Meta-analysis of fluorochrome concentrations to assess bull sperm quality by flow cytometry in 2021–2023

Abstract

Flow cytometry (FC) is a very powerful method for the assessment of spermatozoa quality in multiple livestock species, including bulls. Nowadays, many flow cytometric tests are available for quality detection of bull sperm. These tests are based on fluorochromes (fluorescent tags or dyes) and the use of correct concentrations of fluorochromes is an essential aspect of the successful optimization of experimental methodology. Modern flow cytometers are much more affordable, such that spermatologists are now able to use FC methodology (and even image cytometry) in their studies. The present review aims to give a summary of current flow cytometric methodologies used to assess bull sperm quality by flow cytometry. Namely, we give here the concentrations of fluorochromes used in the studies related to bull sperm quality evaluation by flow cytometry published in the last three years (from 2021 to 2023). Importantly, in the present review, the concentration of fluorochromes is unified and presented using comparable molarity units. Furthermore, the rationale of each flow cytometric methodology for particular fluorescent tests, and the citation for the corresponding original methodology, are given. This review will help spermatologists shorten the time needed for the optimization of their flow cytometry methodology for the assessment of bull sperm quality.