Periódicos Brasileiros em Medicina Veterinária e Zootecnia

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Cryopreservation of Equine Semen Loaded in Cryovials

Lorenzoni, Sabrina Leães GomezArruda, Natalia SchmidtRodrigues, José Luiz

Background: Over the past twenty years the assisted reproduction techniques reached a rapid advance in domestic species of economic interest. By the time the male gamete has provided to be the most successful tool used to improve animal breeding programs. Freezing and stock of semen is a safe procedure to preserve reproductive potential of animals with superior genetic heritage. In the horse industry, unlike observed in ruminants, the development of sperm cryopreservation techniques is very slow but despite the technical barriers the artificial insemination with frozen semen is growing. Materials, Methods & Results: This experiment was divided in three steps. The first one compared the use of different diluents and freezing techniques. The other two stages were the use of cryogenic tubes for storing semen and the determination of mare pregnancy rates that were artificially inseminated with frozen semen packaged in cryogenic tubes. Six stallions were submitted to semen collection and twelve mares were artificially inseminated at first estrus of the breeding season. The samples were diluted in INRA82 or Nagase, containing 5% glycerol, with a concentration of 200 x 10 6 sperm/mL. A fraction of the diluted semen was stored in straws (0.5 mL), some of those straws were immediately frozen. The remaining straws were cooled from room temperature (± 24°C) to 5°C before freezing. The samples were thawed in a water bath at 37°C during 30 s. The same protocol with cooling prior to freezing was performed with samples filled into cryogenic tubes, and these samples were thawed in a water bath at 50°C during 100 s. The in vivo efficiency of cryopreserved semen was determined through artificial insemination (AI). The pregnancy diagnosis was performed after 20 days by ultrasound examination. After analyzing the data it was found that there was no significant difference in sperm motility and vigor among the tested diluents. [...](AU)

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