Cryopreservation and fertility of ejaculated and epididymal stallion sperm

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Freezing of stallion epididymal sperm

Inseminations with frozen-thawed epididymal sperm have resulted in low-pregnancy rates of mares. If fertility of epididymal sperm could be improved, it would help to preserve genetic material from stallions that have suffered severe injuries, been castrated or have died. The aim of the present study was to investigate the effect of different extenders and pre-freezing addition of capacitation media on freezability of epididymal sperm and on storage at 5 degrees C for 24 h. In experiment 1, epididymal sperm samples were diluted and subsequently frozen with three different extenders: Botu-Crio((R)), EDTA-Lactose and INRA-82. Motility analysis using computer assisted sperm analyzer (CASA) demonstrated better motility for sperm in Botu-Crio((R)) than in the other extenders; EDTA-Lactose yielded better motility than INRA-82 on most evaluated parameters. There was no difference in membrane integrity among the studied extenders. From 18 inseminated mares, 12 (66%) were pregnant 15 days after AI with frozen-thawed epididymal sperm showing that Botu-Crio((R)) was able to maintain the fertility potential. In experiment 2, the effect of incubation of epididymal sperm before freezing in three capacitation media (Fert Talp, Sperm Talp, Talp + Progesterone), seminal plasma, or control was tested. Based on post-thaw motility evaluation by CASA, samples incubated in Sperm Talp showed better motility values. There were no differences in plasma or acrosomal membranes or in mitochondrial potential among groups. We concluded that Botu-Crio((R)) was better than the other extenders in the ability to preserve epididymal sperm and that pre-freeze addition of Sperm Talp was also beneficial. (c) 2008 Published by Elsevier B.V.

Methods of Concentrating Stallion Semen

Removal of excess seminal plasma is sometimes necessary to increase the quality and the longevity of cooled equine semen; moreover, this procedure is an indispensable step aiming to concentrate the sperm cells before freezing equine semen. Typically, the removal of seminal plasma is achieved by centrifugation; however, studies have shown that the force and duration of centrifugation can damage sperm cells and reduce the sperm recovery rate. Recently, new methodologies, such as cushion and filtration, have been described that aim to decrease the mechanical damage of centrifugation to sperm cells. This study aims to compare different methods for concentrating stallion semen.

Advances in stallion's epididymal sperm technology

Freezing epididymal sperm is a method to preserve germplasm from animals with not only high genetic potential but also endangered species. In the equine some owners have chosen this possibility in cases of either severe illness or death of stallions. However, the lack of knowledge and poor published results of such technique hampers its propagation. New procedures have allowed some improvement on fertility rates of frozen sperm from the epididymis of stallions. The aim of this study is to report the advances on processing and cryopreservation of samples from the stallion's epididymal semen.