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Inferring Causalities of Environmental and Genetic Factors for Differential Somatic Cell Count and Mastitis Pathogens
Patricia Wagner1, Kerstin Brügemann1, Tong Yin1
1Institute of Animal Breeding and Genetics, Justus-Liebig-University of Gießen, Ludwigstr. 21b, 35390 Giessen, Germany.
Genes
|November 25, 2023
Summary
This study models how environmental and genetic factors impact cow udder health. It reveals housing systems indirectly affect intramammary infection through production, highlighting genotype-environment interactions.
Area of Science:
- Veterinary Medicine
- Animal Genetics
- Dairy Science
Background:
- Udder health is crucial for dairy cow welfare and productivity.
- Understanding the interplay between environmental and genetic factors influencing udder health is complex.
- Previous research has identified genetic markers for mastitis but lacked a comprehensive causal model.
Purpose of the Study:
- To develop and validate a structural equation model (SEM) to elucidate causal pathways between environmental and genetic factors affecting udder health in Holstein Friesian cows.
- To quantify the direct and indirect effects of housing systems on intramammary infection (IMI) and production.
- To identify specific genetic markers and their interactions with environmental factors influencing udder health.
Main Methods:
- Utilized data from 537 Holstein Friesian cows, including genotyping and milk sample analysis.
- Developed a structural equation model with latent variables: intramammary infection (IMI), production, time, and genetics.
- Incorporated manifest variables such as udder pathogens, somatic cell counts, milk composition, and significant SNP markers.
Main Results:
- Housing systems showed a small direct effect on IMI (-0.05) but a significant positive effect on production (0.37).
- Production significantly influenced IMI (0.17), establishing an indirect link between housing and udder health.
- Genotype-environment interactions were observed, with specific genetic markers (SNPs) relevant to particular housing systems.
- A key SNP in the *EVA1A* gene, involved in the MAPK1 signaling pathway, was identified as important for udder health genetics.
Conclusions:
- Structural equation modeling effectively infers indirect associations between housing systems and udder health via production.
- Genotype-environment interactions play a significant role in udder health, necessitating system-specific genetic evaluations.
- The *EVA1A* gene and MAPK1 signaling pathway are critical targets for improving udder health through genetic selection.
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