BIF-Proceedings-Final-flip

65 2018 BIF Research Symposium and Convention • Proceeding Papers Introduction In economic environments of rising feed costs, producers have become increasingly aware of the need to improve feed utilization in beef cattle. Traditionally, the beef industry had placed emphasis on improving output traits, such as fertility and live weight, to increase production profitability (Arthur et al., 2001; Hill, 2012) but the profitability of any agricultural production system is dependent on both output and inputs. As output traits (i.e. weight traits) are increased, there is a corresponding increase in input traits, such as feed (Meyer et al., 2008). Feed costs are reported as the largest expense to producers in the beef industry accounting for 50 to 70% of total production costs (Anderson et. al, 2005). It has been estimated that increasing performance (i.e. gain) by 10% would increase profits by 18%, this is compared to a 10% improvement of feed efficiency which has been estimated to increase profits by 43% ( www.beefefficiency.org) . The Alberta Agriculture and Rural Development (2006) reported that a 5% improvement in feed efficiency would have 4 times the economic effect of a 5% improvement in average daily gain. Therefore, decreasing feed costs without sacrificing animal performance could have a large impact on the profitability of a beef operation. Due to the large influence of feed costs on production profits, interest in selecting for cattle that are more feed efficient has increased. However, there is a debate as to what is the best phenotype for feed efficiency in cattle, how to incorporate it into a breeding program or genetic evaluation, and what impacts selection on feed intake or efficiency would have on other performance traits (Berry and Pryce, 2013). This essay will evaluate and contrast the various measures of feed efficiency, as well as the incorporation of these phenotypes into breeding programs and genetic evaluations. Literature Review 1. Measuring Feed Intake The ability to measure feed efficiency in cattle is dependent on the capability to measure individual feed intake and the integrity of the individual dry matter intake (DMI) records (Hill, 2012). Traditional methods of measuring intake involved housing animals individually. The collection Genetic Improvement of Feed Efficiency in Beef Cattle Miranda Culbertson, Department of Animal Sciences, Colorado State University of DMI on individually housed animals severely limited the number of animals that could be observed and thus limited the ability for estimation of reliable genetic parameters of DMI (Hill, 2012). Since the mid-1990’s there have been advancements in technology that has led to a large increase in the measurement of DMI for group housed animals (Cruz et al., 2011; Hill, 2012, Arthur et al., 2014). Research facilities and performance-testing centers have been equipped with technology for the capability to measure individual feed intake on group housed animals (Hill, 2012). The technology to measure feed intake must be capable of identifying individual animals, weighing rations fed to the individual animal, associate the measured feed consumed to the appropriate animal and compile the data into a useable format (Dahlke et al., 2008). Measuring feed intake is expensive, time consuming and testing facilities have a limited capacity for the measurement of individual feed intake (Wang et al., 2006; Nielsen et al., 2013). These limitations restrict the number of animals that can be measured within a year and therefore limit the amount of data generated for genetic evaluations. Currently, individual feed intake measurements are collected in feedlot environments and have a direct application to feedlot cattle. The translation of these feedlot- measured intakes to the cowherd grazing on rangeland is unknown. Approximately 50% of feed costs in the beef industry are attributed to the mature cow herd (Whisnant, USDA-NIFA-CRIS). To select for a cowherd that is more efficient in forage utilization, individual grazing intake needs to be measured. Currently there is no technology to effectively measure feed intake on a population of grazing cattle. Methods used for estimation of DMI for grazing animals lack precision and are often tedious, expensive and time-consuming (Undi et al., 2008). Current techniques for measuring grazing DMI typically involve digestive markers, group housed animals that measure herbage disappearance, or equations predicting DMI based on net energy requirements (NRC 2000; Meyer et al., 2008: Undi et al., 2008). 2. Phenotypic measurements of feed intake and efficiency Efficiency is defined as a level of performance that uses the lowest amount of input to obtain the greatest level of ~ 2018 Baker/Cundiff Award Recipient ~