Beef research profits from debate
This summer’s American Society of Animal Science annual meeting had hundreds of research presentations on every animal subject known to humanity were reported. There was no shortage of controversy over what to feed beef cattle. At times, grass vs. grain controversies sparked heated debates.
It’s hard to escape the hype over what beef-raising system is superior. Arguments run from the effects on beef’s nutritional value for the consumer, to the effects on the world’s environment, to the humane treatment of cattle.
Keep in mind, though, that most cattle feedstuffs aren’t inherently “good” or “bad.” They’re just different.
• Minimum standards may be key to marketing grass-fed beef.
• Heifer beef from concentrates rated better than from forage-feds.
• Supplementing pasture helps pastured beef match feedlot cattle.
Because forages naturally vary more, it’s simply harder to make pasture feeding as consistent as, say, corn feeding. Pasture quality varies enormously. So why is it so surprising that grass-fed beef often lacks uniformity?
A number of grass-fed beef enterprises are on the right track by imposing standard criteria their products must meet. Take, for instance, Kansas-based Tallgrass Beef. It’s promoted by Bill Kurtis, of TV host fame, and is reportedly 100% grass-fed.
Beef carrying the Tallgrass label comes from cattle no more than 30 months of age with carcass weights of 550 to 850 pounds, and a minimum of 1,100 pounds live weight at purchase.
Fat cover must be ultrasound-verified at a minimum of 0.25 inches at a maximum of 50 days before harvest. Actual ribeye area must measure at least 10 square inches.
They must carry a minimum 3.5% intramuscular fat, plus meet a minimum required ribeye shape and tenderness score. Those are reasonable standards that should ensure an acceptable level of product uniformity.
Feed ’em forage or grain?
In an Oklahoma State University study, Angus heifers of similar genetics were split into two groups and finished on either a concentrate-based or forage-based diet. Compared to forage-finished heifers, those finished on concentrates “carcassed” out with:
• Greater adjusted fat thickness (0.73 inches vs. 0.34 inches)
• Higher percentage kidney, pelvic and heart fat (2.14% vs. 1.35%)
• Higher numerical yield grades (3.38 vs. 2.25)
• Higher marbling scores (modest 90 vs. traces 70)
There was no difference between the diets in loin eye area or meat juiciness, as rated by a trained taste panel. And steaks from concentrate-fed heifers had higher tenderness ratings, higher beef flavor intensity, lower grassy/cow-y flavor intensity and higher paint-y/fishy flavor intensity than steaks from forage-fed heifers.
This study is typical of many comparisons of grain- versus forage-fed beef. Grain-fed beef tends to be fatter, more tender and rated higher by taste panel evaluators. To fairly compare the two, however, more details are needed. Just how good and consistent were the forages being fed? Were the concentrate- and forage-fed cattle harvested at similar days on feed? If so, perhaps forage-fed cattle simply needed more time on feed!
Is supplementing pasture worth it?
Maybe, just maybe we can have some of the best of both worlds by supplementing grazing cattle — even with the required extra labor. Iowa State University workers offered byproduct feeds to pastured crossbred yearling steers via self-feeders.
Diet 1 was corn grain/dried distillers grain with solubles. Diet 2 was soy hulls/DDGS. Self-feeders were available while the cattle continually grazed cool-season grasses at about 2.3 animals per acre. Average daily gains were excellent for both, but a bit higher for cattle fed Diet 1 (3.50 pounds vs. 3.34 pounds per day for Diet 2).
Diets didn’t affect dressing percentage, yield grade or quality grade. Ribeye tissue samples were analyzed for lipid fat components that are implicated in human health. Cattle fed Diet 2 did have greater conjugated linoleic acid, or CLA, levels — probably related to the higher fiber and lower starch levels of soy hulls vs. corn grain. But CLA levels of both groups weren’t as high as those typically reported for all-grass-fed beef.
Diet had no effect on total lipid, total saturated fatty acid, polyunsaturated fatty acid or monounsaturated fatty acids. Conclusion: Pasture-reared cattle perform comparably to feedlot cattle in the yard and on the rail when supplemented with byproducts.
Harpster is a Penn State animal scientist and a beef cow-calf producer.
This article published in the October, 2010 edition of AMERICAN AGRICULTURIST.