Effect of seasonality on quality and fertility of cryopreserved New Zealand white rabbit semen under Egyptian conditions

Abstract

The present study was designed to investigate the effect of seasonality on the quality and fertility of cryopreserved New Zealand white (NZW) rabbit semen under Egyptian conditions. Semen was collected from fifteen mature rabbit bucks during winter, spring, summer and autumn seasons, diluted in INRA-82 extender and cryopreserved in liquid nitrogen. Following the freezing/thawing process, semen samples were evaluated for semen quality parameters. We also investigated whether seasonality could affect postthaw fertility. The results showed that semen collected and processed during winter, autumn, and spring significantly improved ( P <0.05) sperm motility (56.33, 54.12 and 54.00%, respectively), live sperm (59.24, 58.34 and 57.01%, respectively), functional membrane integrity hypo osmotic swelling test (67.34, 64.59 and 64.31%, respectively), acrosome intactness (79.25, 77.45 and 76.72%, respectively) and sperm with non-fragmented DNA (75.66, 74.02% and 72.53%, respectively) in comparison with semen collected and processed in summer season (30.24, 33.26, 42.51, 51.20 and 40.22%, respectively). The fertility results revealed that conception and kindling rates were significantly higher ( P <0.05) when semen samples were collected and processed in winter (80.00 and 76.00%, respectively) in comparison with those collected and processed in autumn (74.00 and 70.00%, respectively), spring (70.00 and 64.00%, respectively) and summer (30.00 and 20.00%, respectively). In summary, our results show that the quality and fertility of cryopreserved NZW rabbit buck semen depends on the season during which the semen is collected and processed. Moreover, for the best fertility results in doe insemination, semen collected and processed (cryopreserved) in winter season should be used.