Growth promotants in cattle can impact tenderness, says study

Researcher warns against steroid or beta-agonist use in cattle 
that won’t be slaughtered until they’re 16 months or older

The longer cattle are exposed to steroids and other growth promotants before slaughter, the more likely its beef will pay a penalty in terms of tenderness, said a researcher from the University of Alberta.

Meat scientist Heather Bruce and her team recently conducted a study on the effects of growth promotants on collagen cross-links — the connective tissue or ‘gristle’ of beef cattle. They found the age of the cattle played a key role: Beef from cattle aged 12 to 14 months had much less gristle and was less heat resistant than that of the older, 16- to 20-month-old population which had been exposed to promotants more times.

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“For the cattle industry — and particularly for those producers involved in guaranteed tenderness programs — the take-home message is the effects of steroid or beta-agonist use are not particularly obvious in cattle processed young,” said Bruce.

“So if you are going to use these products, use them in cattle that will be slaughtered when they are young. The effects of these products seem to be more evident in older animals because these animals are more likely to be subject to more than one steroid implant in their lifetimes.”

The study focused on two populations of animals — 12 to 14 months and 16 to 20 months. Both had a subgroup exposed to prolonged steroid and beta-agonist use, and another subgroup that was not.

“That age range is quite indicative of the age of animals that are slaughtered for beef in this country,” said Bruce. “At various times of the year you’ll either get a product from a very young animal or a product from an older animal.”

The growth promotants used in the study were common, commercially available products administered according to manufacturer instructions.

“Nothing special — just off the shelf, everyday production choices producers commonly make,” she said.

The young cattle received one course of steroids while the older cattle received five treatments of steroids. Generally, Canadian cattle do not receive that number of interventions, she said. However, the extreme number of treatments underscored the significance of the findings.

“It’s a worst-case scenario in terms of usage of steroids,” said Bruce. “I’m not sure many producers would use that kind of rigorous intervention schedule. It essentially said that if you’re going to use these products, five is the highest number of treatments you could possibly use.”

The study highlights that even a few months makes a significant difference in tenderness when using promotants.

“Sixteen to 20 months of age isn’t particularly old in the grand scheme of things, but we have found even with that small change in age we still see a significant change in the heat stability of the cross-links,” she said.

“We haven’t seen a significant change in the amount of force required to cut the meat, but we did not test it among consumers so that’s hard to measure. However, there is definitely a measurable change in tenderness and it’s statistically associated with the cross-links.”

The results of the study also speak to the inherent risks of multiple treatments of growth promotants, said Bruce.

“On average, Canadian producers today are aiming for heavier cattle weights. However, we need to be mindful of the production and quality implications of prolonged steroid use. It might be an option to consider one implant rather than multiple treatments in order to maintain superior tenderness.”

Cory Van Groningen, who operates VG Meats, a farm-to-fork operation in Stoney Creek, Ont., said he looks to this type of research to improve the tenderness, flavour and juiciness of the beef he produces. Other researchers have tied steroid use to reduced tenderness, he said, but Bruce’s study is unique in that it specifies the best age in which to achieve peak tenderness while using growth promotants.

“She’s identified the populations where it has the most impact,” he said.

Although Van Groningen does not use growth promotants, he said the study still has value for his operation because it shows a relationship between age and collagen cross-links.

“This research reveals more about the many factors that affect beef tenderness.”

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