Swine

Selection for decreasing androstenone in the French Landrace pig breed

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Abstract

Androstenone, which accumulates in fatty tissue, is one of major compounds responsible for boar taint. Due to its strong genetic determinism, selection could effectively reduce its levels and the associated defect risk without castration. This steroid is closely related to estradiol, and its measurement in blood samples offers a simple and cost-effective phenotyping method. While the genetic determinism of androstenone has been investigated in French Landrace maternal lines, its relationship with reproductive traits and the potential response to selection have not yet been studied. The objective of this study was to estimate the genetic parameters of boar taint compounds in relation to production and reproductive traits, and to assess the selection response through breeding scheme simulations. A total of 1,084 male French Landrace pigs, born in several farms, were raised post-weaning at the Le Rheu phenotyping station and slaughtered in a single slaughterhouse. Estradiol (from blood samples taken one day before slaughter) and androstenone (from backfat samples collected at slaughter) concentrations were measured for these animals. Contemporary pigs from the whole population were included in the dataset to estimate genetic correlations with production traits- feed conversion ratio (FCR), age at 100kg (AGE), loin depth (LD) and backfat thickness (BFT)-and with reproductive traits-number of born alive (NBA), piglet mortality (PM), number of small piglets (NSP) and mean piglets weight within the litter (MW). Genetic parameters were estimated using VCE6 software with an animal model, including weight at the start of the control period as a covariate, and batch effect and fattening pen as fixed effects. Breeding schemes were simulated using a stochastic method with the AlphaSimR package in R version 4.4.2. The selection index was composed of NBA (35%), FCR (28%), AGE (25%), PM (4%), MW (4%), BFT (3%), LD (1%), and NSP (1%). Two scenarios were tested: one without including estradiol in the selection index, and another in which estradiol accounted for 5% of the index variance, with a proportional decrease in the weight given to other traits. Genetic parameter estimations revealed high heritabilities for estradiol (0.73) and androstenone (0.78), which are strongly correlated (0.86). Estradiol and androstenone were positively correlated with FCR (0.47 and 0.24, respectively) and negatively correlated with PM (−0.25 and −0.28, respectively). Simulations showed a greater decrease in estradiol and androstenone levels when estradiol was included in the selection index than when it was not included (−0.20 vs. −0.07 and −0.13 vs. −0.03, respectively, related to phenotypic deviation). However, the selection response for other traits was similar in both scenarios, particularly for PM, despite its negative relationship with estradiol. In conclusion, although an unfavorable relationship exists between boar taint components and PM, the current selection strategy avoids an increase in mortality rate.

Keywords: 2026

How to Cite:

Taussat, S., Banville, M., Mercat, M., Ligonesche, B., Lenoir, G., Prunier, A. & Larzul, C., (2026) “Selection for decreasing androstenone in the French Landrace pig breed”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286308. doi: https://doi.org/10.31274/wcgalp.23917

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