The seasonality in beef grades has been well documented for many years. Early fall presents its own set of problems in beef grading, specifically a higher percentage of the cattle grading B4. These B4 cattle are commonly called dark cutters, as the muscle tissue does not “bloom” or brighten to a cherry red after exposure to air.
In 2007, the prevalence of B4 grades on cattle during August and September reached 2.6 per cent of the youthful kill, which was a historical high. This year, the prevalence is 1.99 per cent and those cattle grading dark are primarily heifers.
Dark cutters are costly to the industry and the plant. The discount on a B4 carcass can reach $50 cwt and the cattle owner must absorb the loss. On the shelf, the meat is less attractive and also cooks differently, having a tendency to dry out. A dark cutter can be a carcass from an animal of any age and includes the high end quality and yield grade cattle. If the meat is dark red to blackish, the quality and the yield of the cattle are nullified and the grade stamp is B4.
There are differences between packing plants, too. A Kansas State University study on grading found some plants have five times as many dark cutters than others. At the time of writing, there are a significantly higher percentage of cattle grading dark at one Alberta plant compared to the other.
Why? Without a change in the way the cattle are handled at the plant, there is little reason to think that it is a plant management issue. Rather, the differences in grading raises questions about whether grading is an objective or subjective process. What is your definition of the colour red? What is bright red to one person may be dark red to the other. So red becomes a subjective colour. Certainly there is standardization but it remains an individual call.
Grading in this country is done by the Canadian Beef Grading Agency, which employs standards set by the federal government. Some have suggested rotating graders between plants would be a logical way to address concerns about the high incidence of dark cutters in one plant compared to the next. To date, the Canadian Beef Grading Agency has not been favourable to this. And so one part of a managerial solution for dark cutters remains very much a secret.
There are a variety of factors that can contribute to dark cutters. Research has proven that certain implant routines are contributors in males and females. The timing on the sale of heifers that have been fed MGA is very important, as is the timing in regards to weather. Extreme hot weather is a factor, but so is fluctuation in the temperature. A study from Colorado State University indicates that a temperature fluctuation in the 24 hours before harvest of 5.6 C or greater (between the daily high and daily low) increased the incidence of dark cutters, especially in heifers. This would explain some of the issues with the September grades. The issue of an increase in the August slaughter remains a mystery.
This year, muddy pens may have been a factor as those conditions can stress cattle. Any stress is a potential contributor and any management style that adds to extreme stress is definitely a factor, such as mixing intact males, a change in feed, or lack of feed and water after long hauls.
It’s an issue that should not be ignored: There are more discounted youthful cattle that grade B4 than there are youthful cattle that grade Prime. Dark cutters are a huge economic issue for the cattle-feeding and beef-processing industry.
We will remain in the dark until instrument grading eliminates the potential for subjective judging of the colour red, and we find prescriptive management solutions. In the meantime, research continues to look at all the factors that contribute to a B4 in Canada, including genetic disposition of the cattle, the effect of rapid cooling of the carcass, and whether carcass pH can be used to distinguish dark-cutting carcasses from those that are simply slow blooming.