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Northwest Iowa Dairy Outlooks

A local discussion of current science and issues concerning dairying in northwest iowa

The findings of a recent study conducted by Australian researchers has challenged the long-held belief of the beef industry that flighty cattle are at a higher risk of producing dark, firm and dry meat.

Dark cutting is a complex problem caused by low muscle energy (glycogen) at the time of slaughter. Depletion of glycogen during the pre-slaughter period is controlled by many factors, one of which is the animal’s temperament.

Temperament affects how agitated cattle become and how much adrenaline they release during handling, and therefore, in theory, how much muscle energy they deplete between leaving the farm and slaughter.

The syndrome in beef carcasses produces meat that is dark in color, dry to eat, spoils quickly and has variable tenderness. It affected 3.6 percent of more than 2 million carcasses graded by Meat Standards Australia in the 2011/12 financial year, costing the beef industry millions of dollars.

In their study, the researchers measured the temperament of 648 commercial lot fed cattle using flight speed, an electronic measure of how quickly an animal exits a weighing chute. Flightier animals will exit at a faster speed while quiet animals move more slowly.

Their results showed that as flight speed increased, muscle glycogen concentration in the loin muscle at the time of slaughter also increased, indicating that the cattle that had higher flight speeds were at a lower risk of producing dark cutting carcasses in this study.

Only 2 percent of the cattle in the study were graded as dark cutters (pH greater than 5.7 and/or meat color score of 4 or higher) and those carcasses were evenly distributed across the range of flights speeds measured.

Calmer cattle have been shown to have higher growth rates and more tender meat than flighty animals. These positive benefits have been shown in many different studies around the world.

Producers need to continue to cull flighty cattle and minimize variation in temperament across a herd but also to habituate their quiet cattle to change according to the researchers.

In addditon, producers and processors also need to ensure that calm cattle are treated with as much care during the pre-slaughter period as their more reactive counterparts.

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