Sustainability & efficiency

Heritability and genetic correlation of methane production measured using GreenFeed and portable accumulation chambers in dairy heifers

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Abstract

Enteric methane (CH₄) from ruminants is a major agricultural greenhouse gas. Genetic selection offers a permanent and cumulative mitigation strategy, but thousands of accurately phenotyped animals are needed for robust evaluations. Current CH4 measurement techniques differ in ease of use, precision, throughput and cost. It is important to understand the genetic relationships between CH₄ measured using different methods so that data from multiple sources can be integrated for genetic evaluations. Portable accumulation chambers (PAC) offer a rapid, lower-cost, higher-throughput alternative. PAC have been widely used for phenotyping sheep in New Zealand. Moderate to high genetic correlations have been reported between PAC and respiration chambers in sheep, supporting their potential for large-scale use. However, validation in cattle is required. The objectives of this study were to estimate the phenotypic and genetic correlations between CH₄ emissions measured using GF and PAC units, and to assess the suitability of PAC measurements for ranking animals in genetic evaluations. Methane production, dry matter intake (DMI), and liveweight records were obtained for 392 heifers , daughters of high- and low-methane sires identified using breeding values for CH₄ adjusted for DMI. Heifers, aged six to fifteen months, were measured across four rounds, each round spanning 39 days. Methane production recorded using PAC were conducted in weeks four and six of each round, except round one (week six only). Measurements were collected using four chambers, where heifers were removed from feed one hour pre-measurement and remained in the chamber for 45 minutes. Weekly average GF CH4 from corresponding weeks were paired with each PAC measurement (converted from ppm to g CH4 day-1). Separate linear mixed models were fitted for each method to estimate variance components and phenotypic correlations. A bivariate animal model was fitted in ASReml-R to estimate additive genetic (co)variances between GF and PAC traits with trait-specific permanent-environment and residual variances. Fixed effects were fitted separately for each trait: for GF CH₄, contemporary group used in linear mixed models, age (weeks), scaled proportion of Friesian and Jersey, and heterosis terms; and for PAC CH₄, contemporary group by date × lot, age, chamber, scaled proportions of Friesian and Jersey, and heterosis terms.Adjusted GF and PAC animal means were moderately correlated (r = 0.66), indicating a similar phenotypic ranking. The genetic correlation between GF and PAC CH₄ was 0.69 ± 0.18, and the Pearson correlation between animal genetic solutions was 0.81 ± 0.02, demonstrating similar genetic ranking across both methods. These correlations indicate that the two measurement methods ranked emissions and estimated breeding values similarly, which supports the application of PAC chambers for large scale CH4 phenotyping and for national evaluation for reduced CH4 emissions.

Keywords: 2026

How to Cite:

Bilton, T., Douie, J., Lopez-Villalobos, N., McNaughton, L., Rowe, S., Spaans, O., Spelman, R. & Tiplady, K., (2026) “Heritability and genetic correlation of methane production measured using GreenFeed and portable accumulation chambers in dairy heifers”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285229. doi: https://doi.org/10.31274/wcgalp.23640

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