US Beef processor Cargill has joined welfare reviews into Zilmax after announcing it too will suspend purchases of cattle fed the growth promoter.

In a statement, Cargill backed Merck animal health, the manufacturers of Zilmax, reassuring that the decision was not one related to food safety.

Following the product’s market release in 2007, Cargilll was the last major company to accept Zilmax fed cattle into its plants, which it did in 2012. This was after studies into the beta-agonist and the effect of the active drug Zilpaterol on cattle.

Initial Zilmax concerns related to beef quality and tenderness. However, Cargill's animal welfare worries are now shared across the industry, including those of cattle welfare expert, Dr Temple Grandin.

Early ponderings around Zilmax-fed cattle limping surfaced at a National Cattlemen’s Beef Association Meeting, held earlier this month.

Cargill commended Merck’s decision to suspend sales until better understanding is achieved adding that growth promoters are important to maximise beef production at a time of herd contraction.

“Zilmax, is a feed supplement approved by the U.S. Food and Drug Administration and given to cattle to improve feed conversion, resulting in more beef from each animal harvested,” the Cargil statement said. “Given a situation where the U.S. cattle herd is at its lowest number since 1952, maximizing the yield from each animal is important.”

Lower inventory numbers are beginning to hit the retail sector which reported record highs of $5.357 per pound for July. This is the second time the record has been broken this year.

Even with light volumes, prices were described as mixed by markets' analyst Ron Plain, agricultural economist at the University of Missouri.

The five area average for liveweight steers came in at 42 cents down on the previous week at $186.60/cwt.

He revealed slaughter statistics show that cow slaughter is 2.1 per cent higher for the first seven months compared to the same period last year.

There have been 76,000 more cows culled so far this year which has offset the 2.1 per cent fewer heifers slaughtered, Mr Plain added.

Similarly, Statistics Canada renewed its cattle figures last week which are at 13.54 million, 20 per cent below the 2005 peak. Here, cow slaughter numbers have also offset heifer retention.

Beef cows stand at just over 3.9 million, where they have plateaued since 2011 after falling from 5.436 million head.