As much as we try to avoid having sick cows, at some point or another, we will experience a cow that is feeling under the weather. As much as humans try to refrain from contracting sicknesses, the same goes for cows. While we can run to the store and buy ourselves over-the-counter medicines, it is obvious that the herd doesn’t have the ability to do so. We may rely on our herdsperson or veterinarian to help keep cow health in check, but cows can also fight disease using internal hidden defenses. While these defenses may look like symptoms of sickness, they can also mean that the cow is doing her best to fight off whatever disease has invaded. In an Ohio State Buckeye Dairy News article, graduate research associate Elizabeth Plunkett described what is happening when we notice disease symptoms in our herds.
Keeping disease incidences at minimum is without a doubt one of the biggest goals on a dairy farm, as they can be costly and detrimental to the herd. The good news is cows often tell us that something is wrong simply by the way they act and by milk production. But Plunkett said, “The physiological adjustments present at the onset of disease are a set of highly organized and calculated survival mechanisms that have been evolutionary favored for centuries.” Meaning cows have an arsenal of disease-fighting weapons that require no assistance from humans.
The biggest sign of illness that is often observed is when a cow goes off feed, also known as reduced feed intake. “Although it might appear unfavorable when sick cows stop eating, it is actually a protective mechanism,” she said. While this would normally seem like bad news, it can be a good sign during times of sickness. Listed below are some benefits of reduced feed intake that the graduate research associate highlighted.
- By consuming less feed, less energy is needed for digestion, which is already a energetically costly process. This allows more energy to be redirected toward fighting infection and fueling vital organs.
- Cows may recognize that the cause of getting sick is coming from the feed, so they take a step back and don’t eat as much. This also gives time for the gastrointestinal tract to take a break.
- Mustering up the energy to get up and walk to the bunk may be too much for a cow. It can also take up a lot of energy that they are lacking, which is why they may choose to stay lying down, conserving energy.
- Because cows are grazing animals, they also understand the threats of prey. Of course, when sick you are more vulnerable to prey.
Fever can also be a tell-tale sign of sickness, but it is battling the disease behind the scenes. Cows may spike in temperature to fight off certain bacteria and viruses that may not be able to survive in high temperatures. To maintain a higher temperature, the body needs to redirect heat from certain areas to the area of disease or generate more heat. “For example, sick animals often curl up in an attempt to reduce their surface area or limit heat loss,” Plunkett noted. This explains why we may notice a cow’s ears feeling cold to the touch. She also warned that the body will boost heat production by speeding up metabolism, which takes a large amount of energy. Fever can increase overall metabolism by 30% to 50%, creating more stress if the response is prolonged.
It is important to note that every farm and every cow is different. Some cows’ defense mechanisms may vary from those of another, and some may have different variations of a pathogen. While cows do have the ability to fight off disease on their own, this does not necessarily mean that they don’t need outside help. While these defense mechanisms are biologically normal, their prolonged presence can create just as much damage as the invading pathogen, she noted.
