Phenotypic relationship and repeatability of methane emissions and performance traits in beef cattle using a...

Area of Science:

• Animal Science
• Environmental Science
• Agricultural Science

Background:

• Rumen methanogenesis in cattle is a major source of anthropogenic methane (CH4) emissions, representing a significant loss of gross energy intake.
• Understanding the relationship between greenhouse gas emissions and production traits is crucial for sustainable beef production.

Purpose of the Study:

• To analyze greenhouse gas traits in a commercial feedlot setting.
• To investigate the relationships between methane (CH4) and carbon dioxide (CO2) emissions and production traits in beef cattle.

Main Methods:

• Utilized data from 1,099 beef production animals (steers, heifers, bulls) including GreenFeed Emission Monitoring (GEM) system data for CH4 and CO2, feed intake, live weight, ultrasound, and carcass data.
• Assessed phenotypic relationships between GEM measurements and production traits, daily emission patterns, and measurement repeatability.
• Analyzed methane concentrations based on visit number, duration, and time of day.

Main Results:

• Mean CH4 emissions varied by sex: steers (256.1 g/day), heifers (234.7 g/day), and young bulls (156.9 g/day).
• Heavier animals exhibited higher CH4 (correlation = 0.30) and CO2 (correlation = 0.61) production; higher dry matter intake correlated with higher CH4 output (correlation = 0.31).
• A 10-day GEM measurement average was needed for steers and heifers to achieve 0.60 repeatability, while CO2 repeatability exceeded 0.6 with >2-day averages.

Conclusions:

• Reducing CH4 emissions may adversely affect cattle growth and body composition.
• Methane ratio traits are not ideal for breeding due to unpredictable responses.
• Residual CH4 (adjusted for dry matter intake and liveweight) is a recommended alternative trait for breeding goals focused on emission reduction.