A simple step-up in nutrition — the difference between a 20:18 milk replacer and a 22:20 milk replacer — has paid off big time for Dream Farms in south central Pennsylvania.

The 6,500-head custom calf-raiser ran an experiment a year or two ago, comparing growth rates in animals fed the different milk replacers. It was visually apparent that the 22:20-fed animals were bigger, says farm manager Lane Sollenberger. For one thing, they were about 1.5 inches to 2 inches taller, with increased skeletal development.

Between one day of age and 60 to 65 days of age, the 22:20-fed animals gained 0.5 pounds a day more, on average, than the 20:18-fed animals. 

“There’s no question these calves are a lot healthier,” Sollenberger adds. Treatment costs for such things as scours and respiratory disease have gone down.

There’s a growing consensus that calves fed to a “higher plane of nutrition” are healthier than their conventionally fed counterparts. 

Does it pay in the long-run?

Any disagreement over feeding calves more aggressively is not their health status, but rather the growth advantages — and whether those growth advantages carry over to later stages of life. It really depends on how you feed the animals post-weaning.

Recently, researchers from the United Kingdom studied the impact of protein concentration in milk replacers on animal performance. Calves fed 2.64 pounds per day of milk replacer containing 27 percent crude protein gained 0.35 pounds per day more during the pre-weaning period and were 20 pounds heavier and 1.2 inches taller at weaning than calves fed 1.32 pounds per day of a 21 percent protein milk replacer. Yet, “differences in live weight and body size due to feeding level disappeared by day 90,” according to an abstract of the study from the November 2009 edition of the journal Animal. 

That particular study followed the animals through their second lactation and did not find any milk-production advantages in cows that were fed more aggressively as calves.

Yet, other studies have been more optimistic about the long-term effects. Mike Van Amburgh, animal scientist at Cornell University, was the first to follow aggressively fed calves all the way through their first lactation. Sixty-five heifers fed high-protein milk replacer during the pre-weaning phase ended up producing 25,047 pounds of milk during their first lactation, on average. That is 88 percent of the milk given by their mature herd mates — those in their third lactation or beyond. Under most circumstances, a person would be happy if the first-calf heifers’ milk production approximated 83 percent to 85 percent of the milk given by mature herd mates. In Van Amburgh’s study, the heifers exceeded that.

Other studies have supported that conclusion. 

Again, different studies use different protocols, with post-weaning feeding a critical variable.

Healthier calves

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. 

Final points

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).”