The effect of stress on semen reduction in the marmoset monkey (Callithrix jacchus)

This study compared a number of semen parameters of two separategroups of the common marmoset monkey (Callithrix jacchus) inorder to determine the effect of a continuous potentially stressfulsituation on these parameters, and thus on the monkey's reproductiveability. The semen from 16 adult male marmoset monkeys was collectedand analysed to compare semen parameters between a ’normal‘(control) group (n = 9) and a ’blood withdrawn‘(’stress‘) group (n = 7). The semen parameter valuesobserved in the control were: pH 7.51 ± 0.22, volume40.2 ± 27.2 µ1, concentration 27.3 ± l4.8xl04/ul,motility 47.4 ± 15.9%, grade of velocity 3.5 ±1.2, and normal morphological forms 51.8 ± 13.7%. The’blood withdrawn‘ group of marmoset monkeys showedsignificantly lower semen volume and sperm concentration thanthe ’normal‘ group. In addition, total count ofspermatozoa, normal spermatozoa, motile spermatozoa and normalmotile spermatozoa per ejaculate per monkey was significantlyreduced in the ‘blood withdrawn’ group. The semenof these monkeys also revealed a significantly higher percentageof abnormally-shaped sperm heads than the normal group, andcases of impotence and sham ejaculation were recorded. Our studyrevealed that the continuous withdrawal of a small volume ofblood from a group of marmoset monkeys appeared to be stressfulto these monkeys and as a result, influenced their semen parameters,possibly making them less fertile. In addition, electroejaculationwas found to be possibly harmful to the monkey's reproductiveability.