**4. Concluding remarks**

Conventional, currently methods used in sperm quality assessment are unsatisfactory to correctly predict sperm fertility potential and do not provide sufficient information for diag‐ nosing and overcome some clinical infertility situations. The major advantages of biomarker approach over conventional semen analysis are the proficiency to accurately measure bio‐ marker levels and to expose hidden sperm defects, which go undetected during current sperm morphology assessment. Newer, unconventional diagnostic tests of sperm function have the increased potential to deliver relevant information and to have an effective predic‐ tive role in male reproductive medicine. In the present work, several molecular markers have been presented for each of the sperm functions. Some are already used in human an‐ drology, but are less used for the animals. Its use allows an increased efficiency in the identi‐ fication of infertile individuals or to predict the sperm behaviour to manipulation, hence predicting the degree of damage to be expected for a given sperm sample. The development of test based on predicted sperm functions such as capacitation and in particular sperm–oo‐ cyte interaction will present increasing impact on the field of extenders research, as well as of semen banks implementation for both domestic and wild species. It is of utmost interest the characterization of a particular biomarker patterns/levels in fertile and infertile samples, with the subsequent ability to identify males with superior tolerance to semen cryopreserva‐ tion. Nevertheless, putative molecular markers that may be used for sperm quality assess‐ ment were not exhausted in this review. Further efforts must be focused on understanding how these biomarkers correlate with transient impairments of male infertility caused by heat stress, malnutrition, diseases or trauma. Finally, the adjunctive evaluation of spermato‐ zoa functions is particular important when considering sperm storage.
