Daily variations in AQP3 relocation and sperm cryoresistance in wild and domestic goats

Abstract

This study aimed to evaluate daily variations in sperm quality, testosterone levels, cryoresistance, and the relocation of AQP3 in plasma membrane domains in wild and domestic goats. Samples were collected from five Murciano-Granadina bucks and seven Iberian ibex at 12:00 h (noon) and 00:00 h (midnight), during the rutting season. Sperm motility, viability, acrosome integrity, DNA fragmentation, and immunolocalization of AQP3 were assessed in fresh and frozen-thawed semen samples. Serum testosterone concentrations were also determined at both times. In domestic goats, kinematic parameters were greater (p < 0.05) in semen collected at midnight, whereas the cryoresistance ratio was greater (p < 0.05) for these variables in semen recovered at noon. In ibexes, fresh semen collected at midnight was greater (p = 0.05) for VCL, VSL, VAP, and ALH values. After freezing-thawing, a significant increase in AQP3 labelling at the acrosomal region was observed in samples collected at midnight for both species, as well as in samples collected at noon for bucks (p < 0.05). An increase in the proportion of spermatozoa with AQP3 labelling in the mid-piece was detected in bucks in frozen-thawed samples collected at noon (p < 0.05). Testosterone concentrations were higher (p < 0.05) at midnight in bucks but no differences were found in ibexes. The findings reveal daily variations in sperm quality in both domestic and wild goats, which do not exactly coincide with the daily changes in cryoresistance, thus calling for attention when processing semen.