Effect of Refractoriness to Long Photoperiod on Sperm Production and Quality in Tomcats

Contents The aim of this study was to assess whether refractoriness to long photoperiod (LP) could be reversed by subjecting tomcats to a period of short days. Our hypothesis was that photoperiod changes can avoid refractoriness and restore sperm quality and production to that before refractoriness. Tomcats (n=6) were housed in a conditioned room with LP (12L: 12D) for 45days of acclimation and then maintained under LP for 18month. Then, tomcats were changed to a period of decreasing light at a rate of 8min/day for 1month. Tomcats stayed for 1month with short photoperiod (SP; 8L: 16D) and then were switched back to a period of increasing light at a rate of 8min/day for 1month. The experiment was completed after tomcats remained in LP for 2months. Toms were anaesthetized and semen samples were collected by electroejaculation every 2weeks. Sperm parameters were evaluated in all ejaculates, and data were analysed by anova. Motility, velocity, volume, sperm concentration, total sperm count, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher during LP compared with a refractory LP (p<0.01). Likewise, velocity, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher in a LP compared with a SP (p<0.05). On the other hand, motility, volume, concentration and total sperm count were similar between LP and SP (p>0.20).Whereas motility, velocity, viability, acrosome integrity and plasma membrane integrity were similar in a refractory LP compared with SP (p>0.05), volume, sperm concentration, total sperm count and sperm morphology were lower in a refractory LP compared with SP (p<0.05). In conclusion, refractoriness and reduced sperm production and quality induced by a prolonged LP of 18month can be restored after placing tomcats to a SP.