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In the fight against bovine respiratory disease (BRD), beef producers and veterinarians have begun to add adjuvant treatments to antibacterial treatments, but this may be a waste of effort.
A recent study by animal scientist Blake Wilson and others at Oklahoma State University showed that in feedlots, adding adjuvant or secondary treatment to basic BRD antibacterial treatment did not significantly improve health. This is a rare study of a large number of cattle.
Generally, these adjuvant therapies have been divided into three categories according to their intended purpose. They have been classified in several scientific papers.
Category 1. Use corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs) to alleviate the harmful effects of inflammation.
Category 2. Use antihistamines to block histamine activity, thereby blocking inflammation.
Category 3: Through the use of vitamins, minerals, direct feeding of microorganisms (DFM) and vaccines, the immune system is strengthened to help defend against infectious pathogens.
The chart attached to this story from the 2011 NAHMS Feeding Farm Survey shows the most common adjuvant treatments at the time and their frequency of use.
Blake Wilson, Oregon State University's 2011 NZHMS Feeding Farm Survey revealed this list of favorite BRD adjuvant treatments.
The 2011 NZHMS Feeding Farm Survey revealed this list of favorite BRD adjuvant treatments.
Wilson and others wanted to test some of these therapies because they could not find data on their efficacy. They chose the three most commonly used adjuvant therapies at the time, including non-steroidal anti-inflammatory drugs, antiviral vaccines and vitamin C.
They used 516 bulls and bulls with an average weight of 475 pounds, purchased them from various auction markets in Oklahoma within a week, and transported them to the feedlot on average for just over 80 miles. Mix the calves into the receiving fence, freely choose to obtain grassland hay and water, and rest for 24 to 48 hours before the initial processing.
The initial treatment includes a combination of IBR, BVDV types 1 and 2, PI3, and BRSV; a polyclostridium, including Clostridium, Clostridium septicum, Clostridium neo, Clostridium, and Clostridium perfringens types C and D ; And the famous brand ivermectin, used for internal and external parasites. They also recorded the body weight, castrated 355 bull calves, and cut horns on 57 calves.
The calves are visually monitored by trained evaluators, and clinical severity scores are given in the improved DART system, which includes scores for depression, abnormal appetite, and respiratory symptoms. Second, they use rectal temperature to determine eligibility for treatment.
They pulled all calves with a score of 1 (which is a mild clinical symptom of BRD) to calves with a score of 4 (they marked as dying). Then assign one of two options to these calves to receive antibacterial treatment:
All of them received first or second scores and temperatures of 104 degrees or higher.
Regardless of the temperature, all of these have more severe clinical symptoms No. 3 or 4.
All calves that scored No. 1 or No. 2 and did not have a fever returned to their pens without treatment.
During the entire experiment, there were a total of 320 animals, and there were 80 animals in each of the four experimental adjuvant treatments. Calves treated with anti-BRD antibiotics are randomly assigned to one of the following four categories:
They found that any of the three popular adjuvant treatments had negligible performance differences during acceptance or completion.
However, in those calves that received only antimicrobial therapy and no adjuvant therapy (control calves), they noticed some statistically effective improvements. These include:
This indicates that calves receiving only antimicrobial agents perform better, which may have important additional effects.
Wilson explained: "I believe these are extremely high-risk calves, they are suffering from a strong natural immune attack (the first treatment incidence rate is 66.5%, the mortality rate due to BRD is 13.2%). Help in the diagnostic laboratory Next, we found Haemolytic Mannheimia, Bovis Mycoplasma, Pasteurella multocida, Bovine Viral Diarrhea Virus and Bovine Coronavirus in three calves randomly sent for autopsy.
"I feel that by using adjuvant therapies other than antibacterial drugs in such situations, we require calves to respond to additional stimuli when the calf system is overloaded, just to cope with immune challenges and survive. We may make the calves survive. The cow is overloaded with the system, so to speak."
"The calf group that did not receive adjuvant therapy improved in numbers, the interval between antibiotic treatments was longer, and the number of deaths was fewer. However, we ended up conducting more non-trials in the unadjuvanted therapy group , So the total number of animals that died or were removed is almost the same. I believe that additional stimulation from adjuvant therapy may cause these extremely high-risk calves to perform worse, have more severe clinical scores, retreat earlier, and eventually die earlier instead of becoming Chronic disease." "At least there seems to be no reason to use any of the three adjuvant therapies tested in this experiment."
In the end, the researchers concluded that adjuvant therapy is likely to be unnecessary expense and does not have any benefit to the calf's health or performance.
The full journal article on this research can be read in the "Journal of Animal Science" at the following URL:
Will NSAIDs help BRD treatment?
In a literature review, Wilson and others pointed out that non-steroidal anti-inflammatory drugs may be beneficial for animal welfare and comfort, or they may not have any benefit, or in some cases they may have a negative effect.
"As you know, the non-steroidal anti-inflammatory drugs we used in our experiments, such as flunixin meglumine, have been shown to reduce inflammation and fever in beef cattle," Wilson said.
"I think there are two problems here. First, fever is the body's natural biological response to pathogens/immune attacks. I don't know that fever must be a bad thing in all cases. I don't know if we fully understand the costs and benefits of fever relief. , Just the symptoms, and how this affects the response/immune challenge to pathogens.
"Another issue is how we use these products in practice, and the pharmacological effects of these products. For example, the industry usually uses a dose of flunixin meglumine with antibiotics during BRD treatment. Then, The animal is unlikely to receive another dose of flunixin meglumine before meeting the PTI requirements, and if it does not respond to the initial BRD treatment, it will be pulled out again a few days later. That is, according to the label, flunixin The half-life of octyl meglumine is only 3.14 to 8.12 hours, so we can only relieve calf symptoms for a few hours at most.
"Maybe it is beneficial, maybe it is not. Our research will say it is not. Other options are to re-administer flunixin meglumine every few hours or look for longer-lasting non-steroidal anti-inflammatory drugs."
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