Comparative study between the hemocytometric and spectrophotometric methods for measuring the sperm concentration of young Nelore bulls

Abstract

Determination of sperm concentration using the Neubauer chamber (hemocytometric method) is a direct method for counting cells and also the most reliable. However, the process is time-consuming rendering it the least practical method when large numbers of ejaculates need to be processed. The spectrophotometer measures sperm concentrations as optical density and its main advantages are practicality and speed. This paper aimed to compare the results between evaluators using the hemocytometric method and the spectrophotometer for measuring sperm concentrations in young Nelore bulls. In total, 73 ejaculations from 20 young Nelore bulls were collected by electroejaculation. After soundness examination, 10 µL of the semen was diluted in 2 mL saline formaldehyde for measuring the sperm concentration per mL by the hemocytometric method (measured by three different evaluators) and the spectrophotometer method at 550 nm wavelength. No differences were detected in the results of sperm concentration measurements per mL among the evaluators using the hemocytometric method and the spectrophotometer (P > 0.05). The intraclass correlation was high (0.9), showing high replicability among the evaluator measurements. These results demonstrate that measurements performed using the spectrophotometer are reliable and can substitute the hemocytometric method in future for performing sperm concentration measurements in young Nelore bulls, thus improving and standardizing the techniques used in andrology laboratories.