Seasonality analysis on cryopreserved doses from the autochthonous cattle breeds Asturiana de la Montaña and Asturiana de los Valles.

Germplasm banking is a fundamental tool for the preservation of autochthonous breeds. Semen cryopreservation is effective for this task, but protocols are adapted to commercial species, and post-thawing sperm quality could be sensitive to environmental cues. We compared the post-thawing sperm quality in doses from the CBA-SERIDA bank in northern Spain for the Asturiana de la Montaña (AM) and Asturiana de los Valles (AV) autochthonous cattle breeds. Doses from 23 AM and 16 AV bulls (ejaculates from at least three different seasons) were assessed for motility (computer-assisted sperm analysis), physiology and chromatin status (flow cytometry) after thawing and after 5 h at 38°C. Data were analysed using linear mixed-effects and cosinor models for seasonal and breed effects and by correlations with the association of sperm quality with temperature-humidity index (THI), considering the interval of spermatogenesis plus maturation. The breed affected sperm quality, with higher motility for AV and higher apoptotic ratio, mitochondrial activity, reactive oxygen species, DNA fragmentation and chromatin immaturity for AM. However, seasonality effects were minimal, and THI was not associated with sperm quality. In summary, the season seems to be a minor factor in the post-thawing quality of the AM and AV autochthonous breeds, well-adapted to their local environment.