Johne’s Disease: Managing Manure Exposure Is Key In Containment For Cow-Calf Herds

Apr 14, 2016

By Russ Daly, DVM, DACVPM

Professor, SDSU Extension Veterinarian, State Public Health Veterinarian

SDSU Veterinary & Biomedical Sciences Department

While often considered a condition of dairy cows, Johne’s Disease has increasingly been identified as a concern for beef producers. Animals affected by this disease show signs of diarrhea and progressive weight loss, often in the midst of a normal appetite. These animals are culled from the herd before they become debilitated, but worse yet, they serve as the source of disease to others within the herd.

About the Disease

Since Johnes’ Disease primarily affects the intestine, the causative bacteria (Mycobacterium avium subsp. paratuberculosis) usually leaves the infected animal through their manure. It’s this contaminated manure that serves as the source of bacteria for uninfected cattle. Typically, it’s a young calf that is the most likely to become infected with the bacteria. However, Johne’s Disease is such a slowly progressing condition that signs don’t show up until the animal is much older: often 3-4 years of age or more.

Knowing this, the key to decreasing Johne’s Disease transmission comes down to preventing young stock from coming in contact with manure from potentially infected animals. Of course, this is a task easier said than done!

Protecting Your Herd

While preventing all contact with manure is not feasible in a cow-calf operation, there are some actions that producers can take to reduce this contact. Infectious disease transmission often comes down to a numbers game: the fewer bacteria in a calf’s environment, the lower the likelihood of clinical disease. Anything we can do to reduce these numbers stacks the deck in favor of health over disease.

Calving Areas

The calving area is especially important when it comes to transmission of Johne’s Disease. Newborn calves are particularly vulnerable to the bacteria entering their bodies and beginning the slow steady progression to clinical disease that may appear years later. Risky conditions for calving areas include:

Use by multiple cows at the same time (rather than individual pens)
Manure buildup
Dirty conditions that contribute to soiled udders
Cows with clinical Johne’s Disease or other illnesses nearby or in the calving area

Nursing Calves

As young calves are paired up with their mothers and leave the calving area, exposure to manure remains a threat for the transmission of Johne’s Disease. Conditions for nursing beef calves that contribute to Johne’s Disease exposure include:

Cows with clinical Johne’s Disease running with cow-calf pairs on pasture
Manure buildup
Conditions that contribute to manure contamination of water sources (stock dams and creeks rather than water tanks)
Conditions that contribute to manure contamination of feed (feeding on ground rather than in bunks or feeders)
Cows sick from other illnesses running with cow-calf pairs on pasture
Use of equipment (skid steers, loaders, etc.) contaminated with manure from the cow herd

Newly Weaned Calves

As cattle get older, their resistance to new infection with Johne’s Disease bacteria increases. However, even weaned calves can become infected, particularly if exposure levels are high. Because of the typical long incubation period of Johne’s Disease, newly weaned animals destined to become replacement females or bulls are the group of animals of most importance. Conditions that increase the risk of these animals to become exposed to Johne’s Disease bacteria include:

Close proximity to or running with the cow herd, particularly if animals affected by Johne’s Disease are present
Conditions that contribute to manure contamination of water sources (stock dams and creeks rather than water tanks)
Conditions that contribute to manure contamination of feed (feeding on ground rather than in bunks or feeders)
Manure from the cow herd spread on pastures or forages used that same season
Use of equipment (skid steers, loaders, etc.) contaminated with manure from the cow herd

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