Title: Evaluation of whole corn substitution in steam-flaked corn-based diets containing different concentrations of wet distiller's grains Authors
|Mcdaniel, Michael -|
|Walker, Derek -|
|Taylor, Kathryn -|
|Elam, Nathan -|
|Loest, Clint -|
Submitted to: American Society of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 30, 2011
Publication Date: August 1, 2011
Citation: McDaniel, M.R., Walker, D.A., Taylor, K.M., Elam, N.A., Cole, N.A., Loest, C.A. 2011. Evaluation of whole corn substitution in steam-flaked corn-based diets containing different concentrations of wet distiller's grains. In: Proceedings of the 2011 Western Section of the American Society of Animal Science Conference, June 21-23, 2011, Miles City, Missouri. 62:358-362. Interpretive Summary: In most beef cattle feedyard diets the corn is processed to increase its digestibility. In the Southern Great Plains the predominant processing method is steam-flaking. The process of making ethanol from grain results in the byproduct called distiller's grains. Distiller's grains can be used in cattle feeds, but research suggests it is not used well in diets based on steam-flaked corn. We hypothesized that because distiller's grains are used more efficiently in diets based on less processed corn, that it might be possible to replace a portion of steam-flaked corn with whole shelled corn in diets containing distiller's grains without adversely affecting animal performance or rumen function. This study was conducted to determine the effects of feeding 0 or 20% whole shelled corn in diets containing 0, 15 or 30% wet distiller's grains on performance and carcass characteristics of finishing beef heifers. Heifers were fed one of six diets for 108 days. Heifers fed diets containing 20% whole shelled corn had greater feed intake but average daily gain and feed efficiency were not affected. The percentage of carcasses grading USDA choice or better tended to be lower for cattle fed diets with 20% whole shelled corn. Increasing the concentration of wet distiller's grain in the diets tended to decrease average daily gain, increased feed intake, and decreased the gain-to-feed ratio. In summary, substituting 20% whole shelled corn for steam-flaked corn did not affect animal performance but decreased carcass quality. In contrast, substituting wet distiller's grain for steam-flaked corn decreased animal performance but did not affect carcass characteristics.
Technical Abstract: Substituting steam-flaked corn (SFC) with whole shelled corn (WSC) in finishing diets containing wet distiller's grains with solubles (WDGS) could reduce grain processing costs without affecting feedlot cattle performance, feed conversion, and carcass characteristics. This study used 642 Angus-cross heifers (412 +/- 18 kg initial body weight (BW)) assigned to 36 pens in a randomized complete block design (3 blocks based on initial BW). Treatments (2 x 3 factorial) were six finishing diets based on SFC with 0 or 20% WSC replacing SFC, and 0, 15, or 30% WDGS replacing SFC (DM basis). Diets were formulated to contain equal concentrations of rumen degradable protein (RDP) and fat, and were fed to heifers for 108 d. No WSC x WDGS interactions (P >/= 0.08) occurred for dry matter intake (DMI), average daily gain (ADG), G:F, and carcass characteristics. Heifers fed diets containing 20 vs 0% WSC had greater (P < 0.01) DMI, but final BW, ADG, and G:F were not affected (P >/= 0.11). The percentage of carcasses grading USDA choice or better tended to be lower (P = 0.07), and the percentage grading USDA select were higher (P = 0.03) for cattle fed diets with 20 vs 0% WSC. Other carcass characteristics, morbidity, and mortality were not affected (P >/= 0.16) by WSC. Increasing WDGS in SFC diets decreased final BW (linear, P < 0.01), tended to decrease ADG (linear, P = 0.10), tended to increase DMI (linear, P = 0.08), and decreased G:F (linear, P = 0.01). Addition of WDGS to SFC diets tended to decrease lot carcass weight (HCW) (linear, P = 0.09), but other carcass characteristics, morbidity, and mortality were not affected (P >/= 0.18). In summary, substituting SFC with 20% WSC in finishing diets did not affect animal performance and feed conversion, but decreased carcass quality. In contrast, substituting SFC in finishing diets with increasing amounts of WDGS decreased animal performance and feed conversion, but did not affect carcass characteristics. Limited responses to the substitution of 20% WSC could in part explain the lack of WSC x WDGS interactions. Thus, it is not clear if grain processing could be reduced in finishing diets containing WDGS without affecting feedlot cattle performance and feed conversion.