Calf Scours Causes

Calf recovered from scours

Healthy calf again after suffering from scours

The Most Common Causes of Calf Diarrhea

Calf scours is a general term that refers to a calf having a very loose stool. This symptom is common to a variety of illnesses and conditions. In other words, scours itself is not a disease, but a digestive issue resulting in diarrhea that can be caused by a number of different things. Plus, calf susceptibility varies as they develop, so causes tend to change as a calf grows. While scours has a low mortality rate, it can severely impact growth and development (meaning more food to produce less cow), plus be expensive to treat. Understanding root causes is the first step to prevention.

Two Categories for Causes of Calf Scours

Let’s divide the causes of calf scours into two broad categories. The first is a digestive issue that is associated with food and/or feeding methods – sometimes called nutritional or non-infectious scours. The second category is a digestive issue caused by an illness or a reaction to bacterial, viral, or protozoan (digestive microbial parasite) infection known as infectious scours.

Nutritional Causes of Calf Scours

Issues related to nutrition and feeding are a well-recognized cause of calf scours. The digestive system of a calf is not fully developed, and feed content and methods that are disruptive during digestive development can cause diarrhea. Since this is one of the most preventable causes of scour, it would be worth consideration if scours is an issue.

Two common causes of scours associated with feeding are:

  • Inappropriate feed or feed mixture for the age of the calf
  • Sudden changes in feed

For example, early access to water and forage aids in the proper development of the rumen (first stage stomach) and the friendly bacteria and protozoa that it needs for proper digestion. Otherwise, during weaning, the calf is not ready to properly digest the food that takes the place of milk. This, in turn, leads to the calf consuming more milk when it should be consuming less – resulting in loose, whitish stools from undigested milk.

While there are some common feed-related causes, there are an infinite number of feed and nutrition issues that can cause diarrhea. Finding a root cause should start with the obvious, but it may require looking beyond the most common issues. There can be additional concerns with scours if un-pasteurized waste milk is used in feeding.

Infectious Causes of Calf Scours

The second major cause of calf scours is a bacterial, viral or protozoa infection. Generally speaking, a normal healthy calf in a normal environment would not typically be affected by everyday exposure to common microbial threats. Two conditions, however, lead to calves succumbing to an illness that in turn causes diarrhea.

- An underdeveloped immune system is one common reason calves are unable to cope normally with common microorganisms. An undeveloped immune system may be associated with the calf not receiving enough colostrum during the first few hours of life. It is only during the first 4-8 hours that a calf is capable of receiving and incorporating the all-important antibodies the mother passes along in her first milk for the calf to build its own strong immune system. Without a strong immune system the calf is much more susceptible to becoming ill and having loose stools. In-breeding is also associated with underdeveloped immune systems.

- Immune system overload is also a reason calves get ill and develop scours. Even a healthy calf that is overexposed to harmful microbes will eventually succumb. As the immune system is occupied fighting off one or two bacterial or viral infections or parasites, it is exposed to several more as well. Eventually the immune system is overwhelmed and the calf becomes ill. The viruses and bacteria that cause sickness tend to thrive in wet, cool, muddy conditions, which is an accurate description of many lots during spring. If the environment becomes extremely friendly to harmful microorganism then a significant number of calves may get sick and display scours symptoms.

Some established remedies to reduce infectious scours include ensuring calves receive an adequate volume of colostrum by using a bottle or a feeding tube during the first few hours of life. Additionally, reducing exposure by separating young calves from the general population, who can be carriers of harmful microbes, has shown to be effective.

Whatever the root cause might be, the end result is that a calf with scours is not getting the best possible nutritional benefits from feed because its digestive system is not functioning properly. Poor nutrition means poor growth and less return per calf. Dehydration that commonly accompanies scours is also a cause for concern since it is the leading of cause of death for calves with scours.

The most effective and efficient approach to resolving calf scours is through preventive action that address root causes. In any large population of animals, a small number are bound to get sick and display symptoms like diarrhea. When scours starts to affect a significant number of calves, however, then identifying the cause or causes is a critical step in finding a remedy.

Discover how you can treat and cure calf scours in your herd and how you can prevent new outbreaks without much effort. You can download my three free reports on the causes of calf scours and stay informed about new developments.


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