As ethanol producers continue to seek greater value from a grain, adoption of oil extraction via front-end fractionation of the whole kernel prior to fermentation or through back-end centrifugation of the thin stillage stream contributes to varying nutrient composition and feeding value of distillers grains with solubles (DGS). The impact of oil extraction on finishing feedlot cattle performance and resulting energy values is an item of interest to cattle feeders and nutritionists. Thus, two studies were conducted: a 181-d finishing feedlot experiment and a meta-analysis of published data, to determine effects of oil extraction on finishing cattle performance and resulting energy values. Effects of feeding reduced-fat (RF) modified wet distillers grains with solubles (MDGS) on finishing cattle performance, carcass characteristics, and resulting energy values were evaluated in Study 1. Linear contrasts in experiment 1 demonstrated that feeding RF MDGS at 30 and 45% inclusion (high inclusion) led to cattle consuming more DM than feeding full-fat (FF) or RF MDGS at 15% inclusion. There were no significant differences in all other performance variables, carcass characteristics or resulting energy values. Study 2 was conducted utilizing a meta-analysis approach to determine the energy value of oil extracted corn distillers grains with solubles (DGS) in finishing feedlot cattle diets. Results from Study 2 revealed that feeding FF DGS resulted in greater ADG compared to feeding RF DGS or control diets, and feeding RF DGS resulted in greater ADG compared to feeding control diets. At increasing DGS inclusion, feeding FF DGS led to lower DMI than feeding RF DGS. Feeding DGS at moderate or high inclusion, regardless of fat content, resulted in greater feed conversion efficiency compared to feeding control diets. At high inclusion, feeding FF DGS led to greater feed conversion efficiency than feeding RF DGS. Feeding FF DGS at moderate or high inclusion or RF DGS at moderate inclusion resulted in greater observed ME concentration compared to feeding control diets. One unit of ether extract (EE) from DGS contributed 0.06 Mcal ME/kg DM to dietary ME. Results of the meta-analysis demonstrated that reducing oil content of corn DGS reduced energy value of the DGS, thus corrections to energy content of currently available DGS are required. A third experiment was conducted to characterize the nutrient content of corn plant components at various corn crop harvest endpoints. Through reproductive stages of development, corn plant DM increased until dry corn grain harvest. Concurrently; NDF, ADF, and CP concentrations decrease as the plant matures while ether extract (EE) increases once the plant reaches physiological maturity. When concluding the results of this experiment in terms of a producer growing corn as a feed resource for cattle, it is recommended that scouting of corn fields begins once pollination occurs. By beginning to scout fields at the beginning of reproduction, producers can then closely monitor plant DM in order to harvest various corn crop endpoints at their ideal time.
University of Minnesota M.S. thesis. October 2015. Major: Animal Sciences. Advisor: Alfredo DiCostanzo. 1 computer file (PDF); ix, 118 pages.
Utilizing Reduced-Oil Corn Distillers Grains with Solubles in Finishing Beef Cattle Diets.
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