Roundup 1999

Roundup is the major beef cattle education and outreach event sponsored by the Agricultural Research Center-Hays. The purpose is to communicate timely, applicable research information to producers and extension personnel. The research program of the Agricultural Research Southeast Agricultural Research Center Center-Hays is dedicated to serving the people of Kansas by developing new knowledge and technology to stabilize and sustain long-term production of food and fiber in a manner consistent with conservation of natural resources, protection of the environment, and assurance of food safety. Primary emphasis is on production efficiency through optimization of inputs in order to increase profit margins for producers in the long term. Roundup 1999 was held at the Agricultural Research Southeast Agricultural Research Center Center--Hays, KS, April 1, 199

Economically Optimal Distiller Grain Inclusion in Beef Feedlot Rations: Recognition of Omitted Factors

With the rapid expansion of the ethanol industry, the feeding landscape familiar to the feedlot industry is changing. While concerns regarding rising corn prices persist, many within the industry are looking at distillers grains, a by-product of ethanol production, to serve as a feed substitute. The question remains as to what extent these two feed sources are substitutable. The purpose of this study is to identify the economically optimal inclusion rate of distillers grains in beef feedlot rations, considering an array of often omitted factors. Most currently prevailing recommendation rates are strictly biologically based and frequently reference only one feeding trial. Unique economic factors considered in this research include the impact of by-product inclusion rates on animal performance (utilizing recently conducted meta-analysis from 17 relevant feeding trials), enhanced likelihood of death loss from heightened sulfur content, and manure disposal costs. Results indicate that excluding these factors can significantly impact optimal inclusion levels and that reliance on a single or few feeding trials may greatly bias results.Livestock Production/Industries,

Model development for the prediction of intake and carcass measures to be used as economic marketing determinants for calf-fed steers

Accurate prediction of intake and carcass characteristics can assist in projecting input costs and potential premiums when cattle are sold at optimum finishing so net profit/loss can be anticipated. Currently published DMI prediction equations and dietary NE values are based off of data collected over 50 years ago and have been shown to inaccurately predict intake compared to a prediction equation based of off performance data. Calculating dietary NE values from performance data increased precision and accuracy of prediction. Additionally, prediction accuracy was increased for diets containing ethanol byproducts. Since ethanol byproducts have been shown to have 110 to 140% the feeding value of corn, the improvement in predicting intake illustrated the need for research to more accurately defining feedstuff energy values via performance data and using that information to derive new intake prediction equations. Even so, predicting optimum endpoint for the producer can be the most economically beneficial prediction since carcasses are awarded premiums for high cutability and high quality grades. It has been found that predicting marbling score by measuring backfat and BW over the feeding period seems to be the most viable and accurate compared to other model combinations of backfat, BW and DMI. However, backfat and BW are not synonymous with marbling score and therefore, bias increases at the end of the feeding period. Still, the economic advantage may be given to feeding the animal longer as a greater return was found for projections of animals fed past the 1.2 cm optimum backfat. Since carcass gain can be up to 90% of total gain at the end of the feeding period, it is beneficial for the producer to feed cattle longer as the cost of gain is spread over more carcass weight. The resulting paradigm shift to feeding cattle what is deemed past industry optimum will lead to greater carcass weights, higher quality grades, and ultimately greater premiums for the producer. Advisors: Larry L. Berger and Galen E. Erickso

Evaluation of the NRC (2000) Beef Model for Predicting Performance and Energy Requirements of Cattle Fed under Western Canadian Environmental Conditions

The NRC (2000) beef model is widely used to evaluate nutrient requirements and feeding programs for cattle. The objectives of this study were to assess the accuracy and precision of the NRC (2000) beef model in predicting dry matter intake (DMI), shrunk weight gain (SWG), net energy of maintenance (NEm) and gain (NEg) requirements and also to determine the relationship of body condition score (BCS) and ultrasound subcutaneous fat thickness (USF) to total body fat of steers fed under western Canadian environmental conditions. Data used for this study was from Basarab et al. (2003). The study was conducted over two years using a total of 176 steers. The DMI, SWG, NEm and NEg for each steer were modeled using the NRC (2000) beef model under actual environmental and thermoneutral conditions. Retained energy (NEg) was calculated for each animal based on initial and final body composition. Actual NEm utilized was calculated by subtracting NEg adjusted for the efficiency of metabolizable energy used for gain (kg) from total metabolizable energy consumed and by adjusting for the efficiency by which metabolizable energy is used for maintenance (km). The accuracy of predicted values was evaluated by means comparison, regression and residual analysis, concordance correlation coefficient (CCC) and reliability index methods. Dry matter intake was over predicted (P0.05) under all methods investigated with a general over prediction for NEm and under prediction for NEg under actual environmental and thermoneutral conditions. Cattle NEg was under predicted, possibly explaining why SWG was under predicted. Potential reasons for this inaccuracy includes failure to account for specific physiological and behavioral adjustments such as changes in organ size, passage rate, hide thickness influencing the NEm calculation and in the case of NEg due to the lack of precise knowledge of actual composition of gain by growing steers due to lack of specificity of initial body composition. Body condition score and USF had a comparably strong relationships to total body fat (P<0.05, adjusted r2= 0.55 or 0.56, respectively), suggesting potential for their use in improving composition of gain predictions (P<0.05)

III Encontro de Jovens Investigadores do Instituto Politécnico de Bragança: livro de resumos

O presente trabalho resulta do conjunto de apresentações no III Encontro de Jovens Investigadores do Instituto Politécnico de Bragança, de 11 a 13 de Novembro de 201