March 14, 2014

US study links rising cattle deaths to beta-agonists

A recent US research study which was published in a scientific journal PLOS ONE indicates that the number of cattle deaths linked to beta-agonists may be higher than reported.

Researchers from Texas Tech University and Kansas State University found that more than 3,800 cattle in 10 feedlots that were fed the drug died between 2011 and 2012. The study noted that 40-50% of those deaths were attributed to administration of the drug.

The researchers said that while death is a rare event in feedlot cattle, the data reported provide compelling evidence that mortality is nevertheless increased in response to administration of FDA-approved βAA (β-adrenergic agonists) and represents a heretofore unquantified adverse drug event.

Merck & Co., which makes Zilmax and Elanco Animal Health, which makes ractopamine, criticised the researchers' methodology and noted that the feed additives are approved by the Food and Drug Administration.

Beta-agonists are credited with improving beef production efficiency. Growth promotant drugs such as zilpaterol hydrochloride-based Zilmax can add 24 to 33 pounds of live weight to steers and heifers in their last 20 days of time on feed. But questions about the safety of the drug came to light when Tyson Foods Inc., in August 2013, announced the company would no longer purchase cattle fed with Zilmax on concerns that the drug was causing lameness in some cattle.

The researchers noted in the study that they believe a broad and inclusive dialogue that explores the balance between improved production efficiencies achieved through means such as βAA and resultant adverse effects on the welfare of animals they raise for food is needed. This is particularly warranted for those drugs that are approved solely to improve the efficiencies of production yet offer no offsetting health benefits to the animals to which it is administered. For this dialogue to be sufficiently inclusive, it ought to include a broad collection of stakeholders such as animal scientists, cattle and beef producers, animal health specialists, welfarists, ethologists, and consumers."

The study is co-authored by Guy Loneragan, a professor of food safety and public health at Texas Tech, and Daniel Thomspon and Morgan Scott of Kansas State. The study is titled "Increased Mortality in Groups of Cattle Administered the β-Adrenergic Agonists Ractopamine Hydrochloride and Zilpaterol Hydrochloride".