High grain prices and cost of gain in the feedyard have driven recent interest in managing cattle to heavier weights on forage, followed by shorter finishing periods on grain-based rations.
Research results from Kansas State University indicate that heavy cattle placed from stocker programs can perform well and produce acceptable beef with as little as 75 days on feed. But to reach their optimum in terms of marbling and fat color, they need more time in the feedyard.
The K-State researchers brought 144 crossbred steers into the feedyard weighing an average of 955 pounds, and randomly assigned them to pens for either 75, 100 or 125 days of feeding. The researchers monitored performance in each group, collected carcass data at slaughter and used sample steaks from each group to evaluate tenderness based on shear force and meat palatability using a trained panel of taste-testers.
As you might expect, increasing days on feed from 75 to 100 and 125 days increased total weight gain but did not significantly change average daily gain, average daily dry matter intake, or gain-to-feed ratio, so production efficiency was about the same for each group.
Increasing days on feed from 75 to 125 days increased hot carcass weight, 12th rib fat thickness, ribeye area, and marbling score. Increasing days on feed from 75 to 100 days improved marbling scores, but marbling scores did not improve significantly between the 100-day and 125-day groups in this trial. The longer feeding period did not affect dressing percentage, yield grade, or percentage kidney, pelvic, and heart fat.
Increasing days on feed from 75 to 125 days did not affect lean color, but fat color changed between 75 and 100 days on feed, with external fat from the 75-day cattle having a higher prevalence of yellow fat and that from 100-day cattle becoming whiter in color, which is desirable for consumers.
The researchers report no significant differences in most sensory traits or instrumental tenderness as a result of increasing days on feed, although sensory panels did find more off-flavors in samples from cattle fed 125 days compared to 100 days.
The researchers conclude that producers can place heavy yearling stocker cattle on high-concentrate diets for a minimum of 75 days with minimal changes to performance, efficiency, and sensory traits,
but heavy yearling cattle should be fed for a minimum of 100 days to optimize marbling score and white external fat color.
The full report is available online from Kansas State University.