Exploring novel approaches for fertility and subfertility prediction in dromedary male camels (Camelus dromedarius)

Dromedary bulls exhibit particularly suboptimal semen quality. In this species, standard breeding soundness evaluation (BSE) often cannot catch the subtle difference between fertile and subfertile males. Therefore, the aim was to explore novel diagnostic tools to predict fertility and recognize subfertility in dromedary bulls. We explored the relationship between semen quality, fertility, echotexture parameters, accessory glands volume and total testosterone. Two sets of experiments were performed: in vitro (semen group) and in vivo (natural mating group). Each group was assessed by standard BSE: clinical examination, testis volume, ultrasound analysis of testicular parenchyma (TP) and epididymis. For the first time, images of epididymal head were obtained. Testis volume was not correlated to any parameters studied. Ultrasound TP showed especially low sensitivity (20 % in vitro and 14 % in vivo). The standard BSE was found unsuccessful in assessing subfertility. Therefore, animals were then submitted to advanced BSE: digital image analysis of TP, assessment of accessory glands (prostate (P) and bulbourethral (BB) glands) and serum total testosterone concentration. Upon analysis, significant correlations were found among some echotexture parameters (white pixels, mean grey levels, area and density of hypoechogenic areas) and percentage of viability, head defects, mitochondria potential and fertility. Only white pixels showed strong sensitivity (86 %) and specificity (100 %). BB volume correlated with ejaculate volume. Total testosterone concentration did not correlate with any parameters studied. In conclusion, advanced BSE (digital ultrasound image analysis and accessory glands volume) proved to be a useful tool for predicting semen quality and detecting subfertility in dromedary camels.