“When heifers (exhibit) a lot of sorting behavior, you get a lot of inconsistencies in what they’re eating,” says Trevor DeVries, assistant professor of animal science at the University of Guelph’s Kemptville Campus in Ontario.
Diet inconsistency that results from sorting behavior can be a particular problem on operations that don’t deliver feed daily.
During a presentation at the 2011 Dairy Calf & Heifer Conference, DeVries showed a PowerPoint slide of heifers eating from a huge mound of feed.
“What do you think that looks like after two days compared to when it was originally offered to them?” he asked the audience. “It’s going to be completely different.
“I see a lot of people feeding heifers (every other day),” DeVries said. “What’s actually left there at the bunk at the end of the day — and even the next day — is completely different from what was offered to them at the very beginning of the day.”
When a lot of variability creeps into heifer diets, it translates into variability in growth of your animals. A lot of feed goes to waste, too, and if ambient temperature is high, heat damage and spoilage can occur. Heifers that do a lot of sorting also run the risk of developing subacute ruminal acidosis, DeVries said.
In addition to fresh feed, DeVries suggests giving heifers ample bunk space to minimize sorting. Follow these target recommendations from the Dairy Calf & Heifer Association’s Gold Standards II:
a. 6 to 12 months of age: 18 inches per head.
b. 12 to 18 months of age: 20 inches per head.
c. 18 months of age to freshening: 24 inches per head.
d. 3 weeks prior to freshening: 30 inches per head.