For the past few years, drought conditions have affected producers and cattle across several regions. Typically, cattle can survive a year-long drought, and the environmental and nutritional stress, and have enough reserve to bounce back. However, when the stress continues during multiple seasons, their reserves are drained.

Under these circumstances, calf health and performance can be less predictable. Producers can still do everything right to help mitigate loss – low-stress cattle handling, utilizing a solid vaccination program, diligent observation for disease – but droughts change the game. What were successful practices in the past may not be sufficient to prevent outbreaks today.

The cow, the calf and the fetus

When looking at the life cycle of cattle, we are managing a cow, a calf and a fetus at any point in time. During a drought, cattle do not get access to the normal levels of micronutrients and macronutrients because of changes to the source of their food, causing deficiencies in the cattle’s diet.

If supplemented feedstuffs come from different sources and are not tested, cattle may not be getting the nutrients that producers think.

During the pregnancy stage, the cow’s immune system serves as a barrier between diseases of the herd and fetus. When the cow’s immune system cannot respond to diseases, the fetus becomes more susceptible.


We begin to see higher rates of illness, such as bovine viral diarrhea virus (BVDV), which can have a detrimental effect on the fetus’ immune system. A malnourished fetus will be a malnourished calf and is less likely to have the ability to deal with stress and disease.

Dietary stress remains an issue once the calf is born. A cow’s first priority is basic life support. Second is providing for the pregnancy, followed by lactation and growth.

Over a period of time, protein and mineral deficiencies will show up in the cow’s ability to mount an immune response, and the nutrients and passive antibodies available in the calf’s first milk will be reduced.

Studies have shown that lower-quality colostrum can make a calf three-and-a-half times more likely to get bovine respiratory disease (BRD).

Add to this the nutritional challenge and lower weaning weight common in drought-year calves, plus the environmental effect of summer heat, and you significantly reduce the immune response of a cow and calf.

With a lower level of protection, the calf will be more susceptible to disease beyond weaning and into the feedlot phase. If the calf is born with a mineral deficiency, any environmental stress will immediately begin to play a role in its ability to respond to disease.

In short, the calf has been stressed from conception to weaning and the cow for two years in row. If drought conditions continue, as it has in many places, each cow-calf generation will see less consistent feedstock and need closer monitoring to avoid malnutrition.

Next steps for a producer

Cattle moved from a sale barn to a feedlot or backgrounding operation are more likely to suffer from BRD wrecks. Cattle with similar origins exhibit similar warning signs.

For instance, cattle coming from parts of Texas have faced severe drought conditions the past several years and don’t respond well to treatment for diseases. It isn’t the type of products being used as much as the fact that cattle lack the ability to respond and adapt to stressful events because their systems are compromised as a result of the drought.

With regard to calves, once they get to their destination, it’s expected they will be healthy, and so they are handled that way. Consequently, many producers miss the early warning signs. Outbreaks happen quicker than expected, and cattle are pulled for treatment too late.

Even if cattle are pulled in time, these nutritionally challenged cattle may be unable to respond because their immune systems lack the basic building blocks to function.

The question to be answered is: How do we stop these cycles? There are no metrics that can be measured, but anecdotally we are putting the pieces together.

Producers need to manage all cattle as “high risk” when dealing with calves coming out of a drought and do everything possible to reduce stress. This can be as simple as how cattle are handled, moved and treated.

Another important aspect to focus on is nutrition. Poor nutrition, in addition to drought stress, will only deplete reserves quicker. Look at replacing what nutrients have been lost beginning with the fetus, and review your feeding program with your veterinarian and nutritionist.

You can’t manage what you don’t measure. You will have better luck utilizing diagnostics to determine the situation, which is especially true when looking at disease outbreaks in our herds.

Every sick calf should be recorded and all feedstuffs should be documented so producers can use the information to determine triggers and begin pulling deeper.

A sound vaccination program and having a good eye for cattle are also important. Can you pick up an outbreak and get ahead of it before it happens? Be diligent about monitoring the clinical signs and pull cattle quicker since you know they don’t have the necessary resources to respond independently.

We know we are at the mercy of Mother Nature every year. We face blizzards, mud and dust, but we don’t often think past the quality of our forages when we discuss drought. We must incorporate the best management practices available to mitigate the long-term effects. And remember, cattle are not the same every year, and we cannot treat them as such.  end mark

eric moore

Eric Moore

Technical Services Manager
Merck Animal Health