Effect of refrigeration semen extender, refrigeration and storage at 4 degrees on buck semen microbiome

Ejaculates present their own microbiota and a link between the microbiota and the sperm quality and fertility has been demonstrated. In this study, we explore the effects of the protocol for the preparation of goat buck refrigerated semen doses (that include dilution with a refrigeration extender and refrigeration to 4 degrees) and of storage period at temperatures below the body temperature on the semen microbiota. For the study, semen from six adult goat bucks from the Murciano-Granadina breed (24 ejaculates) was used and refrigerated to 4 degrees using a skimmed milk-based extender, being stored at this temperature for a maximum of 24 h. Samples were taken at different steps of the preparation: in the crude ejaculates (ejaculates), after the dilution with the refrigeration extender (diluted), immediately after reaching 4 degrees (Chilled 0 h) and in samples refrigerated to 4 degrees and stored at this temperature for 24 h (Chilled 24 h). Bacterial 16S rRNA sequencing was used to study the semen microbioma in the different steps of the refrigeration protocol as well as in the extender. In addition, sperm quality (motility and integrity of plasma and acrosomal membrane, and mitochondrial functionality) were also evaluated.