“If you can’t explain to the folks at Barnes and Noble in New York City what you do and have them understand and like it, you should not be doing it.”
– Temple Grandin
Exclusive interview with Zilmax researcher Dan Thomson
By Rita Jane Gabbett on 8/29/2013
A lot has happened in the three weeks since the National Cattlemen’s Beef Association met in Denver where spirited discussions ensued about lameness, lethargy and other signs of stress — including occasional sudden death — observed in cattle fed the beta-agonist Zilmax.
At the start of the NCBA conference on Aug. 7, Tyson Foods announced that as of Sept. 6 it would no longer accept cattle fed the growth promotant. By Aug. 16, Zilmax maker Merck Animal Health pulled the additive off the market and laid out plans to study the situation. On Aug. 16, Cargill became the second of the top four beef packers to publically state it would stop accepting cattle fed Zilmax by the end of September.
Industry experts estimate up to 70 percent of the U.S. cattle herd are currently fed one of two beta-agonists: Zilmax or a ractopamine product called Optaflexx, made by Elanco Animal Health. The extra-lean muscle production they stimulate has become a critical component of the beef business model, particularly as cattle herds have shrunk and grain prices have escalated.
If these products were taken off the market permanently, it would wreak havoc on the cost structure for the U.S. cattle industry. To date, what the entire debate lacks is research-based, scientific evidence. To that end, the NCBA and multiple state beef councils funded research started this summer headed by Jones Professor of Production Medicine and Epidemiology at Kansas State University Dan Thomson. Thomson has a doctorate in veterinary medicine and a PhD in ruminant nutrition.
In his first interview on this important research, Thomson spoke to Meatingplacethis week about his research.
Meatingplace: How are you approaching this research?
THOMSON: First we had to do diagnostic workups in the field to identify the gross pathology and clinical signs observed in the cattle involved. Then we make a list of etiologies — it could be a very long list, or it could be very short list in terms of pathogens or syndromes that could be causing different symptoms. Once we have done the diagnostic workup, then we look at the list of possible causes including metabolic disorders, toxins, pathogens or others. It’s not simple. There are many angles to medical and nutritional cases such as this.
Meatingplace: What do you think is causing the symptoms beef packers are observing after the cattle arrive at their plants?
THOMPSON: I think it is a combination of many factors. I think it is a stress-induced situation. That is my intuition — whether it is the size of animals, genetic predisposition, the management of the animal, the length of haul, the beta-agonist dosage or usage, heat stress or all of these things causing stress in these animals which culminates in the observed clinical signs. To add to the many different variables, we can’t identify which animal is going to succumb to it at this point.
I don’t think any of us knows exactly what is going on. There is a lot of speculation in the industry, but to my knowledge we have not dug down into the physiology and the metabolism to better understand the pharmacology, physiology and production management and how all those interface to culminate in clinical signs observed. This is a complex issue with no simple answer.
Meatingplace: Is this showing up more in some cattle breeds than others?
THOMSON: No. Every illness or syndrome like this is an individual animal issue. However, we must manage the problem at a group level because we don’t just put feed in the bunk for one animal. Beta-agonists, and other feed additives, are administered through feed, so the dose of the drug consumed is based on that individual calf’s eating behavior. It is difficult to manage individual animal diseases and problems when you are managing them on the pen level with the delivery of the drug in the feed going to the entire group.
One thing we do know is that it is a small population of cattle that are affected.
Meatingplace: Where are you now in your research process?
THOMSON: We are doing a small intensive physiology study to examine the effects of beta-agonists zilpaterol and ractopamine on finishing cattle. The College of Veterinary Medicine in partnership with the Department of Animal Science at Kansas State University has a research facility where we can monitor individual animal feed intakes, so we can measure how much drug each animal consumes. Besides taking blood samples periodically to measure biochemical markers, we have developed heart monitors that fit cattle to record heart rate and heart rhythms for 24-hour periods.
In the field, we are looking at production management interventions with the use of beta-agonists.
Meatingplace: Which products are you studying specifically?
THOMSON: Zilmax and Optaflexx.
Meatingplace: Are you bringing in cattle that are exhibiting symptoms?
THOMPSON: No. We are using commercial cattle close to slaughter weights and are placing them on diets with or without Optaflexx or with or without Zilmax. Then we put the heart monitors on them and watch their heart rhythms and rates over extended periods of time.
Meatingplace: How long have you been doing this?
THOMSON: We have been doing it for a few weeks and have a couple weeks left on this study and then we will be finishing up.
Meatingplace: How many cattle are you monitoring?
THOMSON: In this study, 30 head. That doesn’t sound like very many, but if you are walking around trying to get the heart rhythms on 30 [large] animals, it is quite a bit to handle.
Meatingplace: What else is involved?
THOMSON: The other study we are conducting is acquiring samples of heart, kidney, liver and lung samples from animals in the field that died suddenly that were either not on a beta-agonist, or were on Optaflexx or were on Zilmax. We are taking samples across the country from cattle feeding facilities and looking at the histology of these samples to see if there is a difference in the pathology of cattle that die while consuming a beta-agonist relative to cattle that die not fed beta-agonists.
Meatingplace: After you finish these trials with the 30 cattle, what happens next?
THOMSON: We will analyze the results, interpret the data and report our findings. People need to understand that this is one of many research projects needed. It will not be the end of knowledge needed to move our technology forward. People have to understand at the end of the day that producers and packers are seeing issues in the field, but we can’t pinpoint yet exactly what is causing the problems. So, we have to continue to work and do due diligence. It is not going to be a quick fix. It is going to take a lot of time and effort. Our consumer expects this of us. With regard to beta-agonists, it is an animal health and well being issue. It is not a food safety issue.
Meatingplace: When do you expect to have some answers?
THOMSON: We’ll have something within the next couple of months. We are going to learn a lot going forward. I think we (the industry) have done the prudent thing. I commend Tyson for having the guts to step out and say we need to investigate this. I commend Merck for their proactive removal of the product until more is learned. I will be serving on an advisory board for them along with the all the animal welfare specialists from several universities, companies and producer groups. Merck is saying let’s step up and work forward on this. I think at the end of the day, we have had some issues reported. We are doing the research in the field and through the literature. The beef industry continues to make me proud for doing the right thing. Now, it is time to do the research that will lead to decreased issues with the cattle in the field.