Nutrition and Management to Enhance Beef Cattle Productivity and Beef Safety

Non-Technical Summary: The continued growth of ethanol production in the US from cereal grains has dramatically heightened the importance of controlling feed costs and cost of gain by feedlot cattle for economic sustainability of feedyards. The increased demand for corn by the ethanol industry has been a key factor in increasing the futures price of corn grain as reported by the Chicago Board of Trade from approximately $3.00/bushel in August 2006 to recent peaks of approximately $4.30/bushel in February and June 2007. Consequently, a thorough understanding of the feeding value of alternative feedstuffs has become essential for nutritionists to predictably assess the relative value of a wide range of potential ration ingredients. An inherent challenge of utilizing alternative feedstuffs is developing an understanding of the impact of inclusion rate on gain efficiency and digestive deaths (caused by bloat, acidosis, poliencephalomalacia, and coccidiosis). Although the incidence of digestive deaths has been quite low historically (0.05 to 0.06%; Miles et al., 1998), some alternative feeds are either bloat-provocative or can contain high concentrations of sulfur and promote polioencephalomalacia. The vast majority of research on wet corn distillers grains has been performed in the Northern Plains of the US (North Dakota, South Dakota, Nebraska), which has the greatest density of ethanol plants. However, rations fed in the commercial feedlot industry in the Northern Plains are typically based on rolled corn and often do not contain supplemental fat. However, feedlots in the Southern Plains make extensive use of steam-flaked corn in rations and routinely include supplemental fat. Additional data describing the feeding value and management considerations for distiller's grains under conditions indicative of the Southern Plains feedlots are needed. A series of feedlot production studies employing pens of cattle to assess growth performance and carcass merit of cattle fed distillers grains will be used to address project objectives. It is expected that dqata from this research will be presented at technical meetings to convey the findings to industry nutritionists and that one peer-reviewed journal article will be published. <P> Approach: Three feedlot production studies employing pens of cattle will be used to examine growth performance and carcass merit of cattle fed distillers grains. These experiments will involve a total of approximately 1400 beef steers. In Trial 1, steers will be to one of seven treatments arranged in a 2 x 3 + 1 factorial. Treatments will include a standard control ration based on steam-flaked corn with urea and cottonseed meal as supplemental protein sources (13.5% CP, 3% NPN), and combinations of 15 or 30% of ration DM as wet corn distillers grains with 0, 1.5, or 3% NPN from urea. Before the study begins, one animal/pen will be identified for measurement of initial and final liver trace mineral content by biopsy. Plasma urea nitrogen will be determined for each animal at the beginning and the end of the study to assess protein status. Fresh feces will be obtained from the rectum at the end of the study for measurement of E. coli O157:H7 and Salmonella strains. A second sample of fresh feces will be collected to determine N and P content, and companion ration samples will be analyzed for N and P to calculate apparent digestion. Manure will be collected from the pen surface on approximately the same day to measure residual N and estimate ammonia volatilization. In Trial 2, steers will be assigned to five treatments including rations based on steam-flaked sorghum containing 0, 15, 30, or 45% of ration DM as wet corn distillers grains. Remaining procedures for liver biopsy, fecal and manure sample collection, and plasma urea nitrogen will be as in Trial 1. In Trial 3, steers will be assigned to five treatments arranged in a 2 x 2 + 1 factorial. Treatments will include rations based on steam-flaked corn with either 0% distillers or 15 or 30% distillers in the wet or dry form 0, 15, and 30% of ration DM as wet corn distillers grains. Remaining procedures for liver biopsy, fecal and manure sample collection, and blood sampling will be as in Trial 1.