What is the most common cause of diarrhea in baby calves?

E. coli, you say? Probably not. Although bacteria, especially E. coli, are likely to contribute to disease, the most likely inciting factor for diarrhea in 1- to 3-week-old calves is Cryptosporidia parvum, or “crypto.”

Crypto is a coccidia-like organism for which there is no vaccine or effective treatment. Infection is common in young calves. The organism has been detected in 70 percent of 1- to 3-week-old dairy calves based on a single examination of feces. In a sampling of over 1,100 farms, infection was found on 59 percent of the farms and 22 percent of the calves. In the first 4 weeks of life, the prevalence of infection may reach 100 percent. (Garber LP, 1994; Radostitis OM, Gay CC, et al., 2000)

The organism is readily transmitted by the high numbers of organisms shed in the feces of infected calves. Shedding is reduced as calves develop immunity and is less common and intermittent in older calves and adult cattle.

The occurrence and, particularly, severity of disease following infection will depend on the extent of infection and the presence of other pathogens (e.g., bacteria, such as E. coli or salmonella) as well as other stressors (e.g., environmental factors).

Prevention is difficult and is dependent on minimizing transmission. This involves strict sanitation in calf-rearing facilities for dairy operations. For beef cattle, cows should be on uncontaminated pasture for the birth of the calf and for at least the first two weeks of the calf's life. Strategies for cattle movement to minimize exposure during the first critical month of life have been devised.

Consult your local veterinarian for help in adapting farm facilities to minimize the risk of infection by Cryptosporidia parvum.