Biosecurity in the Cow-Calf Industry

Exploring Johne’s Disease

Introduction

A survey¹ of Western Canadian cow-calf producers revealed that few producers ask about disease history of the animals when purchasing, most producers do not clean equipment after handling manure, and most use the same equipment to handle feed and manure. With the emergence of new diseases and the increased threat of diseases entering the country (e.g. Salmonella Dublin, foot and mouth disease), improvement of biosecurity practices on beef farms is critical. 

This FAAST review will highlight the key components of a successful beef cow-calf farm biosecurity program, using Mycobacterium avium subspecies paratuberculosis (or Johne’s disease) as an example.

What is Johne’s disease?

Johne’s disease is a bacterial disease caused by Mycobacterium avium subspecies paratuberculosis (MAP), and is frequently found in Canadian beef cows. In 2014, a study of Alberta beef herds found that 20% of herds had at least one cow that tested positive for MAP. Of those herds that were infected, 22% of cows within the herd tested positive for the disease². 

The introduction of MAP into a cow-calf herd can have significant economic and animal health impacts. Adult cattle can develop long-standing diarrhea and weight loss, which leads to premature culling and reduced slaughter value, costing beef producers approximately $75 to $100³ per infected animal. 

Although the impact of MAP on the health and welfare of cattle is significant, most Canadian beef herds are not infected with MAP, and those that are, tend to have a low number of infected animals within the herd. Because of this, implementation or improvement of biosecurity practices can go a long way toward minimizing infection risk and impact.

Biosecurity and MAP

MAP causes a long-standing infection in the digestive tract of cattle, resulting in diarrhea and emaciation because nutrients cannot be absorbed. MAP can be silent for 2 to 10 years after infection before cattle show clinical signs, known as Johne’s disease. 

Infected cows shed MAP into their environment via manure/feces when the infection is “silent” and when it is clinical. The bacteria can be spread through fecal-oral transmission, or ingestion of milk and colostrum from infected cows. Newborn calves (within 24 hours of life) are most susceptible⁴ to infection, but calves less than 6 months of age are also at an increased risk. 

External Biosecurity

Pastures and Introduction of Animals

The best way to prevent MAP in an uninfected herd, is to avoid the introduction of disease positive cattle⁵. MAP infected cattle can look healthy while shedding high-levels of bacteria in their feces. Therefore, if animals are purchased, they should come from known disease-negative herds and blood or fecal samples should be taken to test each animal for infection before the animal is integrated into the herd. 

MAP can survive for up to 55 weeks in some environments⁶. Healthy cattle sharing pasture with cattle that are MAP positive can result in disease transmission. Ensuring that cattle of other herds have not had access to the pasture or housing that you will use for your animals is important in preventing MAP transmission.

People, Vehicles, and Equipment

Humans, vehicles, and equipment can potentially act as MAP carriers and add to overall disease risk. To prevent the introduction of MAP on your farm through these routes, biosecurity signs and warnings should be posted and visitors should wear clean boots and clothing (i.e. not contaminated with manure). Vehicles and equipment should be routinely cleaned and disinfected. How? Wipe and scrub all organic material off of the surface, rinse with hot water and soap, followed by the use of an appropriate disinfectant. Always read and follow the label of disinfectants to ensure they are used appropriately. 

Internal Biosecurity

Management

Calves are the most susceptible group to MAP infection; therefore, controlling MAP in a farm population starts with limiting calf exposure to the bacteria. Monitoring and careful management of environmental, feed, and water contamination can lower the exposure of calves to cow feces and lower the risk of MAP transmission from cow to calf.

The area where calves are born and nursed during the first few months of life is important to consider. Enlarging this overall area, having multiple access points to water, and moving the cow feeding areas frequently (even daily), can prevent feed and water areas from becoming muddy and contaminated with feces. These practices can further lower the risk of MAP transmission by reducing calves’ risk of coming into contact with contaminated teats and udders. In herds that have infected cows, research shows that MAP is often present on udders of cows that are uninfected when poor sanitation practices are employed⁵.

Another strategy to consider is a test-and-cull program. Infected animals within the herd can be identified by blood or fecal testing all adult cattle. Animals with a positive blood or fecal test result are likely shedding MAP into the environment, and are potential candidates for being culled. Calves from infected dams should not be retained for breeding stock, as they are likely to be positive as well based on MAP transmission occurring from cow to calf in utero, through colostrum or milk, and through the fecal-oral route⁵.      

Cleaning and Disinfection

The area that requires the highest level of cleanliness is the calving area or the area where calves are kept in early life. Preventing manure build-up in the calving area, and avoiding the use of a calving pen that is shared between sick and lame cows, will help reduce environmental exposure to MAP^7,8. Cleaning and disinfecting the calving pens frequently and ensuring they are clean and dry will aid in reducing transmission to youngstock.   

Personnel

The personnel working with cattle are ultimately responsible for implementing the management changes to best control MAP. That is why it is critical to ensure that each person on the farm that works with cattle understands why these practices are being implemented and buys into the system. Your veterinarian may be an excellent resource to help in training staff and helping personnel with understanding the “why” of each management practice.

Take Home Messages

Mycobacterium avium subspecies paratuberculosis, the causative bacteria of Johne’s disease, is common and costly on beef cow-calf farms in Canada. Similar to other infectious diseases, the best option to prevent these bacteria from entering your farm is to refrain from purchasing and introducing potentially infected animals to your herd. This disease can be controlled using a combination of management strategies and test and cull options. 

Work with your veterinarian to determine the best strategy to prevent, or control, MAP on your farm.