How to keep your dairy cows chill

Chronic stress underlies many health challenges in dairy cattle, but it can be the catalyst to death. Stress is one of the driving reasons Hemorrhagic Bowel Syndrome (HBS) sneaks up on many dairy producers. 

Experts say it can be hard to pinpoint the exact cause of HBS — also known as the silent killer in cattle — because it can be a combination of stressors, including nutritional.

HBS is sporadic, says Dr. Scott Bascom, technical services manager for Phibro Animal Health. Farms can go months from seeing signs of cows suffering to cows dying within a week or two. In 2014, USDA reported that 14% of herds identified HBS as a problem.

Bascom says that percentage might not seem high enough, but it is significant that 80% of the 14% were removed from the herd due to culling from symptoms or died. As a silent killer, HBS is deadly in herds because there is no treatment or cure, so producers need to be vigilant in prevention.

Stress can be complicated in cows, just like it can be in humans, says Chris Gwyn, sales director for Jefo Nutrition Inc. There are more than 30 stress causes that dairy herds can experience. The most common sources are transition periods — calving, early lactation, drying off, weather conditions such as heat or cold temperatures. Cows can also experience stress from management decisions; stocking density in barns and changes in diet can lead to metabolic and gut health-related challenges such as ketosis or acidosis.

Cows can usually overcome one stress, but not multiple stressors. That's how HBS can appear in cattle, especially if the stressors trigger a metabolic or gut-related matter, says Gwyn. 

"The more stressors cows have will wear the immune system down. A cow will become more sensitive to diseases such as metabolic types," Gwyn adds.

HBS is often diagnosed in cows in the early lactation stage, in high-producing cows, or in cows with immunosuppression caused by stress. Healthy cows or low-stress cattle are resistant to HBS, says Bascom.

"It all hinges on a strong immune system," he adds.

Know the stress!

Cows, like humans, will often express symptoms of stress through body language. Cow behavior is a telltale sign of the type of stress they are experiencing, says Carly Becker, a dairy cattle specialist with Pennsylvania State University Extension. For example, cows will increase their standing time in hot temperatures, pant, or hang their tongues out.

One of the first characteristics of nutrition-related stress is the cow will go off feed, followed by no energy, and ears pinned back. During times of stress, high-producing cows will lose body condition. "The ribs, hooks, and pins will become more prominently visible," Becker adds.

One hint that a cow could be suffering from HBS: loose manure with specks of blood, says Bascom. 

Keeping disease and stress away with diet 

Producers have access to tools and management decisions to mitigate stress in a dairy herd. The most important is keeping cattle on a well-balanced diet. 

A well-balanced diet requires consulting your nutritionist to ensure the herd is eating a diet that supports their nutritional needs through lactation cycles, says Gwyn. That includes updating feed — the total mix ration with fresh and fermented forages of silage, along with quality byproducts of corn, proteins, minerals, and vitamins. "When the ration on paper doesn't match up in the cow, or if cows can't consume the calculated ration, that's where your trouble starts," Gwyn says.

Corn silage is a primary component of a ration; it's also susceptible to fungus and molds that can cause illness, which can stress a cow's immune system. Bascom says aspergillus fumigatus, an invasive fungus, can be commonly found in silage because of improper packing and storage.

Experts theorize that Aspergillus fumigatus could be a contributor to HBS. Research from autopsies — the only approach for farmers to truly know a cow suffered from the disease — found DNA from aspergillus fumigatus in the tissue of dead cattle.

Besides silage quality, deficiencies in vitamins and minerals can also cause stress and a flare-up of HBS in cows. As a cow approaches a transition phase, to combat that period of stress, farmers can increase supplements of pro-active amino acids, A and B vitamins, and selenium, which boosts immune system defenses, says Gwyn.

There are various supplement products that farmers can use, says Bascom. For example, Phibro's OmniGen and Jefo's Vicomb are supplemental mineral and vitamin mixtures to help farmers improve immune function.

Another key to keeping a herd on a well-balanced diet is ensuring all the cows have access to feed. Farmers should check barns to ensure the technology, such as a feed pusher, works appropriately and keeps feed and water accessible 24/7. "The recommendation for a free stall barn is that feed needs to be pushed six to seven times a day," says Becker.

Gwyn adds that farmers could also check in on moderate-producing cows. Those animals are probably encountering obstacles that keep them from taking in adequate amounts of feed to become high-producing cows.

Management to reduce stress

According to Becker, farmers can also focus on cow comfort, which means limiting or avoiding overcrowding in pens.

"There's a hierarchy in cow herds. Bully cows will push the more submissive-personality cows around, leaving them standing more while laying down and taking up available space," she adds.

Farmers can also increase cow comfort by having 3 to 4 inches of sawdust on the mattress. "It adds that extra cushion," Becker says.

Management to reduce stress in a herd can be hard to balance for farmers, but it is achievable. Gwyn says he knows of high-producing herds that have found methods to reduce stress with cow comfort management and tools that help keep rations current.

A stress-free cow

What does a stress-free cow look like? It's simple. She’s relaxed, calm, and chewing cud in an idyllic manner. She spends more time lying down and dozing off. Gwyn says he can tell when he's working with a relaxed herd when he can approach a cow in their blind spot and still be able to work with them.

Stress and some of its impacts are manageable with consistent attention and stewardship.

"It's about ensuring everything around the cows is not stressing them out. Challenges will pop up, but knowing the signs of stress will help farmers keep it under better control," says Gwyn.