Bovine respiratory disease (BRD) is a major cause of death among calves and one of the largest health challenges facing our modern-day dairy industry. We are also experiencing an all-time high cost for replacement heifers — averaging $2,300 or more — and as a result, replacement heifer inventories may struggle to recover in the coming years. Understanding and managing BRD is necessary to raise and keep calves healthy for the sake of your replacement herd.
Vaccines and antibiotics have been the most common methods for preventing and treating BRD, respectively. Still, vaccine effectiveness has not been consistently achieved, and growing concern over antibiotic resistance leaves the door open for alternative prevention and treatment options. Such research is studying the use of essential oils, plant extracts, antioxidants, and probiotics to prevent and treat BRD and improve overall disease management. Nevertheless, consistent work to reduce pathogen load and exposure is a critical part of preventing BRD.
The background on BRD
A 2021 meta-analysis study shows that calves diagnosed with BRD have a higher likelihood of dying or leaving the herd before their first calving. Affected calves and heifers that stay in the herd had lower average daily gain (ADG) and produced less milk during their first lactation.
Incidence of disease in early life is consistently associated with reduced growth, production in the first lactation, and productive life. Research from Jud Heinrich’s laboratory at Penn State University reported that each day of a preweaning disease resulted in a loss of 278 pounds of milk production in the first lactation. This contributes to the estimation that the U.S. loses $1 billion every year due to treatment costs and production loss attributed to BRD.
BRD is a complex illness because multiple factors can play a role in its development. Obvious ones include exposure to a combination of viruses, bacteria, and parasites, while not-so-obvious factors include poor nutrition, genetic susceptibility, suppressed immune system, stress, and sudden weather and temperature shifts.
Detecting the disease before it becomes serious is also challenging. Calves are prey species and naturally try to hide signs of illness. One of the earliest signs to look for in group housing is a calf lagging or isolating itself. In hutches, visual signs can include discharge from the nose and eyes, coughing, a tilted head, reduced appetite, and an unwillingness to stand. In auto feeder systems, milk feeding rate and feed refusals can serve as alarms to calves developing BRD. As symptoms worsen, the disease can ultimately lead to pneumonia and permanent lung damage.
General symptoms of BRD include:
- Fever greater than 104°F
- Watery nasal discharge to a thick, cloudy, pus-filled discharge
- Depression and lethargy
- Lack of appetite
- Cough
- Rapid, shallow breathing
- Unwillingness to move, standing with neck extended
- Droopy ears
- Discharge from the eyes and mouth
By the time these symptoms are noticeable, the calf has likely been sick for a few days. Detecting the first signs of BRD before the pathogens have reached the lungs gives treatment practices a greater chance of working. Still, it’s even better if we can prepare a calf’s immune system and body to fight off the disease independently.
More immunity, less stress
While there are many unknowns with BRD, there are also several known precautions we can take to reduce the risk to our calves. The first of these can start as soon as birth.
A clean, high-quality source of colostrum has tremendous benefits for health, growth, and longevity. Most data suggests the effect colostrum has is because it provides the necessary immunity and nutrients to fight disease. Additionally, colostrum provides antioxidants to reduce oxidative stress, essential nutrients for development, hormones for growth, and fat and lactose critical for early life energy.
It’s recommended that calves receive 10% of their body weight in colostrum within the first few hours of life. As calves grow, their immunity can be boosted further with vaccines, dewormers, and adequate nutrition.
Stress is the underlying issue we face when trying to better our herd’s health and production. The most practical way to approach it is to ask, “What is causing my calves stress?”
In just the first four month of life, a calf undergoes numerous stressful events. Birth, transportation, feed changes, disease challenge, vaccination, weaning, and grouping can all induce stress. Each event can have an impact on feed intake, nutrient absorption, metabolism, and so forth.
As mentioned previously, more researchers are studying supplemental and supportive treatments. Calf studies are measuring the effects of feeding essential oils, plant extracts, antioxidants, and probiotics on factors like boosting ADG, lessening lung damage during BRD, lowering oxidative stress in the body, and providing immune support.
In addition to these supportive treatments, making practical environmental and nutritional improvements should not be overlooked. These include:
- Proper ventilation
- Fewer pen movements
- Low-stress handling
- Clean bedding
- Sanitizing feeding equipment and housing surface areas
- Free access to feed and water
- Clean, high-quality feed, free of mold and dust
- Offering electrolytes before and after stressful events
BRD is hard to pin down. What causes it and how to prevent and treat it changes on a herd-to-herd basis. Having the proper understanding and using practical management is still key. With greater scrutiny on antibiotic use, alternatives to traditional treatments may also be an opportunity to satisfy consumer demands while not compromising animal well-being and production.
OCTOBER 2024 issue:
