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.
Led 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).
Background on 12 steers
The 12 steers used in this contest were selected from 84 Brangus steers recently used for a research project that measured RFI. These calves were born and raised on a progressive beef cattle operation in central Texas. The rancher has done extensive genetic and progeny testing of his cattle over the years and does an excellent job of managing his cowherd and calves.
These steers were born in January and February 2013, underwent a VAC-30 preconditioning program, and were weaned in August 2013. In order for the rancher to get more data on the progeny from the herd (including RFI), these steers were transported to the Beef Cattle Systems Research Center at TAMU in College Station in late September 2013.
All 84 steers were individually weighed, dewormed and assigned to pens equipped with electronic feed bunks (GrowSafe System) to measure feed intake while fed a feedlot diet formulated to meet nutritional requirements to support gains of 3.2 lbs./day (NRC, 1996). During a 98-day trial, feed intake and serial body weights were measured in order to determine RFI for each of the steers.
Following the 98-day trial at TAMU, steers were shipped to a commercial feedyard, and they were fed a feedlot diet in a single pen for an additional 152 days prior to harvest at a commercial slaughter and processing plant. Carcass data were collected to determine USDA yield grade and quality grade, and carcass value determined using a carcass grid.
The carcass grid was constructed using July 1 USDA market news reports and can be found on the contest website. In addition, one strip loin steak was collected from each carcass to measure shear force following a 14-day postmortem aging period.
Net revenue (NR) for each steer was calculated as carcass income (hot carcass weight times grid-based carcass value) minus total expenses including purchasing the feeder calf, yardage (25¢/day), processing and transportation costs ($68/head), and feed and interest costs.
Feeder calf cost was based on initial body weight times average feeder steer price for October 2013 (USDA, AMS Market News Service) using a price slide at 100-lb. increments. Interest cost was calculated at 5% on total purchase price of feeder steer, plus 50% of total feed cost.
Since individual feed intake was not collected when steers were fed in the feedyard, DM feed required (DMR) by each steer was predicted using the Cattle Value Discovery System, which was based on individual average daily gain (ADG) and average body weight during the feedyard phase and carcass data collected at harvest. Each steer’s DMR was then adjusted according to its RFI, with the assumption that RFI rank measured during the individual feeding phase was maintained during the feedyard phase.
How does the contest work?
All contest entries are electronic, and readers can enter by filling out the online form at the contest website. Review the photos and videos and answer the questions on the contest ballot. Prizes will be awarded in three categories: 14-18 years of age (youth), 19 years and older (adult), and feedyard team. The prizes include:
- Youth: $1,000 Visa gift card
- Adult: $1,000 Visa gift card
- Feedyard team: $5,000 in Merial products
Entries must be received on or before midnight on Oct. 20, 2014, and only one entry is allowed per person. For any ties, a tiebreaker will be applied; if a tie persists, the tying forms will be randomly selected to determine a winner. See the official rules here.
The feeding performance and carcass results for these 12 steers will be unveiled in the November issue of BEEF magazine as well as online at the contest website. Also, photos and video of the finished steers and photos of the carcass 12th-rib cross-section (rib-eye) will be uploaded to the contest website in November.
No endorsement of products and services by Texas A&M AgriLife Extension and TAMU is implied.