By Dr. Casey McMurphy - Red Angus World Resources Editor
Just in time for weaning comes, 40 degree temperature swings and the risk for bovine respiratory disease complex (BRD). This disease complex is the number one economic loss to the beef industry each year. As cattle producers, we know what this does to our bottom line and these are typically the visible costs associated with BRD. It is estimated that BRD costs the beef industry $800 to $900 million annually due to reduced feed conversions, treatment costs and death (Chirase and Green, 2001).
Loneragen et al. (2001) concluded that there are approximately 7.2 deaths per 1,000 head or about 1% death loss due to BRD. This may seem insignificant, but when cattle are worth what they are today this becomes very important and is the reason for so many products in the marketplace to prevent and treat BRD. As we go into weaning season we have lots of choices when it comes to preventing and treating BRD. Attached is a guide of the primary antibiotics that are out there to treat and or control bovine respiratory disease. Unfortunately there are no silver bullets out there for BRD. There are great products that can help reduce or eliminate mortality at your facility, depending on the risk level and value of your cattle.
With regards to antibiotics, this article will focus on the control of BRD. If we look at the available antibiotics to combat BRD we must look at the class of molecules that these antibiotics fall into. First, there are dose dependent antibiotics and time dependent antibiotics. In both instances the goal of an antibiotic is to be at a level above the minimum inhibitory concentration (MIC 95) for a given bacteria associated with BRD, i.e. Mannheimia haemolytica. This means that at a given antibiotic concentration, 95 percent of the bacteria were inhibited at this level in a laboratory setting.
With that in mind, time dependent antibiotics that get into the lungs and use the animal’s immune system to combat bacteria are primarily in the antibiotic class called macrolides. The most commonly used antibiotics are Micotil, Draxxin, Zactran and now Zuprevo. All of these antibiotics are labeled for the control of BRD and can therefore be used metaphylactically. Metaphylaxis is the the timely mass medication of a group of animals to eliminate or minimize an e x pected outbreak of disease. This process is primarily used in the feedlot to prevent future illness rather than at the producer level, however with the price of cattle and or the value of seedstock and the environmental stress cattle went through this summer it might be an option that producers look into.
Assuming you save one potential herdsire, $5,000 plus, with pre-treatment you will pay for the mass medication of 250 head of 650 lb weaned calves at $20/head antibiotic cost. This doesn’t even account for the calves that have subclinical BRD and you never even gave an antibiotic. Research demonstrated that a high percentage of cattle never diagnosed with BRD still had lung lesions at harvest (68%) (Wittum et al., 1996). These researchers determined that these animals with lung lesions that were never diagnosed with BRD had a reduced average daily gain of 0.17 lbs (Wittum et al., 1996).
These are the hidden costs associated with BRD and definitely warrant further investigation from the industry. In closing, metaphylaxis is not a process that should be incorporated into every operation, but in cases where environmental stressors cannot be avoided there are options to help with BRD. Additionally, it seems like an expensive practice as well, but if put in perspective with the value of cattle it can actually be a very economical practice that improves your bottom line.
May all your efforts be rewarded!
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Antibiotic Resource Guide
Chirase, N. K. and L. W. Greene. 2001. Dietary zinc and manganese sources administered from the fetal stage onwards affect immune response of transit stressed and virus infected offspring steer calves. Animal Feed Sciences and Technology. 93: 217-228.
Loneragan, G. H., D. A. Dargatz, P. S. Morley and M. A. Smith. 2001. Trends in mortality ratios among ccattle in US feedlots. J. Am. Vet Med. Assoc. 219: 1122-112.7
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Wittum, T.E., N.E. Woollen, L.J. Perino and E.T. Littledike. 1996. Relationships among treatment for respiratory tract disease, pulmonary lesions evident at slaughter, and rate of weight gain in feedlot cattle. J. Am. Vet. Med. Assoc. 209: 814-818.
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