GxE

Genetic connectedness and genotype-by-environment interaction across countries in a maternal pig line

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Abstract

To perform efficient selection among animals raised in different management units, we must be able to compare estimated breeding values (EBV) across farms, regions or countries. Although BLUP enables fair comparisons of EBV, the accuracy of these comparisons depends on the level of genetic connectedness between management units: the lower the connectedness, the lower the accuracy of EBV comparisons. Moreover, when comparing EBV from different management units, genotype-by-environment (Gà—E) interactions can be a potential source of inefficiency. Therefore, the aim of this study was to investigate the extent of genetic connectedness and Gà—E interactions between countries for five traits of economic interest: age at 100 kilograms (AGE), number of functional teats (NFT), birth weight (BW), backfat thickness at 100 kilograms (BFT) and number of piglets born alive (NBA) for a maternal pig line. The population is distributed across elite farms in France and Asia. Phenotypic records were collected from animals born between 2010 and 2024 in seven farms in France, between 2016 and 2024 in one farm in China, and between 2023 and 2024 in one farm in Thailand. The dataset comprised 149,531 records from France, 92,385 from China and 15,326 from Thailand. All farms follow the same genetic selection program with the same trait definitions and similar management practices. Semen is periodically shipped from France to Asia, to maintain genetic connectedness. Genetic connectedness was assessed using the coefficient of determination (CD), which is the reliability of EBV contrasts e.g. among countries, and the Wright's fixation index (Fst). Multi-trait animal models were fitted to model Gà—E interactions across countries, treating country-specific phenotypes as correlated traits. Average CD values (0.61-0.86), showed that the three countries were well connected across all traits and periods. France and China had higher CD values (0.80 on average) than France and Thailand (0.70 on average) between 2023 and 2024. These results were in line with Fst estimates (0.015 between France and China, 0.006 between France and Thailand, and 0.020 between China and Thailand), indicating that the populations in the three countries are genetically close. Genetic correlations among the countries ranged from 0.70-0.79 for AGE, 0.95-0.98 for NFT, 0.53-0.83 for BW, 0.81-0.97 for NBA, and 0.77 for BFT. Overall, there was no evidence of biologically relevant Gà—E interactions, except for BW between France-China (0.67), and China-Thailand (0.53). These results show that accurate and fair across-country genetic evaluations and comparison of EBVs is possible. Therefore, a single breeding program across countries is appropriate and effective.

Keywords: 2026

How to Cite:

Garcia-Baccino, C., Tusingwiire, T., Legarra, A., Aguilar, I., Ligonesche, B., Larzul, C. & Vitezica, Z., (2026) “Genetic connectedness and genotype-by-environment interaction across countries in a maternal pig line”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286511. doi: https://doi.org/10.31274/wcgalp.24034

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