Location: Livestock Nutrient Management Research2013 Annual Report
1a. Objectives (from AD-416):
The objectives of this cooperative research project are to (1) assess the effects of the wet cake to solubles ratio of distiller's grains with solubles on the performance and carcass characteristics of finishing beef cattle, (2) assess the effects of the wet cake to solubles ratio of distiller's grains on potential nitrogen and phosphorus losses from feedyards, and (3) assess the effects of the extent of dietary corn processing and wet distiller's grain concentration on energy metabolism of beef cattle.
1b. Approach (from AD-416):
The feeding value of wet distiller's grains with solubles for finishing beef cattle can be affected by the ratio of distiller's grain (i.e. wet cake) and solubles. However, to our knowledge, no research studies have been conducted to evaluate the effects of the cake:solubles ratio on animal performance when diets are based on steam flaked corn. These comparisons needed by nutritionists and feedlot managers so they can value different sources of distiller's grains. We propose a comparison involving combining the grains and solubles from a corn-ethanol plant at different ratios. In a feeding trial, 36 pens of beef steers (approximately 432 head with an average starting body weight of 650 lbs) will be fed one of four experimental diets with nine pens (12 head per pen) per treatment. Wet cake and solubles will be purchased separately from an ethanol plant in the area and will be mixed in the desired ratios at the WTAMU experimental feedlot. Experimental diets will include: 1) a control diet based on steam-flaked corn (SFC) with no distiller's grains or distiller's solubles, 2) a diet with 20% wet corn distiller's grains (i.e., wet cake) plus no condensed corn solubles, 3) a diet with 15% wet cake plus 5% condensed corn solubles, and 4) a diet with 10% wet cake plus 10% condensed corn solubles. Steers will be fed in open lot pens and slaughtered when backfat thickness is visually estimated to be 0.5 inches. Dry matter intake and averaged daily gain will be measured. Standard carcass measurements will be collected at slaughter. ARS personnel will obtain samples of diets, feed ingredients, fresh feces, and air dried manure for determination of nutrient excretion, and nitrogen volatilization losses. In a calorimetry study, six steers will be used in a 6 x 6 Latin square design. Treatments will be in a 2 x 3 factorial with 2 degrees of corn steam flaking (bushel weights of 24 or 28 lbs.) and three concentrations of wet distiller's grains (0, 15 or 30% of diet dry matter). Using open circuit, indirect respiration calorimeters, carbon dioxide and methane production and oxygen consumption of individual steers will be determined. Energy digestibility, heat production, energy retention, and dietary energy values will be determined.
3. Progress Report:
Previous research suggests there may be an interaction between corn processing and the feeding of wet distillers grains (a co-product of making ethanol from feed grains). Previous studies have compared steam-flaked corn to dry rolled corn-based diets. We are in the process of completing a performance study in which calves were fed steam-flaked corn-based diets that contained 0, 15, or 30% wet distiller's grains. The corn was steam flaked to weights of 24 or 28 pounds/bushel in order to have two levels of starch availability in the corn. Two blocks of cattle have been harvested and the third should be harvested in September 2013. The study has 8 pen replicates per treatment, with 10 calves in each pen. Groups of individually fed steers were harvested at 30-day intervals from approximately 700 to 1500 lb body weight. Samples of carcass, tissue, and bone were collected and analyzed for nitrogen, calcium, and phosphorus. Using these data, new equations and relationships will be developed for estimating nitrogen, calcium, and phosphorus retention in growing-finishing cattle. These data will be very important in developing updated nutrient requirements and for developing or improving models to predict nutrient retention and excretion. In a third study steers were individually fed steam-flaked corn-based finishing diets containing 0, 30, or 60% wet distillers grains. At slaughter, samples of digesta were obtained from different segments of the digestive tract and samples of tissues were obtained for trace mineral, sulfur, and enzyme analyses.