Reproductive biology of Pêga Jackasses: characteristics of sperm-rich fraction collected using the split-ejaculate method

Abstract

The aim of this study was to evaluate the physical and morphological characteristics of the sperm-rich fraction of jackass semen. To this end, 130 ejaculates from five Pêga jackasses were collected using an open model artificial vagina. The sperm-rich fraction was collected using the split-ejaculate method and assessed for the number of mounts/ejaculate, for physical and morphological characteristics of the semen and number of doses produced/ejaculate. It was observed that all characteristics evaluated differed among the five jackasses, except for the head defect rates. The mean values obtained for the jackass sperm-rich fraction collected were: number of mounts/ejaculate -1.27; semen volume -20.21mL; motility -84.53%; vigor -4.46; motility after dilution -80.10%; sperm concentration/mL -894.38 x 10 6 ; total sperm/ejaculate -16.14 x 10 9 ; number of insemination doses/ejaculate (400x10 6 motile sptz) -33.39; number of insemination doses/ejaculate (800 x 10 6 motile sptz) -16.69; and percentage of normal sperm -90.46%. Thus, in the present experiment the split-ejaculate method using an open artificial vagina worked well with the jackasses, and the sperm-rich fraction of the ejaculate of Pêga jackasses had high quality and sperm concentration, allowing its use for semen processing without reducing the number of insemination doses produced per ejaculate.Keywords: jackass, split-ejaculate method, sperm-rich fraction /ejaculado -1,27; volume de sêmen -20,21mL; motilidade -84,53%; vigor -4,46; motilidade pós-diluição -80,10%; espermatozoides/mL -894,38 x 10 ; , espermatozoides/ejaculado -16,14 RESUMO Foram coletados 130 ejaculados de cinco jumentos da raça Pêga, utilizando-se vagina artificial modelo aberta, com o objetivo de se avaliar as características físicas e morfológicas da fração rica em espermatozoides do ejaculado de asininos. Para tal, a fração rica em espermatozoides, composta pelos três primeiros jatos ejaculados, foi coletada e avaliada quanto ao número de montas/ejaculado, quanto às características físicas e morfológicas do sêmen, bem como quanto ao número de doses inseminantes produzidas/ejaculado. Observou-se que todas as características avaliadas diferiram entre os cinco reprodutores avaliados, com exceção do percentual de defeitos de cabeça. Os valores médios obtidos da coleta da fração rica do ejaculado de jumentos foram: número de montas