Research in recent years in Australia, Canada and the U.S. indicates that net feed efficiency (NFE) or residual feed intake (RFI) is a new selection tool that may be useful for improving feed efficiency in beef cattle.
RFI is defined as actual feed intake minus expected feed intake for maintenance and growth. Therefore, an animal with a negative RFI would be more efficient than one with a positive RFI.
Australian work has shown that it is a moderately heritable trait (0.40), which suggests that selection for low RFI should be effective in improving feed efficiency.
Following is a brief summary of research on selection for low RFI:
Feed intake is reduced with no change in ADG or mature cow size.
Feed conversion ratio is improved.
Maintenance energy costs are reduced.
Fat thickness may be slightly reduced.
No change in marbling or ribeye area.
There is a correlated decrease in feed intake by replacement females and mature cows.
Olds College, Olds, Alberta, Canada, recently reported the first-year results of a three-year study to identify feed-efficient yearling breeding bulls. Three different groups of bulls (total of 110) were tested for RFI. The feed cost savings between the most- and least-efficient bulls in each group ranged from $38 to $64 over the 112-day feeding period. Dry matter intake differences between the most and least efficient bulls in each group ranged from 789 to 1,325 lbs.
Ongoing research on RFI is currently being conducted at the LaCombe and Lethbridge Research Centres and the University of Alberta.