Precision of the Neubauer Hemocytometer in Quantifying Concentration of Canine Spermatozoa Within and Between Operators of Differing Experience Levels

The importance of measuring accurately and precisely the concentration of spermatozoa in semen is increasing as artificial insemination becomes widely practiced in veterinary medicine. This study tested the precision of the Neubauer hemocytometer with canine spermatozoa of varying concentrations within and between operators of different experience levels (Figure 1). We calculated the standard deviation in estimates of spermatozoa concentration between two chambers of each hemocytometer and between replicate samples from the same ejaculate for both an experienced operator and an inexperienced one. The Neubauer hemocytometer precision was also evaluated across varying concentrations of spermatozoa. We determined that the operator’s experience level did not have a significant effect on precision when using the Neubauer hemocytometer. For both the experienced and inexperienced operator, the standard deviations between the two chambers of the hemocytometer and between replicate samples were 10.22 (±1.22) million spermatozoa and 10.33 (±2.16) million spermatozoa, respectively. Both these deviations exceeded 10 million spermatozoa, which many veterinarians consider to be significant when calculating a semen dosage for artificial insemination. However, this degree of deviation was present within the estimates of both operators, implying that it was not an effect of operator experience or expertise, but rather an inherent risk in using the hemocytometer.