Between-cow variation in the components of feed efficiency.
A Guinguina1, T Yan2, P Lund3
1Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
Journal of Dairy Science
|July 21, 2020
Summary
Feed efficiency (FE) in dairy cows varies significantly between individuals, with milk energy output showing the most variation. Selecting cows for better energy utilization can effectively reduce enteric methane emissions.
Area of Science:
- Animal Science
- Nutritional Physiology
- Dairy Cattle Research
Background:
- Feed efficiency (FE) is crucial for sustainable dairy production.
- Understanding between-cow variation in FE components is essential for genetic improvement.
- Existing research often lacks comprehensive meta-analyses of individual-cow data.
Purpose of the Study:
- To investigate variations in feed efficiency components among individual dairy cows.
- To explore the associations between different feed efficiency measurements.
- To identify key components for improving feed efficiency and reducing environmental impact.
Main Methods:
- Meta-analysis of individual-cow data from 31 chamber studies (841 observations).
- Analysis of diets based on various forages and concentrates.
- Statistical analysis using mixed models to estimate variance components and repeatability.
Main Results:
- Gross energy intake and milk energy output showed the highest between-cow variation and repeatability.
- Digestibility, metabolizability, methane yield, urinary energy output, and heat production had low variation and repeatability.
- Residual energy-corrected milk (RECM) exhibited greater variation than residual feed intake (RFI), suggesting higher genetic gain potential.
- High energy digestibility was associated with increased methane yield, heat production, and metabolizability, but not energy intake.
Conclusions:
- Multiple mechanisms contribute to feed efficiency differences in dairy cows.
- Reducing methane emissions might inadvertently decrease energy digestibility.
- Selecting dairy cows with enhanced energy utilization efficiency is a viable strategy to lower enteric methane emissions.
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