Genetic variation in novel calf traits using a farmer-centered, co-design approach to data collection

Area of Science:

• Animal Genetics and Breeding
• Dairy Science
• Veterinary Epidemiology

Background:

• Dairy farm productivity and animal welfare are significantly impacted by calf health.
• Genetic evaluations traditionally focus on cow health, with calf health being an emerging area.
• Improved record-keeping is essential for advancing research and genetic evaluations in calf health, particularly in Australia.

Purpose of the Study:

• To estimate variance components for novel calf health traits using a farmer-co-designed dataset.
• To assess the genetic basis of calf vitality, preweaning mortality (PWM), and scours in Australian Holstein calves.
• To explore genetic correlations between calf health traits and other production or health indicators.

Main Methods:

• Collected nearly 20,000 calf records from over 50 Australian farms (2020-2023).
• Utilized univariate linear models with a genomic relationship matrix to estimate variance components.
• Included fixed effects such as herd-year-season, sex, parity group, and calving ease.

Main Results:

• Preweaning mortality (PWM) prevalence was 2.0% and scours prevalence was 5.9% in Holstein calves.
• Heritability (h²) for calf health traits ranged from 1% to 11% in Holsteins.
• Calf vitality showed modest but favorable genetic correlations with stillbirth and PWM; few significant correlations with lactating cow traits were observed.

Conclusions:

• While heritability estimates for novel calf health traits are low, they provide a foundation for future genetic evaluations.
• The developed dataset and methods enable further research into improving calf health in Australian dairy herds.
• Genetic variance for calf health traits could not be reliably estimated for the Jersey breed due to insufficient data.