"Distillers grains are often a cost-effective addition to feedlot diets, but rumors sometimes say feeding distillers may create problems with beef quality, says Rosie Nold, the Agriculture and Natural Resources program director at South Dakota State University.
What does research say?
The University of Nebraska has done some of the most comprehensive research. Below, Nold summaries the results from studies conducted between 2006 and 2010:
"The most familiar measure of quality to many producers is quality grade and marbling score. Research comparing feedlot diets with 0, 15, or 30% wet distillers grains as a percentage of the diet dry matter found no difference in marbling score. Furthermore, when ribeyes were broken down and analyzed for actual percentage of intramuscular fat, no differences were found. What does this mean? The misconception that there may be more marbling or fat present than can actually be seen by the graders or grading instruments is simply not true. The addition of wet distillers grains to feedlot diets did not decrease marbling score and had no effect on the ability of graders to see the marbling.
"From a consumer perspective, beyond marbling and quality grade there are other measures of beef quality, including color and flavor. Feeding distillers grains can have an impact on these factors, primarily because of the high fat content of distillers grains. Meat from cattle fed higher levels of wet distillers has a higher percentage of polyunsaturated fatty acids (PUFA). As people, our diet recommendations say we should eat a relatively higher percentage of PUFA as compared to saturated fatty acids, so from that standpoint, a higher percentage of PUFA is good. However, from the standpoint of shelf-life of meat, more PUFA can mean negative effects on color and flavor.
"Looking at both ribeye steaks and flat-iron steaks, studies showed both types of steaks had obvious discoloration (brown) earlier during retail display when those steaks originated from cattle that had been fed wet distillers grains. Taste panel evaluations following retail display of steaks also showed more people identified a livery off-flavor in steaks from cattle that had been fed wet distillers. Chemical tests confirmed the presence of compounds associated with rancidity. What exactly does that mean? The steaks turned brown faster, making it less likely that consumers will purchase them, and if consumers did purchase the steaks, they were more likely to notice an off-flavor or rancid taste. Both the color and flavor problems are related to level of PUFAs, and how they react when exposed to oxygen in the air, a process called oxidation, which is associated with rancid flavors. The good news is that the simple step of feeding Vitamin E, which helps prevent or slow oxidation, along with the wet distillers can help reduce these problems."Source: SDSU