Andrology laboratory review: Evaluation of sperm concentration

This article is the result of the work of the andrology task-force of the Association of Applied Animal Andrology, American College of Theriogenologists, European College of Animal Reproduction, Society for Theriogenology, and National Association of Animal Breeders. It is intended to serve as a comprehensive reference on methods to evaluate sperm concentration and to contribute to the adoption of best practices in veterinary andrology laboratories. The information covered in the article includes sample preparation and the use of manual counts, spectrophotometers, computer-assisted semen analysis, NucleoCounter, and flow cytometry. Emphasis is given to the principles of the methods and equipment, performing the evaluation, and common mistakes and/or pitfalls. In addition, the precision and accuracy of the different methods are also discussed.