Finishing Cattle With Low Soluble Distillers Grains

Corn co-products, particularly wet or dry distillers grains plus solubles (DGS), have become popular ingredients in feedlot diets. This study by the University of Minnesota looks at the diets effect on animal performance, carcase and meat characteristics.

10 July 2010

4 minute read

Co-products of the ethanol industry are attractive feed ingredients due to their improved energy value relative to corn, price, availability, flexibility in feeding, and propensity to alleviate incidence and severity of acidosis (Stock et al., 2000). Due to increased feeding value of wet DGS compared to corn (up to 130 per cent the value of corn), performance and carcase characteristics of feedlot cattle were improved 30 to 40 per cent in most published research experiments conducted in Nebraska (Bremer et al., 2008).

Including wet DGS at levels up to 40 per cent of diet DM in place of corn grain improved feed-to-gain and increased ADG, marbling score, and backfat thickness (Bremer et al., 2008). Some research suggests that marbling score is reduced when feeding dry DGS at levels reaching 50 per cent dietary DM inclusion (Gunn et al., 2009); however, when feeding 15 or 30 per cent wet DGS (de Mello Jr. et al., 2008a) or 30 per cent dry DGS (Leupp et al., 2009) in finishing diets, marbling score, distribution, texture, and fat content were not influenced.

A recent study by Depenbusch et al. (2009) fed dry DGS up to 75 per cent dietary DM in steam-flaked corn-based diets to finishing heifers and observed a quadratic response in DMI, ADG, and final live BW as level of dry DGS inclusion increased. These performance variables were maximized at 15 per cent DM inclusion. Additionally, gain-to-feed and 12^th rib backfat depth linearly decreased as level of dry DGS was increased (Depenbusch et al., 2009).

Fatty acid composition influences beef quality (de Mello Jr. et al., 2008b). Increased concentrations of polyunsaturated fatty acids (PUFA) in beef products are associated with increased oxidation rates which leads to undesirable beef colour, off-flavors, and overall reduced shelf-life and consumer acceptance of beef retail products (de Mello Jr. et al., 2008b). Because DGS contains higher concentrations of PUFA than corn grain, beef products from cattle finished with elevated levels of DGS will contain higher concentrations of these fats (Depenbusch et al., 2009).

Therefore, beef product degradation is accelerated due to more rapid oxidation of the less stable PUFA which likely reduces shelf-life stability and consumer satisfaction. A study conducted by Roeber et al. (2005) indicates feeding DGS (either wet or dry) at high levels (40 to 50 per cent dietary DM) may negatively affect color stability of strip loins and ground product (Gunn et al., 2009) during retail display. However, the same experiment by Roeber et al. (2005) suggests feeding DGS (either wet or dry) at lower inclusion levels (10 to 25 per cent dietary DM) may maintain, or possibly enhance shelf life stability of cooked beef without affecting palatability.

Although color was affected, feeding DGS up to 50 per cent dietary DM inclusion did not impact tenderness or sensory attributes of beef (Roeber et al., 2005). In agreement, research suggests that inclusion of wet DGS (de Mello Jr. et al., 2008c) or dry DGS (Leupp et al., 2009) up to 30 per cent DM in finishing diets resulted in darker (less desirable) color scores of steaks, and thus reduced shelf life of these products.

In contrast, when dry DGS was included in steam-flaked corn-based diets fed to finishing heifers at levels up to 75 per cent dietary DM, overall tenderness increased linearly and juiciness, off-flavor intensity, and redness of steaks were not affected even though total PUFA increased linearly as level of dry DGS increased in the diet (Depenbusch et al., 2009). It appears results in both finishing performance and beef quality attributes of feedlot cattle fed varying levels of wet or dry DGS are not consistent. However, most research suggests the elevated concentrations of PUFA in the DGS may have the greatest influence on beef quality and sensory characteristics.

Alternative production of DDGS has developed a low solubles dry DGS (LSDDG) with lower concentrations of lipid compared to conventional DGS. An opportunity exists to develop a feeding strategy that includes LSDDG to reduce negative effects of PUFA on quality and shelf-life stability of the resultant beef retail products.

The objective of the current research project is to evaluate the effect of finishing cattle with LSDDG compared to conventional DGS and corn-based diets on animal performance, carcase characteristics, and beef quality in regards to shelf-life stability and sensory and physico-chemical characteristics.