SHEEPREP

Advanced Studies on Improving Sheep Fertility by Using Artificial Means of Reproduction

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 Obiettivo del progetto (Objective)

'Artificial insemination (AI) in livestock has made it possible to optimize reproduction efficiency. AI is undoubtedly the management technique that has most contributed to the genetic improvement of livestock in modern animal production. By comparison to the other currently available preservation methods of semen, cryopreservation is an established industry used worldwide for performing AI, as it can preserve cells life undefinitely. The main disadvantage of semen cryopreservation is that freezing and thawing induce several forms of cellular lesions, which reduce dramatically the quality and subsequent fertilizing ability of the semen. Sperm motility, viability, membrane integrity and biochemical parameters are all routinely used tests to assess the quality of frozen-thawed semen. However, acceptable motility and viability of spermatozoa do not necessarily lead to acceptable conception rates. By this research project, we aim at increasing the conception rate in ewes following AI, by using frozen-thawed semen. In order to achieve this goal, we have the following objectives: to improve the freezing technologies, to evaluate the cytological and cryobiological indexes of the spermatozoa, to obtain accurate biochemical and electronomicroscopical profiles of the cryopreserved cells, and to test in vivo the efficiency of different preserving and AI technologies, on the cryobiological parameters and reproduction indexes.'

Introduzione (Teaser)

Professionals in the field of reproduction have improved sheep fertility through artificial insemination (AI), thanks to an EU-funded initiative.

Descrizione progetto (Article)

AI has contributed more than any other technique to the genetic improvement of livestock in modern animal production. The cryopreservation of semen at sub-zero temperatures means that cells can be preserved almost indefinitely. The main disadvantage to this technique, however, is that freezing and thawing can damage cells, significantly reducing the quality and subsequent fertility of the semen.

An EU-funded project titled 'Advanced studies on improving sheep fertility by using artificial means of reproduction' (SHEEPREP) aimed to increase the conception rate in ewes following AI, using frozen-thawed semen. This was achieved by improving freezing technology, evaluating spermatozoa, and testing the efficiency of different preserving and AI technologies.

The initiative also encouraged cooperation in international and cross-disciplinary research by bringing together specialists from Europe, North Africa and North America. These experts were drawn from the fields of genetics, reproduction, histology, biochemistry, biology and livestock management.

Project results showed that the addition of the amino acid cysteine to the dilution media used for ram semen improved the quality of frozen-thawed ram semen. A new diluting-preserving media based on soybean milk with the biochemical buffer Tris, (hydroxymethyl) aminomethane, also showed encouraging results regarding sperm cell motility.

Fertility rates were found to be higher when frozen sperm was diluted with Tris medium associated with the amino acid cysteine. The use of a helium-neon laser for irradiating frozen-thawed ram sperm cells was also developed and showed encouraging results concerning the improvement of semen quality.

Work conducted by SHEEPREP highlighted the use of AI programmes in flocks as the best way to ensure genetic improvement. Through the use of AI, any breeder can have access to the best genes from their flock as well as obtain more milk and meat throughout the year by controlling breeding. Furthermore, AI can help reduce the risk of transmitting reproductive diseases.