis as a sperm storage reservoir and site for final sperm maturation, but importantly the study of Ahmadi et al. () investigated semen quality 60 days after ultrasound examination; an interval spanning one spermatogenic cycle length. It is plausible that in the present study, the method of calculating mean semen quality throughout the 6‐month monitoring period (spanning 1–3 spermatogenic cycles [Soares, Avelar, & França, ]) masked subtle changes in semen quality, although semen quality did decline in 26 of the 55 dogs across the two studies.…”

“…In these and other studies (Zelli, Troisi, Ngonput, Cardinali, & Polisca, ), measurements have generally been related to semen quality close to the time of ultrasound examination rather than future semen quality as would be expected based upon the time taken for spermatogenesis and sperm maturation. Interestingly, in a limited number of studies in other species, some associations between the ultrasonographic appearance and future semen quality have been established (Ahmadi et al., ; Arteaga, Barth, & Brito, ; Brito, Barth, Wilde, & Kastelic, ). Indeed, Arteaga et al.…”

Biometric Indicators, Testicular Parameters and Semen Characteristics in Peripubertal and Postpubertal Pleven Blackhead Rams

“…The strong positive correlation (r=0.92; P<0.05) between testicular echogenicity and pixel heterogeneity supported the previous suggestions for use of both indicators in the assessment of the sexual maturity and the reproductive capacity in rams. In this regard, a pixel heterogeneity of testicular parenchyma obtained approximately 60 d prior to semen evaluation correlated inversely with percentage of the sperm cells with normal morphology and progressive motility, and directly with percentage of the sperm cells with abnormal tails and loose heads (Ahmadi et al, 2012). They concluded that scrotal ultrasonography combined with computer-assisted analyses of epididymal and testicular echotexture in rams was a valuable method for determining future semen parameters.…”