There is much we don’t yet understand about the risk factors that lead to summer pneumonia in nursing calves. In fact, there is a study currently underway to explore the root causes of summer pneumonia as there is still much to learn about this disease.

READ: Researchers mobilize to whip summer pneumonia in calves 

In my second installment of my Summer Herd Health series, I look at five risk factors that can increase the chances of a calf getting pneumonia. These include:

1. Calving management

Adequate and immediate intake of colostrum after a calf is born is critical for avoiding summer pneumonia in nursing calves, as well as other health problems down the road. So if a calf gets a rocky start, health issues may plague that calf throughout its lifetime.

In a recent newsletter, Rachel Endecott, Montana State University (MSU) Extension beef cattle specialist, explains, “Briefly, the immunity a calf receives through colostrum is called passive immunity, and is the major source of immune function in the newborn. If calves receive only limited amounts of colostrum, this is termed failure of passive immunity. Calves that experience failure of passive immunity are twice as likely to get sick before weaning, and five times more likely to die before weaning than calves that have adequate passive immunity. This means that incidence of summer pneumonia could be influenced by management at calving, by breeding decisions the previous summer that may have resulted in calving difficulty (limiting the calf’s ability to get up and nurse quickly after birth), or by poor nutrition management or other stresses on the cow during gestation.”

Did you miss part one in the Summer Herd Health series? Check it out here: Symptoms of nutrient deficiencies; PLUS: 5 mineral supplementation tips

2. Commingling & long-distance travel to summer pastures

“Commingling is a major and well-known risk factor for the development of bovine respiratory disease in calves after weaning,” Endecott says. “While mixing sets of cattle is not normally a chief risk for nursing calves, commingling of groups from the same operation during the grazing season should not be ignored in regard to summer pneumonia risk. Moving pairs long distances to new pasture may also play a role.”

3. Weather

“The weather can be a risk factor both early in the year and during the peak summer pneumonia season,” says Endecott. “Certainly, inclement weather can play a role in the success of passive transfer of antibodies from dam to calf. Heat stress, cold stress, and unexpected preweaning precipitation events like snow or freezing rain can all cause weather stress than can contribute to summer pneumonia.”

4. Cow nutrition

Endecott adds, “Nutrition stress on cows during gestation can negatively impact calf health throughout the life of the offspring. Both energy and protein have been found to have impacts on fetal growth and development in utero and post birth. Furthermore, poor nutrition can negatively impact colostrum quantity and quality. Nutritional impacts of a change in diet can also impact nursing calves directly. Examples might include change to a lush pasture, change to pasture quality during drought, or creep feeding. Certainly, trace mineral deficiency, especially copper, selenium, and zinc, can negatively affect the immune system, which may result in increased susceptibility to summer pneumonia. In addition, toxicity from minerals, such as high-sulfate water, may impact calf health as well.”

5. Exposure to pathogens

“Exposure to pathogens such as IBR (infectious bovine rhinotracheitis), BVDV (bovine viral diarrhea virus), BRSV (bovine respiratory syncytial virus), BRCV (bovine respiratory coronaviruses), and Mycoplasma bovis, either within the herd or from other populations, is also a risk factor in summer pneumonia,” she adds.

Knowing the causes might influence some managerial decisions we make to avoid summer pneumonia, and although it’s sometimes a pain to corral a calf for treatment when they are out on summer pastures, fortunately calves suffering from pneumonia often respond well to treatment. For symptoms and treatment options, check out “Recognition and treatment of bovine respiratory disease complex,” by John F. Currin and W. Dee Whittier, Extension specialists and professors at Virginia-Maryland Regional College of Veterinary Medicine.

How do you tackle summer pneumonia on your operation? Share your strategies in the comments section below.

The opinions of Amanda Radke are not necessarily those of beefmagazine.com or Penton Agriculture.

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