Genetic parameters for feed efficiency in Romane rams and responses to single-generation selection

Area of Science:

• Animal Science
• Genetics
• Agricultural Economics

Background:

• Feeding costs are a major expense in animal production.
• Improving feed efficiency is crucial for sustainable livestock farming.
• Residual Feed Intake (RFI) is a key trait for measuring feed efficiency.

Purpose of the Study:

• Estimate genetic parameters for feed intake, feed efficiency, growth, and body composition in Romane meat sheep.
• Evaluate selection responses to divergent selection on RFI.
• Determine the heritability and genetic correlations of RFI with other production traits.

Main Methods:

• A total of 951 male lambs were tested over 8 weeks.
• Feed intake was continuously monitored using automatic feeders.
• Growth and body composition (backfat thickness, muscle depth) were measured via weighing and ultrasound.

Main Results:

• Heritability of RFI was estimated at 0.45 ± 0.08, higher than FCR (0.30 ± 0.08).
• No significant genetic correlations between RFI and growth traits were found.
• Divergent selection on RFI reduced daily feed intake by 3% with no impact on growth.

Conclusions:

• Residual Feed Intake (RFI) is a heritable trait in meat sheep, largely independent of growth and body composition.
• Selection for lower RFI offers substantial potential for reducing feeding costs in sheep breeding programs.
• Targeting RFI in breeding schemes can lead to more economically efficient meat sheep production.