A calf’s weight at various time in its life (birth, weaning, yearling, etc.), as well as carcass grade, are common selection tools used by beef producers. Meanwhile, feed efficiency historically has been a smaller consideration in progeny testing and cattle selection.

This is beginning to change thanks to new technologies, such as the GrowSafe SystemTM, that allow the measurement of individual animals’ feed intake and feeding behavior. In addition, there’s a relatively new concept called residual feed intake (RFI) that takes feed efficiency to a whole new level. 

This contest, a collaborative effort between BEEF magazine and Texas A&M University and sponsored by Merial, is designed to help cattle producers better understand the relationship between cattle efficiency and profitability. An important facet of the exercise will deal with the role of RFI.

Dan HaleLed by Dan Hale, TAMU professor and Extension meat specialist, and Gordon Carstens, TAMU professor of animal nutrition, the contest presents six steers with a high RFI (inefficient) and six steers with a low RFI (efficient) for readers’ evaluation. Photos and videos of these 12 steers are available for viewing on the BEEF website, which readers can use, along with the animals’ individual data, to make their choices.

In the November issue of BEEF, we’ll present the actual results and discuss the lessons. Then, in the December issue, we’ll announce the prize winners in three categories. Up for grabs is more than $7,000 in prizes for the winners in three contest categories.

The aim of this 12-steer exercise is to demonstrate the importance of feed efficiency on the profitability of a cattle enterprise, as well as the role of other economically relevant traits such as performance and carcass quality on profitability. In addition, readers will learn about the importance of obtaining data on your cattle to help you make genetic and management changes in your herd and improve your bottom line.

Background on RFI

Feed efficiency has typically been measured in beef cattle using feed-to-gain ratio (F:G). This is a gross measure of efficiency and doesn’t attempt to differentiate between the feed needed to support maintenance and growth-energy requirements. While studies have demonstrated that F:G ratio is moderately heritable in cattle, F:G ratio is known to be strongly correlated in an inverse manner with growth rate — cattle that grow faster have a lower F:G ratio. Consequently, F:G ratio has limited utility in selection programs, as favorable selection for F:G will lead to increases in cow mature size, and consequently, increases in the cost of feed needed to maintain the cowherd.

RFI is an alternative feed efficiency trait that quantifies animal variation in feed intake beyond that needed to support maintenance and growth-energy requirements. RFI is calculated as the difference between an animal’s actual dry matter (DM) intake and its expected DM intake, based on its body weight and level of production. Efficient cattle are those that eat less feed than expected based on their body weight and performance (e.g., growth rate); efficient animals will have a negative RFI.

Meanwhile, inefficient cattle are those that eat more feed than expected based on their body weight and performance; inefficient cattle will have a positive RFI. Therefore, the steer with a lower or more negative RFI number will be more efficient. Unlike ratio-based efficiency traits (F:G ratio) that are highly influenced by growth and maturity patterns, RFI is minimally related to the animal’s body size or level of production. Research has shown that RFI is moderately heritable in beef cattle.

To further illustrate the RFI concept, let’s compare Steer A and Steer B, which had similar daily gains (3.38 lbs. vs. 3.30 lbs./day, respectively) and similar final body weights (906 lbs. vs. 890 lbs., respectively) during the individual-feeding trial.

Because these two steers had similar gains and body weights during the trial, their expected DM intakes were very similar (22.3 lbs. vs. 22.0 lbs./day, respectively). However, Steer A consumed less DM feed during the trial than Steer B (20.8 lbs. vs. 24.3 lbs./day, respectively). Since RFI is calculated as actual minus expected DM intake, Steer A had a negative RFI (20.8 - 22.3 = -1.5 lbs./day), whereas, Steer B had a positive RFI (24.3 - 22.0 = +2.3 lbs./day).

Steer A consumed 1.5 lbs./day less feed than expected and had a lower F:G of 6.2, while Steer B consumed 2.3 lbs./day more feed than expected and had a higher F:G of 7.4. Considering the entire feeding period, Steer A generated $78 more profit than Steer B ($312 vs. $234, respectively).