“Watch the Fat – an Update”
by Chris Reinhardt, feedlot specialist
Since the advent of cattle feeding, we learned early on that cattle make very good use of by-product feeds that monogastrics—pigs, chickens, and people—can use very little of productively, especially if cellulose—fiber—makes up the majority of the feed. The corollary to that guideline is that if cattle have to compete with humans for a feedstock, humans win.
Three decades ago, wheat was a common ingredient in feedlot diets throughout the high plains. Today, the opportunity only occasionally presents itself due to temporary pricing inversions. We like our bread and Twinkies—humans win.
A similar, but more subtle phenomenon has taken place gradually over the past few years, since the ethanol industry boom began. Corn oil is worth more marketed to humans as that—corn oil—than to livestock in the form of distillers’ grains (DG), and the ethanol plants have developed novel technologies to extract an increasing amount of that oil from the by-product.
Early on, the fat content of corn DG was commonly between 11 and 13%; however, today, some corn DG with fat levels near 8%, and some as low as 4%. Fat in cattle feed contains 2.25 times the energy of carbohydrates, so removing fat such that the void left is filled with predominantly cellulose, would be expected to result in a lower energy feed.
As a capitalist, I am in favor of ethanol companies finding a way to increase their revenue from secondary product streams. But as a cattle nutritionist, I must also be aware that removal of oil from DG will dramatically reduce the value of the by-product for cattle feed.
Recent research conducted at the University of Minnesota concluded that for every 1% decrease in fat content of the DG, we should expect nearly 2 Mcal NEg / cwt reduction in energy value. Or, if your DG are 8% fat instead of 12% fat, the NEg for those DG is 65 instead of 73. So if DG makes up 40% of the finishing diet, and fat content of those DG was formerly 12% and is now 8%, we’ve lost 3.2 Mcal NEg in the final diet. We’re feeding a 61 Mcal NEg finishing diet when we used to feed a 64 Mcal NEg diet. That’s a substantial change. If the DG has 4.5% fat, we’re feeding a 58 Mcal NEg finishing diet—a “hot” grower diet really. Low-fat DG has less value for finishing cattle than does high-fat DG.
Fat content is a major reason DG have value in the finishing diet. If the fat percentage in DG has decreased over time, the feed value of DG for a cattle finishing diet is also decreased, and the astute cattle feeder should adjust pricing expectations accordingly.
