Functional Proteins: More Than Just Building Blocks

Some proteins do more than just help build and repair tissue. In fact, some perform essential functions within the body before they are ever digested.

Dairy farmers know that providing adequate dietary protein is essential to herd health and production. These substances are essential building blocks for creating and repairing body tissues, including muscle, skin and hair. Producers carefully balance the ration to provide adequate protein to their cattle to maximize milk and milk protein production.

Traditionally, dietary proteins have been viewed as pretty much the same animal: a chain of amino acids, broken down into individual amino acids by digestion, absorbed into the body, then resynthesized into animal protein such as muscle or milk protein. Dietary proteins are generally measured by determining the amount of nitrogen in any given cow feed, according to Jim Quigley, Ph.D., Vice President and Director of Calf Operations for APC, Inc. The amount of nitrogen is then multiplied by 6.25 to come up with estimated overall protein content. The structure of the protein being assessed is rarely taken into consideration.

But, it’s not that simple. Proteins vary widely in structure, and some perform functions in the body, over and above providing much-needed amino acids, says Quigley, who earned his Ph.D. in animal science at Virginia Tech.

Increasingly, dairy producers realize that these “functional proteins,” have important biological effects in the animal before the protein is even digested. And, while relatively few proteins fall into this category, those that do are important, either because of advantages they can provide, or because of difficulties they can cause.

“Milk, for example, contains a functional protein called lactoferrin,” Quigley explained, “which works as an antimicrobial in the intestine when the animal eats it.”

That function is important, particularly for calves, because unlike the mature cow, the young calf ’s digestive system is monogastric. Equally important, the immune system of calves is not mature, Quigley added.

“So, if we can find some functional proteins that support the immune system, then we can usually accomplish some really good things.”

On the other hand, some proteins can create problems in certain animals.

“If you feed a pig (or monogastric animal) unheated soybean meal, a protein in soybeans called trypsin inhibitor can bind to the enzyme trypsin and interfere with the digestion of protein,” Quigley offered. “That can have a negative effect on growth and efficiency and can even cause scours. That’s why we always heat soybeans to destroy the trypsin inhibitor before feeding them to pigs.”

The soybean example is less applicable to cows, as bacteria in the rumen usually break down trypsin inhibitor. For dairy farmers, one of the most important tasks that functional proteins perform is in the development of the calf ’s immune system before it has developed immunity to various disease threats.

The number one source of immunity for young calves is the colostrum that cows produce at birth. Colostrum contains a host of disease-specific antibodies that provide immune support in the calf ’s intestine, even before they’re absorbed into the blood stream.

The number one source of immunity for young calves is in the colostrum cows produce immediately before and after birth. Colostrum contains a host of disease-specific antibodies that start providing immune support in the calf’s intestine, even before they are absorbed into the blood stream.

“These antibodies work by helping the body identify pathogens,” Quigley explained. “Every bug that causes disease in calves, (e.g. E. coli, Salmonella spp., rotavirus, etc) has different components that are identified by antibodies in colostrum. Those antibodies flow downstream, and if they find the bug they are designed to find, they attach to it. The invading organism then may not be able to attach to the wall of the intestine, so it is not able to cause disease. It simply flows downstream and ends up in manure.”

Most dairy farmers feed colostrum for the first 24 hours, but Quigley says the immune properties in colostrum can provide real value in terms of calf health when that time frame is extended to 3-5 days after birth.

Further, this enhanced immunity can reduce the use of antibiotics, thereby saving money on drugs and reducing the risk of antibiotic resistance. As Quigley puts it, “If you use natural antibodies instead of antibiotics, you can save the antibiotics for use when they are really needed.”

Moreover, this approach can help dairy operations meet increasing consumer demands for more natural animal products. And, using colostrum more extensively can help producers comply with new FDA (Federal Drug Administration) guidance to limit the use of prophylactic antibiotics in livestock operations. Dairy farmers, for instance, are subject to new regulations limiting the use of antibiotics in milk replacers.

Of course, collecting colostrum and mixing it with milk replacers requires labor and equipment for storage and refrigeration. If such a process is not feasible, given operational limitations, antibodies can also be obtained from other products that boost immunity.

Spray-dried egg powder is derived from the eggs of chickens that have been vaccinated against specific diseases, so the chicken makes antibodies that are passed on in their eggs. The powder, which is added to milk replacers, can be purchased in disease-specific varieties to meet the individual needs of dairy operations.

Antibodies can also be acquired from spray-dried animal plasma and serum derived from beef cattle. It comes in a powdered form and can be added to milk replacer formulas at a rate of approximately 4-5 percent.

“If you are a dairy farmer, the cheapest source of functional proteins is the extra colostrum the cow makes,” Quigley said. “So, as soon as the cow gives birth, feed that first colostrum to the calf straight away,” he advises. “But, the next couple of days’ milk also has value as a source of functional proteins, and it’s the cheapest source. So, add the second, third and fourth milking from the cow to milk replacers as a source of functional proteins.”

After colostrum, the next cheapest source of antibodies is spray-dried animal plasma. Quigley advises providing it with milk replacers until the calf is weaned. New processing technologies allow manufacturers to create plasma proteins that are highly soluble, light in color and provide a high degree of functional protein to support calf health.

“These are economical products that any feed manufacturer offers,” Quigley said. “If you are having health problems on the farm, using these products should deliver a significant improvement right away.”