Cryopreservation of Boar Semen in Mini‐ and Maxi‐Straws

Abstract

Split ejaculates from four boars were frozen with a programmable freezing machine, in mini-(0.25 ml) and maxi-(5 ml) plastic straws with an extender at either acidic (6.3) or alkaline (7.4) pH. Glycerol (3%) was used as cryoprotectant. The freezing of the semen was monitored by way of thermocouples placed in the straws. Post-thaw motility and acrosome integrity were evaluated; the latter using phase contrast microscopy, eosin-nigrosin stain and electron microscopy. Post-thaw sperm motility was significantly higher when semen was frozen in mini-straws than in maxi-straws. For the mini-straws, the motility was better when semen was exposed to an acidic environment during freezing, but this beneficial effect of the low extracellular p H was not evident when maxi-straws were thawed. The motility of the spermatozoa diminished significantly during the thermoresistance test (0 h and 2 h time) at 37°C in a similar way for both straws and extracellular pH's. The freezing procedure, no matter the extracellular pH, did not cause major acrosomal damages, but significantly more normal apical ridges were present in the mini-straws than in the maxi-straws. This in vitro evaluation indicated that the freezing method employed was better for mini-than for maxi-straws since the freezing of the 5 ml volumes was not homogeneous, due to the large section area between the surface and the core of the straw.hygienic (HAMMITT and MARTIN, 1989). For practical reasons, a larger frozen volume (i. e.

Effects of cryopreservation on semen quality and the expression of sperm membrane hexose transporters in the spermatozoa of Iberian pigs

“…In our study, the sperm motility percentages obtained are lower than the standard values for post-thawed semen in non-Iberian boars (45-50%; Bwanga et al 1990). However, no real data exist for this parameter in Iberian boars and differences in experimental design, package systems, breeds or individual male responses to Immunological study of cryopreserved sperm cryopreservation must also obviously be taken into account.…”

“…Several other authors have also observed an increase of 50-60% altered acrosomes after thawing (Bwanga et al 1990, Fiser & Fairfull 1990, Hofmo & Almlid 1991, Verheyen et al 1993.…”

“…The sensitivity of the boar sperm membranes to cooling seems to be strongly related to the characteristic lipid composition of these membranes (Bwanga 1991, Parks & Lynch 1992, Watson 1995. Focussing on this point, it is worth noting that Pettit & Buhr (1998) reported that lipid modifications also occur during freezing and thawing, indicating that different domains of the sperm head plasma membrane react differently to cryopreservation.…”

“…The characteristic lability of the boar spermatozoon during cooling (Mazur 1963, Pursel et al 1973, Watson et al 1981 and the specific lipid composition of its membrane (Holt & North 1984, Bwanga 1991, Maxwell & Johnson 1997, Johnson et al 2000, He et al 2001 affect its survival post-thaw that, even when proven protocols are used (Westendorf et al 1975, Bwanga 1991, Eriksson & Rodríguez-Martínez 2000, Johnson et al 2000, He et al 2001, Carvajal et al 2004, still remains sub-optimal. Many attempts have been made to reduce the alterations produced in sperm cells during this process (Breininger et al 2005, Peñ a et al 2005, Bathgate et al 2006, but the results are still far from optimal.…”

Reproduction in Pigs Using Frozen-Thawed Spermatozoa from Epididymis Stored at 4C.

“…Boar epididymal spermatozoa can be frozen and used for IVF [2]. Normally, before freezing, they are diluted with extenders at a temperature of between 15 C and 4 C, then gradually cooled to 4 C and cryopreserved, using the same procedure as for ejaculated boar spermatozoa (reviewed by Bwanga [14]). …”