News agencies this week have reported on an article appearing in the online scientific journal Plos one regarding animal health and welfare issues associated with beta agonist feed additives. In response, Merck Animal Health issued a statement on Thursday.

Authors of the Plos one article are veterinarians Guy H. Loneragan, BVSc, Ph.D., Texas Tech University, Daniel U. Thomson, DVM, PhD, Kansas State University and H. Morgan Scott, DVM, PhD, Kansas State University.

The researchers analyzed three datasets: one included information from randomized and controlled clinical trials of the beta agonist ractopamine hydrochloride (Optaflexx), while the other two were observational data on zilpaterol hydrochloride (Zilmax). Analysis of those datasets indicated an association between beta agonist use and increased mortality rates among heavy cattle, particularly during periods of risk for heat stress or cold stress.

In response, Merck Animal Health issued its statement citing results of more than 30 controlled, randomized research trials showing no increase in death loss among cattle fed Zilmax. The company currently is sponsoring an extensive field evaluation program conducted by independent experts.

The Merck statement also points out that the analysis related to Zilmax in the Plos one article was based on observational data, rather than controlled, randomized experiments.

Read the full statement from Merck Animal Health.

Watch for a more detailed update on what’s happening with beta agonists in the April issue of Drovers/CattleNetwork magazine.