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Towards improved boar fertility by genetic characterization and detection of traits important in sperm production and quality

Woman with pig (photo: Norsvin/Jens Haugen)

(Photo: Norsvin/Jens Haugen)

Increased variations of sow reproduction is observed between different AI boars and the sperm, especially from Duroc boars, have lower quantity and more variation in quality than demanded from efficient semen boars. Moreover, recent studies show unfavorable correlations between sperm quality and important production traits, and between major sex hormones and boar taint. Selection of boars has traditionally focused on economically important traits and the sow reproduction, and so far no available parameters are sufficiently describing the boars reproductive capability.

In this project we want to find the traits describing the boar fertility as accurately as possible, and establish the most efficient and cost effective way to measure those traits. Additionally, we want to detect associations to other traits in the breeding goal, identify the underlying genes, genetic networks and biochemical pathways of boar fertility, and ultimately use the results and information in practical breeding to improve boar fertility.

A thorough boar breeding strategy will benefit Norwegian pig industry and make Norsvin pigs more attractive internationally. If we are able to genetically increase the boar fertility and decrease the level of boar taint, without reducing other favorable traits in the breeding goal this would be a huge step in the international pig breeding society.

The use of new and highly improved molecular genetics tools will make the data much more applicable and can facilitate effective pre-selection of candidates entering the boar test. The project will contribute considerably to the development of scientific knowledge on semen quality and genetics in Norsvin, Nortura (owner of the Duroc breed) and our project partners. Economic gain due to increased litter size, increased farrowing rate and reduced number of sperms per dose is estimated to be as much as 140-200 mill NOK per decade.

Aims of the project

The main goal is to establish key boar fertility parametres, study their underlying genetics, and to use this knowledge in practical breeding to produce boars with good fertility traits without negatively affecting other production or quality traits.

Subsidiary goals

  • Characterize the parameters describing boar fertility as comprehensively as possible using new objective high-technology methods (Flow cytometry, Nucleocounter, CASA) together with simple and quick on-site recording for routine use.
  • Estimate genetic parameters of the defined traits and study the genetic relationship between those traits and production- and quality traits, including the most important boar taint compounds.
  • Identify genetic factors affecting boar fertility and other related traits using high density marker panel and the genome wide association approach.
  • Identify differentially expressed genes in boars with good and bad sperm quality by using transcriptome sequencing, which provides the possibilities to analyse expression pattern for thousands of genes at the same time.
  • Confirm the physiological importance of the detected genes at the certaint time and conditions, applying the proteomic technologies for selected proteins.
  • Development of an efficient breeding strategy to produce boars with highly improved fertility traits based on the previous findings.