OPTIMIZANDO PROTOCOLOS PARA MEJORAR EL BIENESTAR ANIMAL MEDIANTE LA CONSERVACIÓN DE SEMEN EQUINO

Abstract

The transport of refrigerated semen and its use by artificial insemination (AI) is a routine practice in equine reproduction which avoids transporting animals, reduces risks, animal stress and transportation costs and increases the chances of using a breeder (Douglas-Hamilton 1987). In the last decades, AI with frozen semen in equines has acquired great importance. This biotechnology makes it possible to store valuable genetic material and use it even when stallions are no longer available, and the genetic material of a stallion can be distributed worldwide. Refrigerating diluted semen and storing it for a few hours while preserving semen parameters similar to those of fresh semen would allow the semen to be transferred to a laboratory for subsequent freezing. This would make it possible to collect semen in the field and transfer the ejaculate to a laboratory for freezing without the need to transport the stallions or to have a laboratory on site. The objective was to study sperm survival in equine semen after refrigeration at 4°C for 4 hours and post-thawing. Ten stallions were used. Two ejaculates from each animal were collected with an artificial vagina. After filtration, macroscopic characteristics were evaluated: Color, Appearance, Volume (ml) and microscopic characteristics: (AndroVision®, Minitüb GmbH, Tiefenbach, Germany) Progressive motility (PM); Percent live with Eosin - Nigrosin staining [% PV]; HOS test ([% rolled tails] post incubation in 50mOsm lactose solution). Intact acrosomes (AI, % intact acrosomes) Filtered semen was diluted to a concentration of 50 x106 per ml in a skim milk-glucose based diluent, stored at 4°C for 4 h and then frozen. In both stages, the semen was subjected to the microscopic contrast tests described above. The data obtained were analyzed by ANOVA. Significance was established as p<0.05. Similar values of MP, VM, HOS and AI were observed in fresh semen and after 4 hs of refrigeration. Likewise, the latter were compared with post-thaw values (57.6±4.8 vs 20.07±5.8; 66.5±2.8 vs 60.9 ± 3.8, 66.5±3.5 vs 36.09±5.1; 80.4±2.6 vs 60.3±3.6 respectively). Our results suggest that refrigerated semen could be transported and frozen after 4h of storage at 4°C, allowing collection in the field and cryopreservation in a properly equipped laboratory without the need to transport the equines. Future studies will allow to deepen the knowledge on refrigeration for short periods prior to freezing.