Interaction among extenders, cryoprotectants and Orvus Es Paste supplementation and freezing rate for sperm cryopreservation in the dromedary camel.

This study evaluated the effects of freezing extenders, cryoprotectants and their concentrations, presence of Orvus Es Paste and freezing rates for cryopreserving dromedary camel sperm. Semen (five males; 2 ejaculates/male) was frozen in one of the following extenders (Green Buffer® or INRA96® ), cryoprotectants (3 and 6% glycerol or ethylene glycol), with or without Orvus Es Paste and freezing at two different heights (1 and 4 cm) above liquid nitrogen. Sperm motility recovery parameters were evaluated post-thaw (0 and 1 hr), vitality and acrosome integrity (0 hr). Green Buffer showed higher total motility recoveries (p < .001). Higher percentage of cryoprotectant improved both total and progressive motility at 0 hr (p < .001; p = .003) and 1 hr (p < .001; p = .005). Acrosome integrity at thawing increased in the presence of ethylene glycol (p < .001) and Orvus Es Paste (p = .001). Kinematics were affected by extender, cryoprotectant concentration and Orvus Es Paste at 0 and 1 hr, and type of cryoprotectant only influenced them at 0h. Our findings showed strong interactions among type of cryoprotectant and concentration, and extender and Orvus Es Paste. Generally, combining Green Buffer, 3%-6% ethylene glycol or 6% glycerol without Orvus Es Paste, regardless of the freezing rates, yielded the highest post-thaw parameters for camel sperm.

Identification of proAKAP4 concentration variations in dromedary sperm and their correlation with monthly semen parameters.

ProAKAP4 is synthetized as a precursor polypeptide that must be converted into mature AKAP4 in living spermatozoa and is considered as a functional marker of spermatozoa. The gene is well-conserved in mammals although uncharacterized in Camelidae. In the present study, we investigate the expression metabolism of proAKAP4 and AKAP4 proteins and evaluate their seasonal dynamics relative to semen quality in dromedary camels. Semen parameters including volume and viscosity and characteristics of sperm including concentration, total production, total and progressive motility, vitality, acrosome integrity and morphological abnormalities were assessed in semen samples collected weekly from six camels during the rutting season, from November to April. Only total sperm production varied, peaking in January. Both the precursor proAKAP4 and AKAP4 proteins were investigated and shown to express biochemical properties similar to those described in other mammals. ProAKAP4 concentrations expressed in ng/10 million spermatozoa as assayed using a specific ELISA showed a strong positive correlation with ejaculate volume (P = 0.045), viscosity (P < 0.001) and sperm total motility (P = 0.049). Furthermore, their concentrations exhibited clear seasonal variations in camel semen. In conclusion, the assessment of proAKAP4 concentrations in camel sperm provides a novel parameter to assess sperm quality. Further studies should be performed to investigate proAKAP4 concentrations relative to fertility in Camelidae that may help to define the right time for mating and semen collection and increase the success of breeding programs. LAY SUMMARY: Breeding related to the seasons/time of year in the camel has been reported in several studies. A better knowledge of semen quality during the breeding season would assist in determining the best period for mating in camels. However, conventional sperm parameters are held to be unsatisfactory because they cannot predict breeding potential. ProAKAP4 a sperm-specific protein has been described as a functional marker of sperm and a key fertility marker in several species but has not been described in camels. Motility or membrane integrity parameters of semen collected throughout the breeding season and also the presence of proAKAP4 protein were investigated. ProAKAP4 was identified for the first time in camels and their concentrations exhibited clear seasonal variations in camel semen showing strong correlations with ejaculate volume and total motility and viscosity. Further studies should be performed to investigate proAKAP4 concentrations relative to fertility in camels to define the right time for mating and increase the success of breeding programs.