Antibiotics and Bovine Respiratory Disease
Bovine respiratory disease, the most common and costly disease in the beef industry, results from complex interactions between the host, the environment, and potential pathogens. Environmental stressors play a major role in susceptibility to and transmission of disease pathogens. This module describes cost-effective preventive management measures that reduce incidence of the disease and thus the need for antimicrobial treatment. Beef practitioners play an important role in promoting these preventive measures and reducing the unnecessary use of antibiotics.
This module aims to describe a preventive approach to the management of bovine respiratory disease, as well as the judicious use of antibiotics in treating this disease. By the end of this module, you will be able to:
- demonstrate understanding of how preconditioning and other preventive management procedures can reduce the frequency of antibiotic treatments for Bovine Respiratory Disease (BRD).
- describe the components of a good preconditioning program and how BRD can be prevented in the feedlot.
- describe how preventing BRD tends to cost less than clinical treatments with antibiotics.
Bovine Respiratory Disease: Cow-Calf Operation
Bovine Respiratory Disease: Cow-Calf Operation
The Veterinary Office
Louis Anderson, DVM, specializing in food animal veterinary medicine, answers the telephone. Pat Johnson, a cow-calf producer, is requesting assistance with her cattle. Dr. Anderson tells Pat he is on his way.
The Johnson Place
The Johnson farm is a small cow-calf operation. Pat Johnson has a mix of about 85 crossbred and purebred cows. The cows usually calve in April and May with some stragglers calving in June. Pat usually sells her calves in the fall to one of two nearby feedlots, but now the feedlots are reluctant to give her a good price for her calves. They claim that too many of them get bovine respiratory disease (BRD) once they get to the feedlot. This requires antibiotic treatment, and the cattle frequently do not gain weight as fast or efficiently as those that stay healthy. Having just read in the Farmers Daily Journal that BRD ("shipping fever") is caused by bacteria, Pat wants a prescription for the latest antibiotic to treat all her feeder calves before she sells them to the feedlot.
Pat says, “The feedlot says that about a third of my cattle need antibiotics for BRD once they get to the feedlot. When they treat a cow for BRD, the antibiotic only costs them about $31. If I treat them with antibiotics before they go to the feedlot, maybe I can prevent this BRD.”
Let’s dispel some of Pat’s misconceptions. The cost of medicines is only a fraction of the costs incurred when an animal gets BRD. One of the best and biggest studies was done in Texas, where they found that about 26% of cattle get BRD while at feedlots. The cost of the medication to treat sick animals was estimated at about $31 per animal. Other costs associated with BRD include increased death loss, increased feed cost per weight gained, and a lower-quality grade (more carcasses grading as "standard" and "select" rather than as "choice") compared to healthy cattle. All these costs added together showed that healthy steers had a $93 more favorable economic return compared to steers with BRD that required antibiotic treatment.
For more information, go to Value Added Calves by John W. McNeill, Extension Animal Science, Texas A&M University.
In addition, antibiotic treatments become ineffective if the organisms the antibiotics are supposed to kill become resistant to them. With increasing antibiotic resistance, it will eventually be necessary to switch to other, usually more expensive antibiotics, thereby increasing the direct costs for the feedlot.
Bovine Respiratory Disease Prevention
Dr. Anderson says, "BRD is a big problem in feedlots. Once cattle show signs of disease, much of the damage has already been done. It is better to prevent disease than to use antibiotics to cure animals after they are already sick. To move from treatment to prevention, we need to understand the many causes of BRD. There are many known viral and bacterial agents, but various types of stress also contribute."
What Is Preconditioning?
Preconditioning of calves is the management of calves at the cow-calf operations before shipping them to the backgrounder or directly to the feedlot. An effective preconditioning program during the four weeks before shipping should result in lower morbidity and mortality at the feedlot.
|“BRD, or shipping fever as many call it, is caused by bacteria—that’s why I want to use antibiotics.”|
|“Yes, but they are ubiquitous opportunistic bacteria (2) that are present on almost all farms. This means that they are normally present in low numbers where they wait for an opportunity to overgrow their neighbors and invade the living tissue. Without an opportunity, they typically cause few problems. Factors that create an opportunity include stress (3), improper housing, and viral infections. So if we can control these disease precursors, we can reduce the risk of BRD. You need to ensure good colostrum to newborn calves, maintain a comprehensive vaccination program and follow other good husbandry practices including a good biosecurity program.”|
What Is a Backgrounder?
The backgrounder is a person who provides management services that many cow-calf producers omit, such as castrating, dehorning, and vaccinating. Backgrounders also consolidate calves from many different small producers, get them ready for feedlot, and merchandize them to feeders who demand a more uniform group of calves to put on feed.
Now it's time to Check Your Understanding of Beef Cattle 1.
Healthy cattle normally carry many bacterial and viral agents in their respiratory system. When stressed, their immune defenses are overwhelmed and BRD develops. Controlling these stresses is often the most cost-effective way to reduce disease, since stress and other disease precursors make the animal more susceptible to BRD. Many viral agents only produce mild clinical signs by themselves but can predispose the animal to bacterial infections when combined with stress. A good preconditioning program can help reduce the need for antibiotic treatment of BRD at the feedlot.
A Preconditioning Program
The risk of calves developing BRD when moved from a cow-calf operation will be reduced if the following preconditioning steps are followed.
- Vaccinate against the major viruses and bacteria that cause bovine respiratory disease at least two weeks before weaning, and boost at least two weeks before shipping. Vaccines should include those against infectious bovine rhinotracheitis, bovine respiratory syncytial virus, parainfluenza 3, bovine viral diarrhea virus, Histophilus somni, and Mannheimia haemolytica.
- Feed a well-balanced ration, including correct proportions of vitamins and minerals, and ensure that calves are eating from a bunk and drinking water from a trough at least 30 days before shipping.
- Wean calves at least 30 days before shipping.
- Castrate and dehorn calves at least 30 days before shipping.
- Prophylactically treat calves with an anthelmintic for internal parasites and, if needed, treat with pesticides for external parasites at least 14 days before shipping.
|“So, what you are saying is that the best thing to do for these calves is to precondition them, instead of giving them antibiotics, before they go to the feedlot?”|
|“That’s correct, Pat. And the best news is that the feedlots may be willing to pay a premium. Because we have increased the chance of them staying healthy, we have also increased the chance of the calf performing optimally and increased the chance of producing a quality product. Producers can see up to a $3−$4 premium per 100 pounds of preconditioned animal weight at auction or sale compared with nonpreconditioned calves. Plus, since animals are more likely to remain healthy, we have reduced the likelihood that antibiotics will be needed for these animals, and therefore we have reduced the changes of antimicrobial resistance developing.”|
|“Wow, I never thought of it that way. I guess it's time for me to start preventing BRD.”|
Management procedures included in a good preconditioning program can help prevent BRD. This tends to be more cost-effective than antibiotic treatment of cattle that develop BRD. Additionally, the overuse of antibiotics will eventually foster antimicrobial resistance, which can negatively impact both animal and human health.
Now it's time to Check Your Understanding of Beef Cattle 2.
BRD: Feedlot Operation, Diagnosis, and Treatment
Dr. Anderson's next call was to one of the feedlots that was purchasing Pat's calves, which were developing BRD at the feedlot. Bill, the feedlot manager, asked Dr. Anderson to come down because the cattle had been having more problems lately with BRD.
Last year, Doc computed BRD rates by farm of origin and helped Bill identify farms that had high rates of BRD. He determined that most of those farms with high rates of BRD had not been preconditioning their cattle. To encourage preconditioning of calves, Bill's feedlot began paying more for preconditioned calves (and less for calves that were not preconditioned).
Once calves arrive at the feedlot, Bill's approach for controlling BRD is to carefully observe the cattle for coughing and then give the coughing cattle a couple of antibiotic injections. Bill suspected that the antibiotic didn't cure whatever was causing the coughing, but he felt maybe it gave sick cattle a boost in fighting off the infection.
|“OK, let’s talk about diagnosis of sick cattle. You want to detect sick cattle as soon as possible. This will require you to spend some time each day carefully observing the cattle."|
Early recognition of cattle with bovine respiratory disease: Look and listen for a soft repetitive cough, watery dull eyes, and a clear nasal discharge. Sometimes affected cattle rapidly lick their nostrils, yet they appear to have a dirty nose. The membranes around the eyes and nostrils may be reddened. Sick cattle will also decrease the amount they eat and not be as aggressive at the bunk. Observe any cattle hanging behind the bunk after the feed wagon goes by or at the bunk without feed on their nose. Sick cattle may show hanging heads, a gaunt appearance, and hollow paralumbar fossa.
|“Next, we need to develop a specified treatment protocol for making decisions regarding which cattle to treat and what therapies to use. By having a treatment protocol, we can avoid incorrect treatments and achieve some consistency that enables us to evaluate trends in treatment success and failures. We need a protocol for each common problem or disease process. Keep in mind that you must look at the animal as a whole, observing clinical signs, days on feed, number of previous treatments, and body temperature. Here is an example of a treatment protocol for shipping fever based on body temperature."|
Example of a Treatment Protocol for Shipping Fever Based on Body temperature
"We should also develop treatment protocols for other common feedlot problems such as foot rot, acidosis, bloat, and neurological diseases. It is important to frequently evaluate these treatment protocols to see if they have been successful. Our goal for first-line therapy is to achieve an 80% success rate. The end goal is to achieve a good response in treating diseases while at the same time using antibiotics prudently.
"Having said all that, treating disease is expensive. Once clinical signs appear, you have already lost lots of the animal's productivity. Also, treatment is not 100% effective. Cattle affected by BRD will never be quite as productive as cattle that were never affected. So the best way to handle BRD is to prevent it!"
|“What are the most important ways to prevent BRD so I won’t have so many sick cattle to treat?”|
|"You can start by thinking about the factors that may contribute to BRD. Contributing factors include heat, cold, dust, dampness, dehydration, hunger, anxiety, nutritional deficiencies, transportation, and commingling of cattle from different sources. Some of these contributory factors can be eliminated with some farm management changes that involve relatively small financial investments. Some people spend a fortune to have the diagnostic laboratory identify all the infectious agents, but many of these agents are present even in herds with low rates of BRD. Most of the infectious agents are opportunists, meaning that they cause disease only if given an opportunity, such as when cattle are stressed in some way. Focusing on the reduction of stressors can be a very cost-effective approach."|
Summary of Good Management Practices for Preventing BRD (Cow-Calf and Feedlot)
Before shipping calves from the cow-calf operation (or other source of cattle) to the feedlot:
- Feed a well-balanced ration, including correct proportions of vitamins and minerals, and ensure that calves are eating from a bunk and drinking water from a trough at least 30 days before shipping
- Wean calves at least 30 days before shipping
- Castrate and dehorn calves at least 30 days before shipping
- Prophylactically treat calves for internal and external parasites at least 14 days before shipping
- Minimize transportation time from cow-calf operation (or other source of cattle) to feedlot
- Make sure shippers provide adequate rest periods for the cattle during shipping with access to water and food
- Discourage use of hot shot or electric prod, yelling, and aggressive handling
- Keep cattle in groups based on their herd of origin
- Do not introduce new animals into the group if possible
- Newly arrived cattle should be isolated as much as possible for 2−3 weeks upon arrival
- Slowly introduce cattle to high-energy rations and make sure vitamins and minerals are adequate
- Make sure newly arrived cattle have feed and fresh, clean water close by
- Don't overcrowd cattle
- Control dust and mud
- Make sure facilities are well ventilated
|"What about vaccinations? I give vaccinations as soon as the calves arrive at the feedlot."|
|"Unfortunately, vaccination for BRD upon arrival at the feedlot is not the best answer. Vaccines do not result in immediate protection. It can take several days, even weeks for the immune system to develop a protective response against BRD pathogens. By the time cattle respond to the vaccine given upon arrival at the feedlot, they typically have already been stressed and thereby put at high risk for developing BRD. Although vaccination at arrival can have some benefit, optimal protection can best be achieved by vaccinating at least two weeks before weaning, with a booster at least two weeks before shipment to the feedlot. That said, vaccination upon arrival is still a good management procedure if vaccine status is unknown."|
Economic Impact Associated with Bovine Respiratory Disease in Beef Cattle
Research has shown that the estimated cost of treating cattle with bovine respiratory disease, from weaning to slaughter, is equal to approximately 7 percent of the total production cost, compared to animals that do not experience bovine respiratory disease. Greater emphasis must be placed on prevention of bovine respiratory disease (Griffin, 1997).
The Cost of Bovine Respiratory Disease
Gross lesions of bovine respiratory disease include lung lesions and lymph nodes that are swollen and enlarged. One study from Oklahoma (1) compared steers without lung lesions to steers with lung lesions and affected lymph nodes. The steers with lung lesions and affected lymph nodes had $74 less net return, of which 21 percent was due to medicine costs and 79 percent due to lower carcass weight and lower quality of meat. Note that this study agrees fairly closely with the Texas study (2) that estimated a $93 less return for each sick animal, with medicine costs amounting to 31 percent of the estimated economic loss.
Now it's time to Check Your Understanding of Beef Cattle 3.
- Investing in the prevention of BRD is important because much of the animal's productivity has already been lost once the clinical signs of BRD appear.
- Preconditioning cattle before their arrival at the feedlot and observing cattle frequently for signs of BRD are management procedures that can help reduce BRD.
- Reducing stress during transport, using biosecurity measures to prevent transmission of pathogens, and providing a clean, comfortable environment can all help in reducing stress while in the feedlot.
- When treatment is necessary, utilizing appropriate protocols regarding which cattle to treat and what therapies to use also aid in the management of BRD. By implementing these preventive measures, the need for and use of antimicrobial agents to treat BRD can be limited.
- Gardner, BA, et al. 1998. Impact of Health on Profitability of Feedlot Steers. In: 1998 Animal Science Research Report. Beef and Dairy Cattle, Swine, Poultry, Sheep, Horses and Animal Products, Oklahoma Agricultural Experiment Station, Division of Agricultural Science and Natural Resources, Oklahoma State University.
- Griffin, D. 1997. Economic Impact Associated with Respiratory Disease in Beef Cattle. Veterinary Clinics of North America: Food Animal Practice. 12(3):367−77.
- McNeill, John W. Extension Animal Science, Texas A&M University. Profits and Carcass Quality.