Reproduction

Genetic parameters for semen traits in five commercial pig lines

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Abstract

Semen quality and quantity traits are key indicators of male fertility and play a crucial role in the efficiency of artificial insemination programs in livestock breeding. Understanding the genetic architecture and phenotypic variation of these traits is essential for improving male reproductive performance and realizing potential genetic progress. This study estimated genetic parameters for 5 semen traits across five pig lines. The dataset comprised 413,871 ejaculates collected for artificial insemination from 7,417 boars between January 2020 and June 2025. Table 1 shows descriptive statistics and results from the analysis. Each boar had at least three ejaculates recorded, with an average of 56 ejaculates per boar. The 5 semen traits analyzed were; NR_CEL: total number of sperm cells per ejaculate, MOT_0: motile sperm in fresh semen (%), PROX_DROP: proximal droplets (%), DIST_DROP: distal droplets (%) and DMR: distal midpiece reflex (%). Data were collected from eight different AI stations located in Canada, the Netherlands and Norway. The semen traits were measured using Computer-Assisted Sperm Analysis (CASA) or measured in microscope analysis and maximum 20 percent of the obsevations for a trait was from microscope. Variance component analyses were performed using a single-trait linear animal model with repeated records in ASReml-R. Fixed effects included line code, herd X year of birth, laboratory technician, collector, month of collection, and regression effects for age at collection, age squared, and days since the previous collection. Random effects included permanent environmental effect, additive genetic effect, and residual. The pedigree-based A matrix was constructed from 5 generations and included 25,314 animals. Estimated heritabilities across the five lines were; NR_CEL: 0.15 ± 0.01, MOT_0: 0.13 ± 0.02, PROX_DROP: 0.24 ± 0.03, DIST_DROP: 0.23 ± 0.02 and DMR: 0.28 ± 0.04. The 5 semen traits exhibited moderate heritabilities, indicating potential for genetic selection to improve semen quality and quantity in boar breeding programs. Further work will focus on estimating genetic correlations among semen traits and calculating genomic breeding values using a multivariate model. This approach will enable monitoring of genetic trends and selection of boars for semen traits based on breeding values. Quantifying genetic variance for these traits allows for economic analysis of their potential inclusion in breeding goals.

Keywords: 2026

How to Cite:

Andersen-Ranberg, I., Godinho, R., Larsgard, A., Iversen, M., Heringstad, B. & Grindflek, E., (2026) “Genetic parameters for semen traits in five commercial pig lines”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285426. doi: https://doi.org/10.31274/wcgalp.23698

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