Sustainability & efficiency

Residual heat production: a novel trait for dairy cow efficiency?

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Abstract

Feed efficiency is critical in dairy farming, as it directly impacts both production costs and environmental sustainability. Residual feed intake (RFI) is a widely used index to measure feed efficiency; however, it does not fully reflect metabolic efficiency or energy partitioning. In addition, phenotyping RFI is expensive, labor-intensive, and often limited to research farms. As an alternative, we propose the use of residual heat production (RHP), defined as the difference between observed and expected heat production (HP), which could be used as a measure of energy efficiency and measured in research and commercial farms. The objective of this study was to calculate the heritability and repeatability of RHP and estimate the genetic correlation between RHP and RFI. Data consisted of 9,106 dry matter intake (DMI) records from 7,009 mid-lactation Holstein cows collected between 2007 and 2025 in 7 research farms, and 1,786 gas production (CH4 and CO2 g/d) and consumption (O2, g/d) records from 1,571 mid-lactation Holstein cows collected between 2023 and 2025 in 6 research farms and 3 commercial farms. Gas emissions were measured using the GreenFeed system (C-Lock Inc., Rapid City, SD). Both DMI and gas emission records were collected for 6 to 12 weeks per cow per lactation. All cows also had milk energy and body weight records. We calculated HP (kJ/d) as HP = 16.18 * O2 (L) + 5.02 * CO2 (L) - 2.17 * CH4 (L). Both RFI and RHP were estimated as the difference between the observed and the predicted DMI or HP based on a linear regression including milk energy, metabolic body weight, change in body weight, days in milk, and cohort. Estimates of heritability, repeatability, and genetic correlations between RFI and RHP were obtained using bivariate repeatability animal models. These two efficiency traits are heritable, with heritability estimates of RFI = 0.26 ± 0.02 and RHP = 0.30 ± 0.07. In addition, these two efficiency traits are repeatable across lactations, with a repeatability of 0.39 ± 0.02 for RFI and 0.50 ± 0.05 for RHP. The phenotypic and genetic correlations between RFI and RHP were moderate (rp: 0.40 and rg: 0.55 ± 0.20), indicating that these two traits evaluate efficiency differently and thus, do not measure the same phenotype. Notably, as RHP does not require measuring daily intakes, it would allow the inclusion of phenotypes from animals in non-research settings in the U.S. genetic evaluation. Overall, RHP is a promising trait to evaluate efficiency in dairy cattle.

Keywords: 2026

How to Cite:

Baldwin, R., Carriquiry, M., French, E., Kalscheur, K., Koltes, J., Marin, F., Martinez-Boggio, G., Parker Gaddis, K., Peà±agaricano, F., Santos, J., Tempelman, R., VandeHaar, M., Weigel, K. & White, H., (2026) “Residual heat production: a novel trait for dairy cow efficiency?”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2284780. doi: https://doi.org/10.31274/wcgalp.23614

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