Determining Postweaning Feed Efficiency in Beef Cattle

A 10% increase in feed efficiency can mean $28 more per head at harvest, but how can you measure feed requirements for individuals in pen-feeding systems? Try using the Cornell Value Discovery System (CVDS), Cornell’s Danny Fox suggested in a presentation to the Beef Improvement Federation (BIF) audience in Omaha Thursday morning.
	The Cornell computer model accounts for variations in breed type, management and environment as it determines the amount of specific feed ration needed to reach a target final weight and finish. Most value-based markets favor a Choice or higher quality grade, Fox noted, justifying an equivalent 28% empty body fat (EBF) target. Like other default values in the CVDC, that can be adjusted for different targets.
	A frame-score final-weight predictor interacts with formulas for net energy required for gain by stage of growth and such past management factors as wintering or placement of weaned calves directly on feed, and the effect of implant history. The model reconciles total pen dry matter intake, ration and ingredient analysis, pen size, environment and weather with individual starting and final weight targets, breed, sex, frame, implant, projected days on feed and daily gain to account for more than 80% of variation in individual feed efficiency, Fox said. 
	“Producers sometimes wonder if they are being billed fairly in the steer futurities where they pay a share of the pen’s feed bill,” he added. “Our work indicates that with five head or more, there is only a 1% to 2% risk of error.” But big differences in starting weights can still mask individual feed efficiency among five head.
	Without the CVDS and its “DAYSTEP” model component, producers may incorrectly perceive a 1-pound (lb.) difference in feed efficiency between 500- vs. 700-lb. starting weight cattle. The DAYSTEP feature allows comparing for “same-stage growth” by projecting differences in requirements along a growth curve.
	Cornell is beta-testing the CVDS software Version 1.0.0, available via e-mail to Michelle Cole at mlc44@cornell.edu.
— by Steve Suther