Disease & heat resistance

Are permanent environmental effects truly permanent? Estimating the genetic background of their temporal variability and genetic correlations with resilience traits in dairy cattle

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Abstract

Advancements in precision dairy farming and the widespread adoption of automatic milking systems have enabled the collection of extensive longitudinal data, offering new insights into the variability of permanent environmental (PE) effects across lactations. Traditionally modeled as constant, PE effects may vary over time, influencing genetic evaluations and selection decisions. To understand this variation, this study aimed to: 1) estimate PE effects across days in milk (DIM) using random regression models (RRM), treating lactations 1 to 3 as distinct traits; 2) evaluate the genetic component of the variation observed in the PE variance across DIM; and 3) assess the genetic correlation between PE variation and four resilience indicator traits, i.e., weighted frequency of perturbations (wfPert), accumulated milk losses (dPert), log-transformed variance (LnVar), and lag-1 autocorrelation (rAuto). We analyzed approximately 1.5 million daily milk yield (MY) records from 4,107 genotyped Holstein cows across the first three lactations using RRM with third-order Legendre orthogonal polynomials. The PE effects were estimated across DIM, revealing distinct trajectories and variability across lactations. Log-transformed standard deviations of PE effects were used as phenotypes to estimate heritability, which ranged from 0.01 to 0.14 (SE: 0.01 to 0.02), indicating a modest but non-negligible genetic component. Genetic correlations between PE variability and the four resilience indicator traits ranged from 0.45 (wfPert in first lactation) to 0.94 (dPert in third lactation) (SE: 0.03), suggesting important genetic overlap between PE variability and resilience. The modeling approach used in this study allowed for more nuanced insights into individual animal performance stability, with implications for selection strategies. Our findings challenge the assumption of constant PE effects and suggest that modeling their variability can improve selection decisions. This approach may help identify animals with greater adaptability to environmental fluctuations, contributing to more resilient and productive dairy herds.

Keywords: 2026

How to Cite:

Brito, L., Pacheco, H. & Rojas de Oliveira, H., (2026) “Are permanent environmental effects truly permanent? Estimating the genetic background of their temporal variability and genetic correlations with resilience traits in dairy cattle”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286853. doi: https://doi.org/10.31274/wcgalp.24145

Rights: 1