view - Department of Reproduction, Obstetrics and Herd Health
view - Department of Reproduction, Obstetrics and Herd Health
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CHAPTER 1.2<br />
<strong>of</strong> a stallion stored for 24h at either 5°C or 20°C gave an identical pregnancy outcome, however, all<br />
motility parameters tested decreased significantly more when stored at 20°C in comparison with<br />
storage at 5°C (Varner et al., 1989). Storage using a synthetic extender like HGLL-BSA, is preferably<br />
done at 15°C under aerobic conditions (Magistrini et al., 1992), which was confirmed by Battelier et<br />
al. (1997) for HGLL-NPPC. Semen preserved in HGLL-NPPC at 15°C under aerobic conditions showed a<br />
markedly better motility compared to storage at 4°C under anaerobic conditions. In a more recent<br />
study (Chanavat et al., 2005), semen storage at 15°C in INRA96 resulted in lower in vitro quality,<br />
whereas fertility in vivo was the same as compared to storage at 4°C. When using EquiPro as defined<br />
extender, no difference was present for semen stored under aerobic or anaerobic conditions, nor at<br />
15°C nor at 5°C. The latter temperature, however, resulted in a better motility for samples stored up<br />
to 3 or 4 days when no antibiotics were added to the extender (Price et al., 2008).<br />
38<br />
The storage <strong>of</strong> equine semen at 15°C in INRA96 under aerobic atmosphere did not only result<br />
in an excellent motility in vitro, it also yielded good in vivo fertility results, even after long term<br />
storage (72h) at this temperature. In fact, it was better when compared to storage at 4°C in INRA82<br />
(Battelier et al., 1998).<br />
1.2.3. Transport <strong>of</strong> semen<br />
As described above, the ideal temperature for preserving equine semen might differ<br />
depending on the type <strong>of</strong> extender used. Semen is generally best preserved at 4-5°C in anaerobic<br />
conditions using any extender, mainly skimmed milk extenders, except when using INRA96, storage<br />
at 15°C in aerobic conditions is preferable. A wide variety <strong>of</strong> passive cooling devices, for cooling <strong>and</strong><br />
storage to 4-5°C, is available. These devices have variable cooling rates since the cooling process<br />
slows down as the internal temperature is reduced (Brinsko et al., 2000b). The Equitainer I <strong>and</strong> II<br />
are the best known passive cooling devices for gradual slow cooling <strong>and</strong> transport <strong>of</strong> equine semen.<br />
A first version <strong>of</strong> the Equitainer, made by Douglas-Hamilton et al. (1984), was highly successful in<br />
obtaining a slow cooling curve leading to a plateau at a constant temperature <strong>of</strong> 5°C. Furthermore,<br />
the Equitainer is extremely durable <strong>and</strong> designed for reuse. However, the initial cost <strong>of</strong> the shipping<br />
container <strong>and</strong> the inevitable charges for return shipping, are the major disadvantages <strong>of</strong> this device.<br />
Other systems, which are disposable <strong>and</strong> cheaper, are available as well (Fig. 11). All <strong>of</strong> these systems<br />
fail under extreme temperatures in keeping the samples at 4-5°C, however, most <strong>of</strong> them provide an<br />
adequate protection when the container is kept at 22°C. A higher ambient temperature might<br />
influence the core temperature <strong>of</strong> the sample, nevertheless, in vitro semen characteristics are not<br />
affected in most systems. Lower temperatures might be more cumbersome, especially if they are