Update on Beta Agonist Research

Dan Frese, DVM

One of the hotter topics of discussion in the cattle industry in 2013 has centered around a class of feed additives called Beta Adrenergic Agonists (βAA). There are two FDA approved drugs, Optaflexx® and Zilmax®, in this class that are fed to improve weight gain, feed efficiency and carcass weight during the last 20-42 days of the feeding period. These drugs produce these results by changing cell metabolism, especially muscle cells, to increase protein production/reduce protein breakdown.

The Beef Cattle Institute has conducted research projects as well as case studies during the past year that have focused on industry concerns regarding these feed additives. We have found when we look at blood parameters and clinical signs observed in these studies we were seeing similarities to what has been termed “Fatigued Pig Syndrome” in market weight hogs. Fatigued Pig Syndrome has been attributed to increased stress from events such as handling, sorting, transportation, etc. immediately preceding slaughter. This increased stress load led to a metabolic breakdown in a small portion of the pigs sent to slaughter. The similarity in presentation of adverse events between cattle and pigs in blood parameters and clinical signs has received our attention and focused our thoughts on looking at how we are managing cattle during the last 30 days of the feeding period. Are we seeing “Fatigued Cattle Syndrome”?

Many factors that influence stress levels in our market weight cattle during the last 30 days can be managed to some degree. Factors such as sorting, penning cattle close to loading chutes, animal handling training of personnel, time of day that loading occurs during heat events are just some of the factors that can potentially reduce adverse events during this time frame… both for the feeder and the packer. Management programs aimed at stress reduction during this time period have been quite successful in the pig industry.

So what does all this have to do with beta agonists you ask? The science is not clear as to what the role βAA may play in the loss risk of the late feeding period. However, what is clear, at least to me, is that we have the ability to make a positive impact on our cattle by looking at how we manage and handle these cattle during the final stage of the finishing period.

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