Applications and interpretation of computer-assisted sperm analyses and sperm sorting methods in assisted breeding and comparative research

Abstract

Theoretical and practical knowledge of sperm function is an essential requirement in almost every aspect of modern reproductive technology, if the overarching objective is the eventual production of live offspring. Artificial insemination (AI) techniques depend on the availability of high quality semen, whether fresh, diluted and stored, or frozen. Assessing such semen for quality and the likelihood of fertility is therefore also important, as much time, resources and effort can easily be wasted by using poor samples. Some semen technologies are aimed not at quality assessment, but at attempting to skew the breeding outcomes. Sex preselection by separating the male- and female-bearing spermatozoa using flow cytometry is now practised routinely in the agricultural industry, but speculatively it may eventually be possible to use other genetic markers besides the sex chromosomes. A moment's reflection shows that although sex-biasing flow cytometry technology is well developed and generally fulfils its purpose if presorting of sperm quality is adequate, other technologies aimed specifically at semen assessment are also sophisticated but provide inadequate data that say little about fertility. This is especially true of instrumentation for objective sperm motility assessment. Here we aim to examine this technological paradox and suggest that although the sperm assessment equipment might be sophisticated, the shortcomings probably lie largely with inappropriate objectives and data interpretation. We also aim to review the potential value and use of sperm sexing technology for non-domestic species, arguing in this case that the limitations also lie less with the technology itself than with the applications envisaged. Finally, the potential application of a sorting method directed at motility rather than sperm DNA content is discussed.

Considerations of viscosity in the preliminaries to mammalian fertilisation

“…Modern estimates of sperm motility in mammals, made for the purposes of quality control or fertility prediction, use optical or laser-tracking technology to analyse cell movement within a semen sample diluted in a physiological medium [1][2][3]. Although such an in vitro approach is valuable in both a human and veterinary context, it fails to take account of the varied conditions encountered by a sperm cell during passage along the female tract.…”

Subpopulation pattern of eel spermatozoa is affected by post-activation time, hormonal treatment and the thermal regimen

“…Second, we aimed at taking 76 into account the within-sample heterogeneity that CASA data conveys, using the median values (not the 77 means, very sensitive to extreme values) for studying more reliably the kinematic parameters. 78Moreover, we have taken advantage of the potential of CASA data (Holt et al, 2007), classifying 79 the spermatozoa within each sample according to their kinematic characteristics. This requires 80 multivariate techniques such as cluster analysis (Martínez-Pastor et al, 2011).…”

Effect of milk replacer and rumen inert fat on growth and reproduction of Malpura ram lambs

“…CASA provides rapid, precise and validated objective sperm motion characteristics and has been applied in our laboratory for ram lamb semen (Kumar et al, 2010). Developments in CASA technique have shown that it provides powerful insights into sperm function and semen heterogeneity (Holt et al, 2007). Sperm velocity and motility are among the most important essential parameters in the examination of sperm quality and in the establishment of a correlation between sperm quality and fertility (Vestergen et al, 2002).…”