Extender and centrifugation effects on the motility patterns of slow-cooled stallion spermatozoa.

Abstract

Slow-cooled stallion spermatozoa, with and without seminal plasma removed by centrifugation, were diluted in Kenney's extender (KE) containing nonfat dry skim milk with glucose and antibiotics or in KE supplemented by adding a modified high-potassium Tyrode's medium (KMT). Four ejaculates from each of four stallions were collected and divided factorially across these four treatments. Percentage of motile sperm, path velocity, and linearity immediately after treatment (0 h) and after storage at 4 degrees C for 24, 48, and 72 h were evaluated objectively by use of a HTM-2030 sperm motility analyzer. Stallions were a significant source of variation (P less than .01) throughout. After sperm had cooled, effects of stallion, extender, centrifugation, and their interactions were all found to be significant (P less than .01). The motility at 0, 24, 48, and 72 h for centrifuged KE was 74, 47, 39, and 24%; for uncentrifuged KE was 76, 56, 50, and 37%; for centrifuged KMT was 76, 75, 72, and 64%; and for uncentrifuged KMT was 80, 50, 26, and 13%, respectively. The extender x centrifugation interaction, after 24, 48, and 72 h of storage, accounted for half or more of the variation. Whereas centrifugation of semen extended in KE seemed to be harmful to sperm, motility of sperm extended in KMT after centrifugation was remarkably conserved for 72 h and was superior to all other treatments (P less than .05). This extender is promising for preserving liquid stallion semen when it must be transported before use in artificial insemination.

Quality of Raw and of Cold-Stored Semen in Icelandic Stallions

“…The interaction of extender and centrifugation has been reported in previous studies [17,18] which demonstrate that centrifugation of semen extended with Kenney and a modified (Tyrode-medium) Kenney extender had both negative and positive effects on the motility of cooled semen. In this context, it has been speculated that by adding an extender a beneficial effect is observed through the reduction in concentration of harmful compounds, but that this effect is countered by in the electrolyte balance.…”

“…In this context, it has been speculated that by adding an extender a beneficial effect is observed through the reduction in concentration of harmful compounds, but that this effect is countered by in the electrolyte balance. This phenomenon is particularly hard to explain when using extenders composed of natural materials such as skim milk, the content of which is not clearly defined [18]. For optimal protection of cold-stored sperm it is therefore recommended to remove the majority of seminal plasma after centrifugation and to resuspend the sperm pellet with a chemically well defined extender [17].…”

Components of stallion seminal plasma and their influence on spermatozoa

“…No differences are seen in sodium or potassium concentrations between ejaculatory fractions (Kareskoski et al 2005). The addition of potassium to semen extenders improves motility of stallion (Padilla and Foote 1991) and human sperm (Karow et al 1992), but Rossato et al (2002) found no correlation between the ionic composition and the osmolarity of human seminal plasma. Intracellular concentrations of potassium are higher than those of seminal plasma, and therefore potassium levels are linked to sperm concentration.…”

“…If all seminal plasma is removed, skim milk is not a suitable extender. Addition of a modified high-potassium Tyrode's medium to skim milk extender during cooled storage of ≥24 h in the total absence of seminal plasma has yielded good sperm motility; but if any seminal plasma is left, skim milk alone is better than addition of Tyrode's medium (Padilla and Foote 1991, Webb and Arns 1995, Rigby et al 2001. The effect of seminal plasma during storage may also depend on the temperature; 5°C, room temperature and 40°C have given different results (Wöckener et al 1990, Sieme et al 2001.…”

“…Cooled storage of fresh semen requires addition of extenders, most commonly skim milk based extenders, that pro- (Jasko et al 1991, Pruitt et al 1993 In many studies, centrifugation of semen, removal of supernatant and subsequent resuspension into skim milk extender have improved sperm motility as compared to non-centrifuged samples (Palmer 1984, Jasko et al 1991, Pruitt et al 1993, Langkammer 1994, Sieme et al 2001, Todd et al 2001), but in some other studies the total removal of seminal plasma and replacement with skim milk extender has decreased motility after 24-h storage (Padilla and Foote 1991, Jasko et al 1992, Rigby et al 2001. If all seminal plasma is removed, skim milk is not a suitable extender.…”