The present results for the WS-M group show that the insertion of melatonin implants in December-February-April also prevents seasonal reductions in scrotal circumference and in the percentage of sperm showing non-progressive motility, and improves acrosome integrity in the spring when compared with control group. These results suggest that lengthening the short day period afterthet winter solstice extends reproductive activity in Ibex,as it does in less seasonal ewes