Individual variation related to testicular biometry and semen characteristics in collared peccaries (Tayassu Tajacu Linnaeus, 1758)

The aim of this research was to study the individual variation with regard to the morphometry of the testes evaluated by ultrasonography and semen characteristics and to verify the existence of relationship between these variables in collared peccaries. In addition, the testes of the animals were evaluated by histology in order to determine the proportion occupied by the seminiferous tubules. A total of 52 ejaculates were obtained from ten adult specimens that had been restrained by anesthesia. The testicular measurements (length, height, and width) were performed by ultrasonography, and the testicular volume was calculated according to Lambert's formula. The scrotal circumference was measured by encircling the thickest portion of the testicle with a graduated nylon tape. The semen was collected by electroejaculation. Testicular fragments were analyzed through classic histology for the determination of the area occupied by the seminiferous tubules. The results show a great amount of individual variation with regard to testicular morphometry and semen characteristics. No significant correlations were obtained between testicular measurements and semen characteristics. The histometric analysis revealed that 67.8% of the testes are occupied by seminiferous tubules. Results show that the measurement of testicular dimensions does not serve as an indicator of the quality of semen obtained by electroejaculation in collared peccaries, as there is no correlation between testicular morphometry and semen characteristics in this species that presents large variations among individuals.