Disease & heat resistance

Sequence-based GWAS of heat tolerance traits in Holstein and Montbeliard cattle

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Abstract

Global warming will affect cattle production systems, decreasing overall performance and welfare. In such a context, it is thus relevant to identify genomic regions involved in heat tolerance for production and functional traits. By combining the French bovine genetic database (focusing on French Holstein and Montbéliarde dairy cattle) with weather conditions (Safran database, MeteoFrance), we estimated breeding values (BV) of animals along a temperature-humidity index (THI) gradient with reaction-norm models. These models were applied to three primiparous traits: test-day milk yield and somatic cell score, and conception rate at first insemination. Several traits were then defined: levels at average THI (50) and high THI (70), and slopes along the THI gradient. The genetic slopes were estimated in two different ways: the first derivative of BV at THI 70 and the difference between BV at THI 70 and THI 50. Phenotypes for GWAS were deregressed proofs derived from levels and slopes. The 50K SNPs genotypes from 4564 Holstein and 1737 Montbéliarde bulls were imputed to whole genome sequence using the run9 of the 1000 bull genomes project, resulting in ~13 million SNPs (R² Minimac ≥ 0.2 and MAF ≥ 0.02) to perform a within-breed GWAS of levels and slopes' deregressed proofs. A few genomic regions were significantly associated with the heat tolerance traits, however these regions differed between breeds and traits. Beyond revealing novel regions associated to heat tolerance, our study also identified some QTL targeting genes already reported in heat tolerance studies, emphasizing their relevance (i.e. variants in VSP13B, ASL, KIRREL3 or RABGEF1 genes). Finally, QTL associated with slopes, i.e. with heat tolerance, were not associated with levels, suggesting that selection for QTL favorable to heat tolerance and without antagonistic effects on traits currently under selection is possible. This study received funding from the European Union's Horizon 2020 research and innovation program under grant number 101000226 (Rumigen) and from APIS-GENE (CAICalor). The authors thank MeteoFrance for the Safran database.

Keywords: 2026

How to Cite:

Vinet, A., Vallée, R., Mattalia, S., Barbat, A., Bertrand, C., Hozé, C., Sanchez, M., Boussaha, M., Cuyabano, B. & Boichard, D., (2026) “Sequence-based GWAS of heat tolerance traits in Holstein and Montbeliard cattle”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285900. doi: https://doi.org/10.31274/wcgalp.23817

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