Effect of sperm pre-selection by Equipure® and Percoll® on stallions' frozen semen quality

• Grant number: 11/14287-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2011
• End date: August 31, 2012
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Marco Antonio Alvarenga
• Grantee: Carlos Ramires Neto
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

In horses, due to the selection of reproductors not being based on the fertility of the animals, there are many stallions with a semen quality not recommended for use in artificial insemination or semen freezing. To improve the quality of semen, sperm selection techniques can be used. There are a variety of studies and protocols related to this subject in bovine and human reproduction, however equine literature is scarce. The most used product to separate motile sperm from the ejaculate is Percoll®, however, some authors have reported toxic effect on sperm and low sperm retrieval with its use. Recently, a new system called Equipure® was proposed, which is a colloid composed by silica particles. Some studies in humans and cattle compared the use of Percoll® and the new colloid to select the ejaculated sperm of these species, but there are no reports of this comparison when it comes to the semen of stallions. This work's purpose is to standardize and compare the use of these two techniques for selection of spermatozoa in the semen of stallions prior to freezing, and to monitor its effects on seminal quality and integrity after thawing. For the development of the project, the semen of 20 stallions will be frozen, in which ten will be a high quality sperm with high resistance to cryopreservation, and ten will be a low-quality sperm with low resistance to cryopreservation. The sperm selection will be made using Percoll® with continuous and discontinuous gradient, and Equipure® with continuous gradient. The integrity and kinects of sperm plasma membrane will be analyzed before and after freezing, and in an aliquot of each group the analysis of sperm morphology and sperm DNA fragmentation will also be made.