view - Department of Reproduction, Obstetrics and Herd Health
view - Department of Reproduction, Obstetrics and Herd Health
view - Department of Reproduction, Obstetrics and Herd Health
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CHAPTER 5.2<br />
supernatant allowing sperm yield to be calculated. This technique <strong>of</strong> centrifugation only results in<br />
separation <strong>of</strong> the spermatozoa from the seminal plasma. Alternatively, the forces originating during<br />
centrifugation can also be used to select the superior sperm fraction from a sample when low g-<br />
forces are combined with a colloid (Chapter 4.2).<br />
5.2.1. Centrifugation to concentrate equine semen samples<br />
Much uncertainty exists on how spermatozoa react on a cellular level to centrifugation. The<br />
influence <strong>of</strong> centrifugation on sperm yields <strong>and</strong> semen characteristics is controversial as well.<br />
However, much <strong>of</strong> the variation in study results can be explained by differences in experimental<br />
design. Extender type (Cochran et al., 1984), volume per centrifugation tube (Cochran et al. 1984,<br />
Webb et al., 2009), dimensions <strong>of</strong> the centrifugation tube (Webb <strong>and</strong> Dean, 2009), <strong>and</strong> <strong>of</strong> course<br />
centrifugation time <strong>and</strong> force (Cochran et al., 1984; Weiss et al 2004; Len et al. 2008, 2010; Webb et<br />
al., 2009; Hoogewijs et al., 2010) are all factors influencing yield <strong>and</strong> quality <strong>of</strong> equine semen after<br />
centrifugation.<br />
Our findings (Chapter 4.1) on sperm yields were consistent with the general trends in<br />
literature. Using the st<strong>and</strong>ard protocol (600 × g for 10 min) 78% <strong>of</strong> the initial number <strong>of</strong> spermatozoa<br />
were maintained. Sperm quality was not influenced largely. Immediately following centrifugation<br />
motility <strong>and</strong> membrane integrity were only slightly reduced compared with non-centrifuged samples.<br />
The use <strong>of</strong> higher forces for a shorter period <strong>of</strong> time reduced sperm losses without affecting the in<br />
vitro sperm quality following cooled storage or cryopreservation.<br />
When looking at the variations in the above mentioned studies on sperm losses, it is obvious<br />
there might be a stallion effect as well. Some stallions have semen that sediments easier during<br />
centrifugation, <strong>and</strong> some have spermatozoa that are more prone to damage caused by centrifugation<br />
compared to other stallions (personal observations). So individual centrifugation protocols might be<br />
necessary for some stallions, <strong>and</strong> if corrections for sperm loss following centrifugation are made, it is<br />
important to re-assess the actual sperm number following centrifugation <strong>and</strong> not to use a fixed<br />
correction factor since sperm loss is influenced by so many parameters.<br />
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