According to the Renewable Fuels Association, the ethanol industry in the United States produced an estimated 40 million metric tons of distillers grains (wet, dried, and modified) in 2015, of which 32 percent were used on dairy farms. Distillers grains are a source of energy and nonrumen degradable protein for dairy cattle diets and are generally an appealing ingredient for Midwest dairy farmers because of the lower price and availability in the market compared to other feedstuffs. However, nutrient content variability (inconsistency) of the product within and among plants is frequently mentioned as a constraint by dairy producers and nutrition consultants.
In a survey conducted among local dairy producers by the Dairy Science Department at South Dakota State University in 2011, dairy producers were asked the degree of importance of several distillers grains issues (1 = none; 2 = low; 3 = average; and 4 = high). “Variability between batches” was the issue with the highest degree of importance (3.8), followed by protein content (3.5), and fat content (3.4).
Similarly, results from another survey published by the National Agricultural Statistics Service in 2007 showed that consistency was a concern to dairy producers. On a scale of 1 to 4 (similar to the aforementioned study), the average was 3.8 for consistent protein, 3.6 for consistent moisture and fat, and 3.5 for consistent fiber.
Looking for a standard
Three university studies have reported the nutrient composition of a large number of distillers dried grains with solubles (DDGS; see table). University of Minnesota researchers (2002) evaluated the nutrient content and variability of 118 DDGS samples from 10 ethanol plants located in Minnesota and South Dakota. Average protein content and fat content values were 30.2 and 10.9 percent, respectively, with coefficients of variation of 6.4 and 7.8 percent.
Continue reading this article published in Hoard’s Dairyman.
