Dairy cattle

Associations Between Genomic Merit for Enteric Methane Emissions and Milk Quality and Cheese-Making Efficiency in Holstein cows

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Abstract

Greenhouse gas emissions from livestock farming, particularly enteric methane (CH₄) produced during ruminal fermentation, poses a significant environmental challenge. The overall objective of the CowMeTec project (project no.5953218) is to develop an integrated digital platform to monitor enteric CH₄ emissions per kilogram of potentially producible Parmigiano Reggiano cheese. This tool will support dairy farmers and technicians in making informed decisions within the Parmigiano Reggiano area. As part of CowMeTec, a pilot study was conducted in Emilia-Romagna (Italy) to investigate the phenotypic and genetic relationships between methane emissions and milk technological properties and cheese-making efficiency. Data were collected from 155 primiparous Holstein cows from two commercial farms, including nasal swabs (or Tissue Sampling Unit, TSU), milk samples, and feed samples. Genomic characterization involved DNA extraction and genotyping with a 70K SNP chip, followed by imputation and prediction of of genomic breeding values (GEBV) for Methane Production (MP) using Lactanet's routine single-step genomic evaluation framework. Milk phenotyping included gross composition, mid-infrared spectrum, fat globule size, total and differential somatic cell count, and mineral profile. For each cow, individual cheese-making trials were conducted following the standardized 9-MilCA protocol. Coagulation and cheese-making traits showed significant heritability, with h² estimates ranging from 0.17 to 0.28 for coagulation and from 0.18 to 0.31 for cheese-making traits. The point estimates for the mean and the standard deviation were obtained by computing the average of their respective bootstrap replicates. The 95% confidence intervals for each statistic were derived using the percentile method, in which the 2.5th and 97.5th percentiles of the bootstrap distribution serve as the lower and upper bounds, respectively. Coagulation traits showed a RCT of 22.32 ±4.20 min and a30 of 24.45 ± 3.04 mm. Cheese-making performance averaged 15.92 ±2.28% for %CYCURD, comprising 6.77 ±1.17% total solids and 9.14 ±1.59% water. %REC for protein, fat and total solids averaged 75.96 ±3.89%, 84.25 ± 8.41%, and 50.98 ± 5.03%, respectively. The parametric bootstrap test indicated that the genetic category for MP significantly affected, among the others, casein content, casein index, and curd yield. Cows in the low-emission category showed higher casein (2.98 ± 0.06%), a higher casein index (80.61 ± 0.22%), and a higher %CYCURD (16.73 ± 0.36%) compared with the other categories. Planned contrasts showed that High genetic category was higher than the average of Medium and Low categories by 0.11 ±0.06 for casein, 0.51 ±0.39 for curd yield, and0.25 ± 0.16 for the casein index. Overall, these findings point to a potential link between methane emission potential and milk protein partitioning with effects on technological performance.

Keywords: 2026

How to Cite:

Tedeschi, I., Stocco, G., Cipolat-Gotet, C., Dorigo, M., Finocchiaro, R., Biffani, S., Graziani, S., Tiezzi, F., Malchiodi, F., Fleming, A. & Miglior, F., (2026) “Associations Between Genomic Merit for Enteric Methane Emissions and Milk Quality and Cheese-Making Efficiency in Holstein cows”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2295334. doi: https://doi.org/10.31274/wcgalp.24336

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