Cryptosporidium parvum quietly steals profits, limits calf potential

Unless you have been closely monitoring weight gains and feed efficiency in your calves, you may not realize something is holding them back from their real growth potential.

The cause may be Cryptosporidium parvum (C. parvum), a parasitic protozoan that can infect many mammals, including humans. C. parvum is a primary cause of scours that infects calves from birth to 6 weeks. About 50 percent of calf deaths before weaning are due to scours. Nearly 25 percent of those are attributed to C. parvum.

Mark Welter, president of Oragen Technologies, Inc., has studied viral agents for nearly 40 years and has developed 12 federally licensed vaccines for swine and cattle. He says the first three weeks are a critical time for calves to become infected.

"The most severe C. parvum cases occur in calves less than three weeks old," says Welter, who created the first Rotavirus vaccine for pigs. "Even after their bout with diarrhea, weight loss can be seen for up to 3 weeks after the infection. Both clinical and subclinical infections are common with many herds experiencing C. parvum infections without showing it."

It's easy to see clinical signs of C. parvum infections: watery, profuse diarrhea; dehydration; and weight lose. Losing a heifer calf to scours, or any other disease, means losing the milk that calf would have produced. Even if the calf survives scours, studies have proven that calves that suffer from scours never catch up to their peers. For instance, heifers that have a bout with scours are three times more likely to calve later than 30 months of age.

Subclinical infections can still be detrimental even though the signs of disease are not very apparent. When C. parvum enters the calf's system, it attacks the stomach lining. This causes inflammation in the intestines that can result in clinical cases. Even if it doesn't go to diarrhea, the calf's stomach is still inflamed and will not be as efficient. Research has shown that calves that double their birth weight in the first 8.5 weeks are more productive over their lifetime.

The health and management of replacement animals are important components of total herd profitability, according to Sheila M. McGuirk, DVM, PhD, and Pamela Ruegg, DVM, MPVM, from the University of Wisconsin-Madison. The productivity of the herd can be negatively impacted by impaired growth of calves, decreased milk production of animals that experienced chronic illness as baby calves, spread of infectious diseases from calves to adult cows, increased veterinary costs and the limited opportunity for genetic selection due to high mortality of replacement animals.

A dairy's already slim margin can take a substantial hit when C. parvum makes its rounds. Welter, who has been researching C. parvum for close to 18 years, estimates this tiny parasite costs dairy producers more than $180 million in North America alone. That estimation could be higher if you consider the profitability lost because calves got off to a slow start.

Management of this disease is difficult because any calf infected with C. parvum is releasing millions of oocysts into the calf's environment. Oocysts are the infectious stage of the disease and can live for months in manure and water.

A new scientific breakthrough is poised to give producers protection from this profit-stealing parasite. Similar to the flu vaccine, Welter has developed a way of capturing killed C. parvum proteins in every stage of its life cycle. The killed C. parvum proteins are in liquid that can be mixed with milk replacer and fed to calves. It allows the calf an opportunity to produce an immune response without really being attacked by the parasite. Then when the parasite is present, the calf will be better able to overcome the disease.

Giving your calves the best start on a productive life, means protecting them from day one. If C. parvum comes through your dairy, your calves will not only lose fluids and weight, but future production too. Since the parasite is highly contagious and surprisingly resilient, it will leach potential production from many animals on your dairy. Welter says his breakthrough technology gives producers an easy-to-administer oral method of protecting young calves from ever-present C. parvum.