Genetic insights into enteric methane emissions in indoor-fed growing cattle

Area of Science:

• Animal Science
• Genetics
• Environmental Science

Background:

• Growing interest in genetic selection for reduced enteric methane emissions in ruminants.
• Uncertainty exists regarding methane trait definitions that best capture exploitable genetic variation independent of existing breeding program traits.

Purpose of the Study:

• To explore genetic variability in methane-related traits in growing beef cattle.
• To quantify the proportion of genetic variance in daily methane production independent of performance traits (feed intake, growth, body size).

Main Methods:

• Methane and CO2 emissions measured using GreenFeed systems on 1,700 beef cattle.
• Performance traits (feed intake, liveweight, ADG, carcass weight) collected.
• Thirteen methane traits generated, including daily methane production and residual methane production (RMP) traits.
• Genetic parameters estimated using animal linear mixed models.

Main Results:

• Daily methane production is moderately heritable (0.42 ± 0.09) and genetically correlated with feed intake (0.51), ADG (0.39), and carcass weight (0.42).
• Genetic adjustment for performance traits reduced the genetic standard deviation of methane production by 25%, leaving 56% independent variance.
• RMP traits showed moderate heritability (0.38-0.46) and strong positive genetic correlations with daily methane production (>0.84).

Conclusions:

• Genetic selection can reduce methane emissions in growing beef cattle.
• A substantial portion of genetic variation for methane emissions overlaps with traits already under selection.
• Consideration of genetic correlations is vital for cost-benefit analysis in methane selection programs.