Interpretive Summary: Effects of supplemental fat concentration on feeding logistics, animal performance, and nutrient losses of heifers fed finishing diets based on steam flaked corn and sorghum-based distiller’s grains.
By: Dr. Thomas Powell
Distillers grains are a common ingredient in beef cattle finishing diets. A co-product of the ethanol industry, they are high in energy and a source of crude protein. Corn-based distiller’s grains have received much attention in the scientific literature, particularly in diet formulations common to the Northern Great Plains. Much less is known about sorghum wet distiller’s grains with solubles (SWDGS) produced in the Southern Great Plains. Beef cattle diets in this region typically use steam-flaked corn (SFC) and supplemental fat along with SWDGS.
A team of researchers from West Texas A&M University, USDA-ARS Conservation and Production Research Laboratory, Universidad San Francisco de Quito, and Texas A&M AgriLife Research recently published in the Journal of Animal Science the results of a study examining SWDGS as a component in a typical beef finishing ration. Their objective was to determine the effects of supplementing SFC-based diets with SWDGS and fat on animal performance and carcass characteristics.
Three hundred ninety-eight British and Continental crossbred heifers were blocked by weight and randomly assigned to one of 40 pens. Each pen was fed one of 5 experimental diets. Two 92% concentrated diets based on SFC with 0 or 3% added fat from yellow grease and three 92% concentrate diets with 15% SWDGS and 0, 1.5 or 3% added fat comprised the treatments. Performance factors including dry matter intake (DMI), water intake and average daily gain (ADG) were recorded during the study. Plasma urea nitrogen concentrations were measured on all heifers at the beginning and end of the feeding trial. Heifers were slaughtered and carcass data collected when estimated backfat reached 1.27 cm. with total days on feed ranging from 82 to 134 days.
DMI and ADG were higher for heifers on the SWDGS diets. Within the SWDGS diets, DMI and ADG tended to peak with the intermediate (1.5%) added fat level. The ratio of ADG:DMI tended to increase as more fat was added to the SWDGS diets. The heifers fed SWDGS had higher hot carcass weights. Yield and quality factors increased with increasing levels of added fat as would be expected based on numerous other studies. Nitrogen intake and excretion were greater in heifers fed SWDGS but with lower nitrogen loss as a percentage of intake. Researchers concluded that adding 1.5% fat to cattle finishing diets containing 15% SWDGS could improve performance.
A novel addition to the study was the consideration of feeding logistics. Given the relative density of the diets and the amount of feed consumed, a feedyard would need to deliver 11% more loads of feed when using 15% SWDGS compared to 0% SWDGS. This report recommends that any consideration of diet formulation using SWDGS account for the differences in feed milling and delivery costs.
To view the full article, visit the Journal of Animal Science.