Feed Lot

DEC 2017

Feedlots and cow/calf operations in the beef industry who feed 500 or more has annually on grains and concentrates; maintain 500 or more beef cows; backgrounder, stocker/grower, preconditioner; veterinarian, nutritionist, consultant

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he performance of healthy cattle on feed is "extreme- ly predictable," but you have to know what to expect and when to worry. That's according to Richard Zinn, University of Califor- nia-Davis animal scientist, who pre- sented at the late summer Feeding Quality Forum in Omaha, Neb., and Garden City, Kan. Large-scale cattle feeding is only practical because scientists learned what to expect and shared knowl- edge with the industry, he said. Over the years, rules of thumb as precise as slide rules moved from experi- ment stations to feedyard man- agers' notebooks and computers. "We have a sense of certainty from looking at millions of num- bers, so if a number isn't what we expect, there's a problem, and we can look for areas of opportunity," Zinn said. "It boils down to confi- dence. But there's risk and that's inversely proportional to confi- dence. The greater the risk [sick- ness, environment] the more we pay attention." The most predictable situations can be confused by assumptions like pencil shrink, poor weighing conditions or simple errors in recording data on the wrong line or wrong sex of the cattle. "I look at tens of thousands of closeouts, but discharge 3% to 5% because the numbers aren't just improbable—they're impossible," Zinn said. There's real variation that goes against the norms, he said, noting the main one is extreme weather at closeout. Space allowance per animal is another factor, with per- formance dropping off when that gets below his recommended 130 square feet. Differences in shade, shelter, feed additives and implants tweak expectations but can be fac- tored in. Changes in energy density of the ration affect feed efficiency as do shifts in starting weight and car- cass weight. "If you're only looking at aver- age daily gain and feed efficiency, you're going to be misled in terms of how well the feedlot is actually performing," Zinn said, suggesting a closer look at the energy compo- nent of dry matter intake. "The re- lationship between energy intake and growth performance is almost certainly the most reliable of nutri- tional concepts." That relationship is critical to profit as well. A model that ac- counts for gender, frame, quality, in-weight and energy value of the diet can reliably predict outcomes for average cattle. "Deviations would be areas for the feedlot to look at why perform- ance is not this number right here," Zinn said, noting the predictability 12 FEED•LOT  December 2017 FEEDLOT FOCUS Expectations guide cattle feeding By STEVE SUTHER T given accurate input to the model or formula. But what happens if en- ergy intake varies? One example showed the im- pact of a 2% increase in energy in- take added $9 per head on the final close-out. Further implications support industry efforts to en- hance that intake, and Zinn ana- lyzed a feed additive example that came in 3.3% above average: 40% due to an increase in dry matter intake and the rest from improved energy utilization. He closed with a mystery solved regarding varied results linked to specific pens within feedyards. He knew that pens encountering the most feed-truck traffic tend toward lower performance from that low- level stress. But a very large feed- yard was dismayed that its new ad- dition at the far end of the facility rarely beat average performance. A study of daily feed logs and other factors showed those pens were always fed last, so every mi- nor breakdown over a year of feed- ing came to bear on that area. "If there was ever a problem with electricity going out or a storm, or whatever, performance in those cat- tle took the brunt of it," Zinn said. "So we discussed some ways they could mollify that challenge. But it's good to know all the potential sources of variation when you want to determine what to do." FL

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