|
Description:
|
Accurate measurement of stallion spermatozoal concentration is important to
equine breeding operations . The hemacytometer is considered the standard for
measuring spermatozoal concentration but is time consuming and may be imprecise . The
flow cytometer is considered precise and accurate , but only practical for research
purposes due to sample preparation time and high cost . Photometric systems are
commonly used but can be inaccurate outside a relatively narrow concentration range
and can be rendered inaccurate in the presence of contaminants . A new instrument , the
NucleoCounter SP -100 is reported to enumerate spermatozoa at wider concentration
ranges and can identify spermatozoa in opaque semen extenders . Epididymal , neat (raw )
ejaculates , and ejaculates diluted in various semen extenders were analyzed with the
NucleoCounter , the Densimeter , the Spermacue , flow cytometric and
hemacytometric methods . Results were compared statistically by : 1 ) regression analysis ,
2 ) the agreement of two instruments , whereby the difference in values between two
instruments was plotted on the y -axis against the mean of those values on the x -axis [26] and 3 ) a modified method that measured the percentage deviation , whereby the
percentage (of the difference in values between two instruments divided by the mean ) of
the same two values was plotted on the y -axis against the mean value of the two
instruments on the x -axis .
The NucleoCounter showed more agreement with both the flow cytometer and
hemacytometer for epididymal , neat ejaculated and extended spermatozoa over a range
of concentrations than the Densimeter or the Spermacue . The NucleoCounter showed
more agreement with the flow cytometer for epididymal and neat ejaculated spermatozoa
and more agreement with the hemacytometer for spermatozoa diluted in semen
extenders . The Spermacue showed the least agreement with both standards for all
spermatozoal comparisons . All coefficients of variation for the flow cytometer ,
hemacytometer and NucleoCounter were >10 % for all spermatozoal comparisons .
This study indicates that the NucleoCounter shows more agreement with the flow
cytometer and hemacytometer than photometric systems when evaluated with
epididymal , neat ejaculated and extended spermatozoa . The instrument is also more
repeatable than either photometric system , but may be cost -prohibitive for some
operations . |