Browsing by Subject "maintenance"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Effects of Dietary Energy Density and Intake on Maintenance Energy Requirements in Beef Cows(2014-12-11) Trubenbach, Levi AnthonyA variety of issues concerning the sustainability of beef production systems, including alternative land use decisions and liquidation in cow inventory, have magnified the need to enhance system efficiency. One approach to increasing production efficiency is through the intensification of cow-calf systems. In intensified systems cows will be housed in a controlled environment (i.e. drylot) for at least a portion of their reproductive cycle, subsequently offering the opportunity to develop nutritional manipulation strategies to optimize cow efficiency. An experiment was conducted to analyze the effects of dietary energy density and intake on maintenance energy requirements in beef cows. In a 2 x 2 factorial treatment arrangement, thirty-two crossbred cows were fed either a high- (H, 2.54 Mcal ME/kg) or a low-energy (L, 1.96 Mcal ME/kg) diet at one of two levels of intake (80; 80% NRC NE requirements, 120; 120% NRC NE requirements). Several methods using empirical equations were used to estimate body energy on d 0 and 56 as a proxy for RE. HE was calculated as the difference between ME and RE. Body weight gain tended to be greater (P = 0.08) in H than L, but was not different (P = 0.12) between 120 than 80. Retained energy tended to be greater (P ? 0.10) in H than L and greater (P ? 0.08) in 120 than 80. Heat energy per EBW^0.75 was greater (P < 0.01) in L than H and greater (P < 0.01) in 120 than 80, with no interaction (P = 0.29). Birth weight and adjusted 205-d weaning weight of the calves from treated cows were not affected by diet (P > 0.22) or level of intake (P > 0.56). Feed requirement for maintenance was calculated to be 92.54 and 168.06 kcal ME/EBW^0.75 for H and L, respectively. Fasting heat production was estimated to be 54.60 and 74.78 kcal/EBW^0.75 for H and L, respectively. Overall, increasing dietary energy density resulted in a decrease in maintenance requirements of approximately 28% and intake restriction decreased HE by approximately 28%, with no interaction, suggesting additive effects. Limit feeding high-energy diets to beef cows has the potential to increase the efficiency of production and land use in U.S. cow-calf systems.Item Methods for Identifying Best-Value Bid for Performance-based Maintenance Contracts(2011-02-22) Ahmed, JubairPerformance-based contracting (PBC) for roadway maintenance is relatively new among various alternative contracting options available at present and is increasingly drawing more attention from state Departments of Transportation (DOTs) and the contracting community. Because performance-based maintenance contracts extend over multiple years (typically 5-7 years) and shift performance risk to contractors, it is critical that contractors be selected based on a form of best-value method rather than on the conventional low-bid method. Currently, highway agencies use various methods for determining the best-value bid based on cost and technical scores. Five best-value bid identification methods that are already in practice by the state transportation agencies in Florida, Virginia, North Carolina, United Kingdom, and New Zealand were used as case studies for this research. These five methods were evaluated in terms of the agency?s willingness to pay for quality and the neutrality of these methods with respect to lowest bid and highest quality. To understand and describe the bid evaluation method, the agency can develop a willingness to pay (WTP) curve. This curve should represent the agency?s needs and budget, reflect their project characteristics, and accommodate associated performance risks. An Excel macro based software tool has been developed that automates these five best-value bid identification methods and also helps customize anyone of these options for any agency.