Now is the Time to Get Serious About Cow Efficiency

by Associate Professor and Extension Animal Scientist, Auburn University Lisa A. Kriese-Anderson, PhD.

It has been over 30 years since the first Brangus expected progeny differences (EPD) values were published for Brangus breeders to utilize in selection decisions. Collecting actual weights and values for production and carcass traits used in EPD predictions are relatively easy. Much has been accomplished in moving production and carcass traits to more desired values and overall improvement of the Brangus breed. Newer DNA techniques, combined with phenotypic data, have made genomically-enhanced EPD predictions more accurate and reduced the risks of using non-parent animals.

The overall goal of a beef cattle producer should be to improve profitability. Because providing feed to animals is a major cost to producers, improving the efficiency of feed utilization would be of significant economic benefit. Efficient feeding programs are designed to provide cattle with the essential nutrients for maintenance and growth with minimal excesses and losses.

Now is the time to start collecting phenotypic data on other economically important traits, such as feed intake. Feed intake may not be completely useful by itself, but feed intake is the cornerstone for many measures of cattle efficiency. Measuring efficiency across the entire integrated beef system is not easy due to the differing classes of cattle (calves, yearlings, and mature cattle), breed differences, and ways in which cattle biological systems (nutrition, reproduction, lactation, basal metabolism) interact.

Cow efficiency is traditionally defined as the pounds of calf weaned per pound of cow weight. Perhaps a more effective way to maximize production system efficiency is to improve feed utilization of grazing cows in the reproductive herd. Considering total herd production efficiency, 65 percent of the feed energy is utilized by the reproducing cow herd as opposed to the growing cattle in feedlots. However, because the cowherd primarily consumes a forage-based diet, it is difficult to measure feed intake for grazing cattle. Therefore, identifying efficient animals based on indicator traits in cattle fed primarily a grain based diet would be ideal.

Traditional measures of feed efficiency in fed cattle include feed conversion ratio (FCR) defined as the amount of feed consumed divided by live weight gain. The broiler industry has been successful at improving feed efficiency by emphasizing selection for FCR to produce faster growing birds. The swine industry has also been successful using FCR, where the majority of genetics provided to this market originate from only three to four suppliers. However, because of physiological differences between cattle and other protein producing species, the beef industry has not been as successful at improving feed efficiency through selection for FCR. Efficient cattle with a lower FCR show a correlated response in increased growth rates, mature size, and maintenance requirements. While FCR is a useful management tool when evaluating the economics of growing and finishing cattle, it is not a good indication of feed production system. Annual feed costs for the cow herd represents 60 to 70% of total costs per year.

Residual feed intake (RFI) is another measure of feed efficiency and can be used as a selection tool to genetically improve seedstock and slaughter animals. RFI was first proposed by Dr. Robert Koch in 1963 in growing beef cattle and is defined as the actual feed intake minus expected feed intake based on maintenance and production requirements. RFI is phenotypically independent of growth rate and body weight. Efficient animals have daily intakes less than predicted after accounting for production and body weight. Inefficient animals have daily intakes more than predicted after accounting for production and body weight. Brangus heifers classified as efficient RFI heifers measured at Auburn University ate 459 pounds of feed less than the Brangus heifers classified as inefficient RFI heifers. This translates into a $75 difference in feed cost over 70 days. Additional research indicates females classified as efficient as yearlings also are efficient as mature cows, thus suggesting feed costs are less for these females throughout their lifetimes.

Another measure of efficiency is residual average daily gain (RADG). Residual average daily gain is the difference between actual gain and predicted gain based on feed intake, body weight, and composition. Animals with a positive RADG gain weigh more than predicted and are considered more efficient.

Researchers have argued as to which measure of efficiency is ultimately best for selection decisions. However, individual feed intake and weight gain is needed for FCR, RFI and RADG. Based on research studies, the Beef Improvement Federation (BIF) recommends contemporary groups be measured for individual feed intake and gain postweaning. Animals must be at least 240 days of age at the beginning of the evaluation. However, animals need to complete the evaluation by 390 days of age. Currently, BIF recommends animals should be fed free choice (minimum 2.4 Mcal ME/kg DMI for bulls) for 70 days after a 21-day adaptation period. Several research studies in Australia, Canada and the United States have found individual feed intake can be accurately determined by 45 days of feeding. However, it takes 70 days for an accurate determination of average daily gain. Currently, there are two technologies available to measure individual feed intake. Animals need to be trained to individual feed gates and daily feed intake measured or an automated feed intake measurement system be utilized. Use of electronic ear tags allow individual animal feed intake to be recorded to a computer using the automated feed intake measurement systems.  Either of these systems can be installed on individual farms, but more realistically, contemporary groups would be measured at centralized testing locations.

Cow efficiency has been a topic of conversation for many years. Ideas, from choosing cows that wean 50 percent of their weaning weight, using feed conversion ratio or dry matter intake, have been suggested as selection criteria. However, for all the talk generated concerning efficiency the last 20 years, there is little to no evidence that American beef producers have selected for improved cow or feedlot efficiency. Ultimately, a 1 percent improvement in feed efficiency has the same economic impact as a 3 percent increase in ADG. Isn’t it time to get serious about beef cattle efficiency?