Effects of Dried Distillers' Grains with Solubles (Wheat‐Based) in Feedlot Cattle Diets on Feces and Manure Composition

Abstract

The use of dried distillers' grains with solubles (DDGS) in feedlot cattle (Bos taurus) diets is increasing as the bio-ethanol industry expands. This study investigated how wheat (Triticum aestivum L.) DDGS-based diets impact feedlot cattle nutrient and volatile fatty acid (VFA) excretion. Feedlot heifers were fed DDGS at 0 (Control) 20, 40, 60% or 60% + Ca (1% limestone) of dietary dry matter. Feces and manure were sampled monthly over a 133-d finishing period. Total nitrogen (TN) (feces only), total phosphorus (TP), pH (manure only), and water soluble NH(4)(+) and P contents in feces and manure were higher with 40 and 60% DDGS diets than with the Control. Significant increases in isobutyric, valeric, and isovaleric VFAs (by far the most odorous in manure) were also observed in the feces with 40 and 60% DDGS diets, although there was no change in the total VFA content with diet. Wheat DDGS manure, with higher N and P contents, should be beneficial to crop production. However, it could potentially increase N and P loading on crop lands after application and contribute to greater NH(3) emission and malodor intensity while manure is in the feedlot pen. Estimated manure N loss while in feedlot pens also increased significantly with dietary DDGS levels. The small (nonsignificant) differences in total and soluble N and P in feces and manure between 20% DDGS and the Control (0% wheat DDGS) suggest that excess nutrient flow to the environment and malodors can be controlled by restricting wheat DDGS to a maximum of 20% in cattle diets.

Greenhouse gas emissions when composting manure from cattle fed wheat dried distillers’ grains with solubles

“…The higher EC and water-extractable NH 4 ? -N in wheat DDGS than Control manure reflects greater N and salt excretion into manure originating from the DDGS diet, a result that is consistent with a previous assessment of manure arising from feedlot cattle in which cattle were fed increasing quantities of wheat DDGS (Hao et al 2009). The high NH 4 ?…”

“…to TN in manure is generally higher with higher protein diets (Canh et al 1998). Decomposition and loss of water, TC and TN while manure was stored in piles or in the pen reduced pH, TC, TN and NO 3 -content in the Control and wheat DDGS manure at the time of composting as compared to when it was collected immediately upon completion of the feeding experiment (Hao et al 2009). This outcome would suggest that considerable NH 3 volatilization and organic matter decomposition occurred during the stockpiling period as well as the 45 days that the manure was stored in the feedlot pen prior to initiation of composting.…”

“…This has led to increased availability and use of dried distillers' grains with solubles (DDGS) as a livestock feed (Berger and Good 2007;Klopfenstein et al 2007). With the nitrogen content in DDGS approximately two to three times that of unprocessed grain (Spiehs et al 2002;Widyaratne and Zijlstra 2007), adding DDGS to livestock diets could potentially change the manure pH, N form and content, and C/N ratio, given that these properties are influenced by diet (Hao et al 2005b;Velthof et al 2005;Yan et al 2006;Maguire et al 2007;Hao et al 2009). Hao et al (2009) reported increases in manure pH, NH 4 ?…”

Greenhouse Gas Emissions from Housing and Manure Management Systems at Confined Livestock Operations

“…Numerous studies have revealed that reducing crude protein in the diet could substantially lessen nitrogen excretion and ammonia volatilization without compromising productivity [89][90][91][92][93]. Hao et al [94] studied the effects of DDGS on feces and manure composition in feedlot cattle and revealed that as the ratios of wheat DDGS (e.g., 0, 20, 40, and 60%) in animal diet increased (40 and 60% wheat DDGS), the likelihood of volatile fatty acids (VFAs) also increased. This led to the growth of odors produced from the breakdown of fiber and protein [89].…”

Use of Wheat Distiller Grains in Ruminant Diets

“…The resulting manure from catle fed wheat distiller grain, with high phosphorus content, can be beneicial for crop production, but it may also have a negative environmental impact due to increased phosphorus accumulation in crop lands surrounding feedlots [39]. Environmental concerns regarding phosphorus excretion are primarily associated with pollution of surface water.…”