Most everyone can agree that the calves are healthier in the pre-weaning stage when fed more aggressively.
This past September, at the annual meeting of the American Association of Bovine Practitioners, researchers from Cornell University reported that calves did well on a 28 percent protein, 20 percent fat milk replacer at 2.5 pounds of dry matter daily. In fact, they were better able to withstand a disease challenge than calves fed a 20:20 milk replacer at 1 pound of dry matter daily. Following experimental infection with Cryptosporidium parvum, calves fed the 28:20 milk replacer maintained better hydration, overcame diarrhea faster, grew better and had a higher feed-conversion rate than the calves fed the conventional diet. The better-fed calves gained 433 grams per kilogram (of milk replacer ingested) per day, while the conventionally fed calves lost an average of 48 grams per day over the three-week period.
It shouldn’t come as any surprise that the better-fed calves are better able to respond to a disease challenge.
The calf’s immune system has an innate requirement for glucose or energy, according to Tom Earleywine, director of nutritional services at Land O’Lakes Animal Milk Products Company. The immune system may not get the energy it needs when calves are limit-fed the way they are on many operations. Then, when an immune challenge occurs, “these calves struggle to respond to it,” Earleywine says.
Feeding calves to a higher plane of nutrition can help. In a study done by the National Animal Disease Center, calves fed 1 pound per day of a 20:20 milk replacer were hypoglycemic, or low in blood glucose. Those calves fed 2.5 pounds per day of a 28:20 milk replacer, meanwhile, had blood glucose levels in the normal range.
Last August, the U.S. Food and Drug Administration came out with regulations that will make it more difficult to use antimicrobials in milk replacers.
“The better option,” Earleywine points out,” is to provide the proper plane of nutrition in the first place so you don’t need (to rely on the antimicrobials).”