Duration: 10/01/2008 to 09/30/2013

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

The overall goal of this cooperative, multi-state, multidisciplinary, research and outreach project is to improve feed efficiency and profitability of meat production in beef cattle. The scope of this project will include measures of feed efficiency (FE) that utilize individual animal to animal variation in feed intake. One of the best characterized of these is known by several terms: net feed efficiency (NFE), residual feed intake (RFI), and net feed intake. We will use RFI throughout this document.

We provide here a definition of RFI: Residual feed intake measures the variation in feed intake beyond that needed to support maintenance and growth requirements, and is calculated as the difference between actual feed intake and the feed an animal is expected to consume based on its body weight and average daily gain. Cattle that eat less than expected for their body weight and average daily gain have negative RFI, which equates to improved feed efficiency.

This concept is becoming established, worldwide as the most beneficial approach to improving feed efficiency. This regional project will coordinate efforts across the nation to incorporate elements of genetic improvement in feed efficiency, understanding the interaction of animal life-stage in refining definitions of feed efficiency, understanding the underlying biological drivers of variation in feed efficiency and in interacting with industry to cooperatively disseminate this important information to US beef cattle producers through a strong, integrated outreach program.

This proposal describes the collaborative efforts of nine Agricultural Experiment Stations, and features additional collaboration of international scientists. Major points that support the establishment and continuation of this important, research and outreach project for the next five years are:
1. The project relates to a major agricultural problem. Meeting consumer needs for a high quality product while maintaining profitability of production, decreasing environmental impacts, and minimizing use of natural resources will require improvements in the efficiency of meat production in beef cattle.
2. The project relates directly to the objectives of the CSREES Strategic Plan 2007-2012:
Objective 2.1: provide research, education, and extension to expand domestic market opportunities. This project will directly contribute to two of the Key Outcomes of this sub-objective: expand science-based knowledge and technologies to generate high-quality products and processes by: increasing knowledge of biomass conversion, and establishing new integrated research and extension programs.
Objective 2.2: provide research, education, and extension to increase the efficiency of agricultural production and marketing systems. This project will directly contribute to two Key Outcomes under this sub objective: increase efficiency of agricultural production system by: expanding information to model feed utilization for animal species, and further understanding the biological role of gene sequences in animals.
Objective 3.2: provide research, education, and extension to improve the quality of life in rural areas. This project will directly contribute to the Key Outcome of this sub objective: increased knowledge among county based staff and community leadership in order to provide research-based practices to encourage appropriate community capitol development which enhances business and economic development. Electronic deployment of information to increase the, human and economic capitol available for more nimble and creative community responses to needs.
Objective 6.2: enhance soil quality to maintain productive working lands: This project will directly contribute to the Key Outcome of this sub objective: expand and disseminate science-based knowledge and information for management of the nations natural resources and environment, including soil, air and water, in agricultural and range working lands and ecosystems.
3. National importance of building this multi-state project: Across the nation, individual research and outreach efforts with RFI at the focal point, are rapidly expanding. Industry at multiple levels is embracing RFI as a priority for development. Participants in this multi-state project are also playing national roles at multiple levels. For example, the Beef Improvement Federation has established a sub-committee to develop national standards for conducting feed efficiency measurement (several multi-state project participants are members of this committee). Members are also active in various roles in the National Beef Cattle Evaluation Consortium. It will be imperative that this multi-state project plays a leading role in coordinating scientific information and in advising the development of national standards and protocols. In addition, the synergy that will be developed across this large team of researchers will convert projects with local or regional impact to having national and international impact.
4. All of the projects outlined in the following Methods section are technically sound and are in different stages of progress. Many of these have been peer reviewed and are presently contributing impact at the state, regional or local levels.
5. This project is both a multi-state and a multidisciplinary project, involving the effort of investigators at nine different State Agricultural Experiment Stations and international collaborators in Australia and Canada. The Principal Investigators represent a variety of basic and applied science disciplines and outreach expertise that complement each other and provide the skill-sets necessary to complete the objectives.
6. The project will involve a strong cooperative effort between the various units including exchange of reagents, cDNA probes, and an RFI phenotype database as well as the sharing of knowledge and techniques, joint use of equipment and techniques available at particular stations, and joint publication of research results. Numerous collaborative projects are described in the procedures for the proposal. The committee feels strongly that the collaborations in this project would have been substantially more difficult to establish and maintain outside the framework of a funded regional project.
7. The members of the committee have been highly successful in obtaining outside support to fund the research. Funding from the USDA NRICGP Program, and other granting agencies, and industry sources has been essential to carry out the work and to maintain the high level of productivity of the group, and this record of outside funding is expected to continue.
8. This project describes a basic and applied research and outreach approach to an important agricultural problem. The investigators at the cooperating stations have already demonstrated a high level of productivity, and are, thus, capable of making substantial progress towards the objectives outlined in this project proposal.
9. The impacts from completion of this multi-state project will be national and international in scope. This project will contribute scientific rigor to the development of national standards for feed efficiency testing. It will provide unifying standards that will be implemented across national breed associations and state cattle associations. It will contribute to understanding of the underlying biological drivers of variation in feed efficiency and contribute to development of biologically-based predictors and improve the accuracy and reliability of mathematic models to predict feed intake in beef cattle.

Related, Current and Previous Work

To calculate RFI, animals are tested within management group, cohort, and sex. Data from individual animals are plotted as feed intake versus live weight gain and a linear regression of the data is calculated. For each animal data point the residual on the regression is calculated as its RFI value. Thus, data points below the regression line represent animals that eat less than expected (negative RFI, efficient) while data points above the regression line represent animals that eat more than expected (positive RFI, inefficient). RFI calculated in this way is robust and comparable among test cohorts (1, 2, 4, 12).

RFI is becoming a broadly accepted gold standard for FE in the research community because it is superior to other FE measures. At the March 3, 2003 meeting of the WCC092 Committee on Beef Cattle Energetics, one of three impact statements composed by participants, stated that Residual Feed Intake (RFI) is the tool identified most often as the one which should have priority in development of quantitative assessment of efficiency in animal performance (report available at http://lgu.umd.edu/lgu_v2/homepages/saes.cfm?trackID=398#2).

Although the potential for improvement in FE arguably will have the greatest economic impact on beef production, it is essential that interactions with other production parameters and product quality are considered in development of any new performance trait. One of the greatest advantages in using RFI as an efficiency trait is that it appears to be independent of most other performance traits that have so far been evaluated. Thus, it is ideal for use in multi-trait selection indices and other broad-based performance evaluations. Consistent with research in other countries, we have found that there appears to be little relationship between RFI and measures of carcass and product quality in Angus cattle, such as longissimus muscle area (LMA), fat thickness (FT), yield grade (YG), or quality grade or tenderness (5). Thus, our present knowledge indicates that RFI has potential for industry adoption with little risk or association of adverse traits.

A second efficiency issue of great interest to industry is to understand the relationships between efficiency of production for cow-calf producers and efficiency in the feedlot. It appears from studies conducted in other countries that an RFI value determined in a post-weaning test is robust and consistent across life-stages. An initial study on a small population of Angus steers suggested that RFI was consistent in the post-weaning and finishing life-stages in beef cattle (8). Improvement of FE across life-stages requires further study and validation in beef cattle in the United States.

World context of Residual Feed Intake.
Cost of production is the largest cost variable over which a producer has control in the profitability equation. Only by reducing cost of production (via reduced feed intake, for instance), will U.S. beef producers be able to remain competitive and sustainable in a global marketplace. To reduce feed cost, RFI is being utilized as a measure of efficiency in beef cattle production in Australia and is being implemented in Canada. Australian researchers have shown that RFI is independent of many other production parameters. As a result, it is now being used in a selection index to simultaneously target efficiency and other parameters such as performance and product quality (3).

RFI Relationship to Other Performance Traits and Carcass Characteristics.
Many examples in the literature suggest there is little relationship between RFI and growth or partitioning of growth between fat and lean deposition (1, 2, 4-6, 11, 21). Other parameters, such as the relationship between RFI and DMI, and RFI and FCR appear to show consistent relationships across the literature. Herd and Bishop (15) and Arthur et al. (4) reported moderately positive phenotypic correlations between RFI and DMI of Hereford, Angus, and Charolais cattle. Consistent with these reports, Baker et al., (5) have also found a positive correlation (r = 0.59) between RFI and DMI in Angus steers. Data describing the relationship between FCR and RFI (r = 0.70(5)) are consistent with other reports (4, 6, 15) that also describe correlations between FCR and RFI (r = 0.53, 0.44 and 0.37 respectively). Thus, any selection for RFI will need to account for its relationship with intake. Because intake is highly correlated to growth potential, multi-trait selection including growth or intake together with RFI will ensure that unintended selection for lower intake that might be a potential undesirable artifact of selecting for RFI alone does not become a problem.

The possibility of detrimental effects on carcass characteristics associated with RFI needs careful consideration. Some studies have shown that there may be a tendency for more efficient animals to be leaner. If this is so, the effects of selection for RFI on product quality warrants further investigation. Herd and Bishop (15) reported negative phenotypic (r = -0.22) and genetic (r = -0.43) correlations between RFI and estimated lean content in Hereford cattle. Additionally, reports on the relationship between RFI and intramuscular fat are not conclusive. Robinson et al. (28) reported a small, positive genetic correlation (r = 0.17) between RFI and IMF. McDonagh et al. (19) found no differences in visual marbling scores or objectively measured IMF for carcasses of a group of Angus, Angus x Hereford, Angus x Polled Hereford, and Angus x Shorthorn offspring steers from high or low RFI selection lines. Nevertheless, Richardson et al. (27) reported progeny from Angus cattle selected for low RFI had 13.2% less subcutaneous and intramuscular fat than progeny from those selected for high RFI. Differences between these studies may result from differences in age and maturity of animals when the traits were measured or these contrasting results may suggest that other unidentified variables may influence these specific populations.

Reports of correlations between RFI and ultrasound measurements of subcutaneous fat, IMF, rump fat, and carcass fat are also inconclusive. Arthur et al. (4) reported low phenotypic (r = 0.14) and genotypic (r = 0.l7) correlations between RFI and ultrasound rib fat thickness (FT) and longissimus muscle area. In a preliminary study, Crews et al. (11) reported negative correlations between RFI and ultrasound FT and marbling scores. Carstens et al. (10) found that high RFI steers had greater rump fat thickness but similar FT and IMF compared to low RFI steers. It is possible that less efficient steers (high RFI) have a greater propensity to deposit fat rather than protein. Studies that report lower subcutaneous fat thickness in low RFI (more efficient) steers, also report no apparent reduction in HCW or longissimus muscle area. These findings suggest that yield grade is not compromised, and that low RFI steers may actually have increased retail meat yield. Nevertheless, other authors propose that further selection for low RFI may decrease subcutaneous fat levels, possibly resulting in animals that fail to meet minimum market specifications for fatness (19). However, data from US Angus steers do not support this notion, as carcasses from all groups had acceptable quality and yield grades (5).The problem of a possible antagonistic association between fat thickness, marbling, and RFI will continue to require attention. This is unlikely to become a problem in production systems because producers are acutely aware of the economic benefits of selection for marbling. A recent investigation considered this issue and identified the traits of Angus sires, which had been widely used in Australia. Exton et al. (13) were able to identify individual bulls that had combined traits of desirable FT, IMF, and RFI.

Factors that Determine RFI.
Performance traits and their correlations with RFI and FCR are well documented in the literature; however, the biological drivers of variation in RFI are largely unknown. Richardson and Herd (26) suggested that variation in at least seven major biological processes contributes to variation in RFI: protein turnover, tissue metabolism and stress, heat increment of fermentation, ability to digest feed, activity, body composition, feeding patterns, and other unknown contributors. Furthermore, modulation of energy use via physiological processes appears to have the potential to account for a substantial proportion of individual variation in efficiency (16).

Nkrumah et al. 2006 (24) found that RFI was correlated with daily methane production and energy lost as methane (r = 0.44; P < 0.05). Methane production was 28 and 24% less in low-RFI animals compared with high- and medium-RFI animals, respectively. RFI was also correlated with digestible and metabolizable energy intakes and heat production. Thus, it appears that there are also implications for RFI for the environmental sustainability of beef production.

According to Rauw et al. (25), the residual feed intake of an individual may also be related to the amount of buffer resources it has available to processes such as physical activity and the ability to cope with unexpected stresses. Thus a more complete understanding of the effects of stress and whether there is a need to build into selection strategies, a metabolic reserve component for unforeseen energy demand must also be considered. Given the present lack of understanding of the biological basis of RFI and its effect on various traits, any selection for RFI in beef cattle systems should be accompanied by monitoring for correlated responses. The proposed research will improve understanding of the possible effects of RFI on end-product quality.

RFI as a Genetic Selection Tool.
Since RFI is moderately heritable (h2 = 0.16 to 0.43 (14)), it offers a genetic selection criterion to improve beef cattle efficiency without also increasing growth rate and mature size. Selection for efficiency using the RFI trait could potentially improve FE in cattle through reduced feed intake for a similar level of growth performance (14). Selection of parents with low RFI (efficient) resulted in progeny that consumed less feed as yearlings but weighed the same at harvest as offspring from high RFI parents (27). In addition, preliminary evidence suggests that selection for RFI probably does not negatively affect mature cow weight or carcass quality of progeny, but can offer an advantage in selection for reduced cow maintenance requirements (15).

Since feed cost comprises the largest cost on most beef cow/calf and feedyard operations, efforts to reduce feed costs without negatively affecting growth, reproduction, performance, or meat quality would be extremely beneficial to the industry. However, cost-effective methods of characterizing large numbers of cattle for RFI (in order to allow genetic selection for RFI) are not yet widespread. Based on the substantial amount of variation present in RFI within a population, it is likely that commercial cow/calf producers will demand an EPD for efficiency from their seedstock suppliers. As a result, future cattle selection will probably include the conventional growth and carcass traits, newly-expanding reproduction traits, and efficiency traits such as RFI.

Indicator Traits for RFI.
One of the greatest impediments to implementing RFI is the cost of identifying sires with superior RFI. Reliable data generation requires that at least 15 progeny per sire (minimum) are RFI-evaluated in a post-weaning test. Increasing the number of progeny evaluated improves the accuracy of the trait estimate. Thus, there is a high cost associated with collecting these data. Researchers have recently begun to search for useful indicator traits for RFI. Easily measured plasma hormones have been suggested as possible candidates. Moore et al. (20) reported that plasma IGF-I concentrations were genetically correlated with RFI (0.56) in growing cattle, and Brown et al. (7) found that calves with low RFI had 25 to 29% lower serum IGF-I than high RFI calves, suggesting that IGF-I may be a useful physiological biomarker of RFI. The Australian beef industry has been using serum IGF-1 at weaning to supplement data supporting a breeding value for RFI based on standard testing. Recent interest of commercial sectors of the beef cattle industry in the United States, in IGF-1 as an indicator for RFI has stimulated discussion among scientists with expertise in this area. Due to uncertainty surrounding the reliability of serum IGF-1 as an indicator trait for RFI, scientists leading this field developed a position paper recommending that further research within the United States is required before IGF-1 can be broadly implemented as an indicator trait (9).

Several candidate genes as markers for RFI have been proposed. A polymorphism in the leptin gene (21, 22) appears to be related to gain in backfat thickness (P = 0.02), ultrasound backfat thickness (P = 0.07), and lean meat yield (P = 0.007). This study also suggested that this leptin polymorphism may have potential for predicting RFI; however the relationship in the report was not convincing (P = 0.23). Further studies by this research group have indicated that polymorphisms in the leptin promoter may have potential to predict intake and possibly RFI (23). Other research teams have considered several mechanisms related to metabolic efficiency as potential drivers of variation in RFI. Variation in mitochondrial efficiency (7, 17, 18) appears to be a promising area of mechanistic research that will contribute to our understanding of RFI variation.

Because RFI is a polygenic trait, it seems unlikely that a single indicator gene will be discovered. It is more likely that a panel of indicators (for example, gene polymorphisms, including mitochondrial gene polymorphisms, plasma IGF-1) will provide a more powerful tool. It is clear that much basic research is needed to discover the underlying mechanisms that contribute to variation in RFI. As we accumulate data on accurately characterized bulls that are divergent for RFI, it will become possible to investigate these underlying mechanisms.

It is likely that in the future the cost of evaluating RFI will be reduced through use of indicator traits. However, data from indicator traits will still need to be validated and referenced to absolute measures of RFI. Thus, it will be essential to continue to evaluate a proportion of animals using a standardized animal testing protocol.
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There is almost no duplication between this project and any other funded multi-state (regional) project. Searching the CRIS Multi-State Projects database yielded the following projects that address either efficiency of feed utilization or genomics-based or genetic selection strategies. Each of these has distinctly different objectives to the present proposal. The following projects address objectives that focus upon management of beef cattle or the manipulation of the nutrient value of feeds:

NCCC206: Nutrition and Management of Feedlot Cattle to Optimize Performance, Carcass Value and Environmental Compatability.

NCERA087: Beef-Cow-Calf Nutrition and Management Committee.

NC1020: Beef Cattle Grazing Systems that Improve Production and Profitability While Minimizing Risk and Environmental Impacts.

The following projects focus across multiple issues of genetic manipulation and genomics:
NCCC_OLD204: The Interface of Molecular and Quantitative Genetics in Plant and Animal Breeding.

NCDC213: Interpreting Cattle Genomic Data: Biology, Applications and Outreach.

NCERA199: Implementation and Strategies for National Beef Cattle Genetic Evaluation.

NRSP008: National Animal Genome Research Program

WERA-1 Beef Cattle Breeding in the Western Region

None of these projects focus specifically on the genetic basis of variation in feed efficiency and its underlying biological drivers. Many of the objectives of these other projects are complimentary to those of the present multi-state project proposal.

Whenever appropriate, committee members will maintain communication with these groups through collaborative research efforts and attendance at meetings of these groups. However, the research objectives of those committees touch upon those of this committee only peripherally. The objectives of this proposal are unique to this committee in their emphasis on feed efficiency in beef cattle.

As described above, members of the regional project have made significant contributions to both applied and mechanistic research underpinning RFI and feed efficiency. In addition, members play an active role in outreach, disseminating knowledge and implementing RFI as a gold standard of efficiency across the United States beef industry. The studies proposed for this project build upon these findings and will further increase our knowledge of the sources of variation in feed efficiency.

Objectives

1. To understand biological sources of variation in efficiency of feed utilization as quantified by traits like RFI.
   
2. To discover physiological biomarkers and genetic markers for RFI.
   
3. To determine the relationships between RFI and efficiency of feed utilization in stocker, feedlot and cow-calf sectors.
   
4. To examine the effects of selection for RFI on other economically relevant traits.
   
5. To develop EPDs, multi-trait selection indices and decision-support tools to facilitate selection for improved feed efficiency in beef cattle.
   
6. 6. To develop producer educational programs to enhance technology adoption by the beef industry.
   

Methods

By working cooperatively across this multi-state project, scientists in the participating Experiment Stations will build synergy and will expand their focus from the regional and state levels to have national and international impact. 1. To understand biological sources of variation in efficiency of feed utilization as quantified by traits like RFI. Studies under this objective will focus primarily on identification of the sources and quantification of the magnitude of the biological drivers of variation in RFI. The following Experiment Stations will work in collaboration on this objective: Alabama, California, Idaho, Illinois, Missouri, Nevada, Texas and West Virginia. Preliminary work in California, Texas and Missouri has shown that differences in RFI are related to variation in maintenance energy requirement, which in turn is related to rates of body protein turnover. Collaboratively, we will determine the range in RFI that exists within the beef population. Outlier animals will be used to identify hormonal, cellular respiration, and energetic differences responsible for differences in RFI among animals. DNA will also be collected from these animals to be used in objective 2. These experiment stations will also produce matings from sires phenotyped for RFI. The offspring from these matings will be used to determine the impact of selection for RFI on efficiency of cattle managed on forage and concentrate diets and performance of feedlot cattle and females retained as cows as described under objective 3. Preliminary research with yearling steers from known parental RFI matings has demonstrated differences in forage intake and utilization between negative and positive RFI sired bulls. Potential intake and metabolic efficiency driven differences in gain when forage was lush and plentiful as well as when forage was more mature and limiting were evident. Other preliminary research demonstrated that diet formulations can reduce manure volume output by 60% during the growth phase and 40% during the fattening phase of feedlot production. Preliminary research has also shown that intake within a population of beef cattle varies by 1.4 fold. Because waste ouput is a function of feed intake, the potential to select for efficient animals that are 40% more efficient would be expected to reduce waste output and methane emission by the same margin. The Idaho, Missouri, Nevada and West Virginia Experiment Stations will collaborate to measure the difference in waste volume and methane output in animals that are efficient (negative RFI), average (RFI ~ 0), and inefficient (positive RFI). These data will be used to determine the potential improvement that can be made in waste output reductions via selecting for RFI. These determinations will be made for forage-based diets and grain-based diets designed to maximize efficiency. These measurements will also be made on offspring generated from matings using negative and positive RFI sires. These data will be used to determine the potential improvement that can be made from genetic selection for improved efficiency (negative RFI). The geographical diversity of the participating experiment stations will allow us to RFI phenotype progeny from the same bulls that are raised in widely different environments. DNA will also be collected from progeny born from sub-tropical to cool temperate environments. This will provide information on the effect of environment in estimating RFI. 2. To discover physiological biomarkers and genetic markers for RFI. Establishment of well-characterized populations of beef cattle across member experiment station herds and collaborating industry herds will provide the resource for this objective. In addition, outcomes from Objective 1, understanding the biological drivers of variation in RFI will contribute knowledge of candidate mechanistic pathways and candidate genes for study of potential physiological biomarkers and gene markers for RFI. The Alabama, Idaho, Missouri, Nevada, Ohio, Texas and West Virginia Experiment Stations will collaborate to identify genetic and physiological biomarkers for ranking RFI phenotypes of cattle. The Idaho, Missouri, Ohio and Texas Experiment Stations will lead the study of blood metabolites and hormonal profiles unique to RFI phenotype. As referenced above previous research has demonstrated that IGF-I from blood taken at weaning in Bos taurus cattle is correlated to RFI phenotype. A standard commercially available ELISA will be used to assay plasma IGF-I. The Ohio station has been divergently selecting for blood serum IGF-I concentration in purebred Angus cattle since 1989. These divergent IGF-I selection lines will be characterized for differences in RFI via collaboration with the Texas experiment stations. Missouri and Texas will lead research studying the relationship of mitochondrial respiration to RFI phenotype. Previous research demonstrated that rate of oxygen uptake by the mitochondria was correlated to RFI phenotype. Therefore attempts will be made to develop a high-throughput assay to measure oxygen uptake or to identify respiratory chain proteins differences that can be used as a marker for RFI phenotype. Furthermore, the Alabama and Idaho Experiment Stations will collaborate in understanding environmental interactions with these biological drivers. This collaboration will provide cattle raised in cool temperate and subtropical environments to investigate potential environmental influences on these key biological drivers. 3. To determine the relationships between RFI and efficiency of feed utilization in stocker, feedlot and cow-calf sectors. While a number of studies have demonstrated that genetic variation in RFI exists in growing cattle, limited data are currently available establishing the linkage between efficiency in growing vs finishing calves, or between growing calves or mature cows. Moreover, few studies have examined the effects of dietary energy concentration (roughage vs grain-based diets), or common management practices on genetic variation in RFI. Studies under this objective will determine relationships between RFI as defined by a standard post-weaning test, and efficiency at other animal life-stages, that are typically managed under different management regimes. Scientists at the Illinois Experiment Station will compare the RFI ranking of steers in a typical growing-finishing program with herdmate heifers from the same sires fed an all forage diet. The reproductive and performance data of these heifers as cows will be monitored for at least three years. Furthermore, the Missouri and Texas Experiment Stations have developed herds of cattle (Hereford, Simmental x Angus, and Brahma x Hereford) that are being divergently selected for RFI. Establishment of these herds will allow the study of RFI effect at different life-stages of the cow herd. The females in these herds will have RFI measured by a standardized test protocol (concentrate-based diet) initiated at weaning. Immediately after this test RFI will be reevaluated using a forage-based diet. These animals will then be reevaluated for RFI at 18 month intervals. Offspring generated from divergent selection for RFI will also be evaluated for RFI. Steers will be phenotyped using a concentrate-based diet and heifers will be phenotyped using a forage-based diet. These data will be used to determine the potential advantage in efficiency that can be gained via selection for RFI. The West Virginia Experiment Station will continue to phenotype purebred Angus and crossbred cowherds using a forage-based diet at multiple times in the cows production cycle. Replacement females as well as original matriarchs and additional Angus and crossbred matriarchs will be randomly bred to purebred Angus bulls selected and purchased from the West Virginia Young Sire Evaluation Program. These bulls will be performance and RFI phenotype tested on a predominant forage-fiber-based diet. Bulls will be used in pairs with similar production traits but divergent RFI values. Calves from these matings will continue to be RFI tested at weaning with subsequent small group production evaluation occurring at various production stages. Idaho is evaluating progeny of bulls in a similar manner. At the Alabama, Idaho and West Virginia Experiment Stations, we will study populations of steers tested in a standard post-weaning RFI test compared to the same populations evaluated for feed efficiency in the finishing phase. Additionally, various methods measuring forage intake (eg., fecal markers, quantification of forage mass and quality) will be employed by the Missouri and Texas Experiment Stations to determine if calves previously identified as having divergent RFI based on standard post-weaning RFI measurements, also differ in efficiency of feed utilization whiling grazing forage. Rank correlations will be determined and the relationship between the two phases determined for a range of beef cattle of several genotypes. The diversity of environments offered by the participating experiment stations will also allow the investigation of the interactions between environment and life-stage feed efficiency. 4. To examine the effects of selection for RFI on other economically relevant traits. Although RFI is thought to be independent of most other economically important production traits, including reproductive traits and product quality traits, development of RFI will require long-term monitoring for undesirable associations between traits. To date, one notable association is the weak correlation between RFI and composition of gain; with animals superior for RFI being slightly leaner. In addition, because differences in RFI appear to be related to variation in maintenance energy requirement, which in turn is related to rates of body protein turnover; this observation has implications in terms of ultimate meat quality, because animals with lower rates of protein turnover (and therefore more energy efficient) would tend to have slower rates of meat ageing and tenderization. Under this objective, the California, Idaho, Illinois, Missouri, Nevada and Texas Experiment Stations will work collaboratively to study RFI interactions with both production- and product quality-related traits, especially objective measures of muscling, fatness and intramuscular fat composition. Steers that have been RFI evaluated in a standard post-weaning RFI test will be grown to finish and slaughtered. Carcass and meat quality traits will be determined using standard methods. Relationships between RFI and finishing body composition and measures of product quality of selected muscles including Warner-Bratzler Shear force and taste panel evaluation will be conducted. The project will also build additional synergy under this objective. For example, Idaho Experiment Station will also evaluate product quality on RFI-tested steers characterized under sub-projects being conducted at the Illinois and Missouri Experiment Stations. Additionally, the Alabama, Texas and West Virginia Experiment Stations will examine the interactions between RFI and reproductive efficiency traits in females (e.g., age at first puberty, conception rates) and males (e.g., age at puberty, semen quality). 5. To develop EPDs, multi-trait selection indices and decision-support tools to facilitate selection for improved feed efficiency in beef cattle. Studies under this objective will develop quantitative tools for the evaluation of RFI and its implementation into industry. A major objective of this project will be the integration of data from populations of beef cattle in the development of high accuracy EPDs for RFI and other production traits. Advanced concepts in mathematical modeling of RFI will also be studied under this objective. Specifically, the California and Texas Experiment Stations will evaluate and re-parameterize existing mechanistic nutrition models to explain more of the individual variation in nutrient requirements and intake to facilitate selection programs to identify animals that have divergent differences in efficiency of feed utilization. Data from experiments conducted by participating Experiment Stations will be used to test and improve existing simulation models of cattle growth and body composition. Models will be modified by identifying and quantifying model parameters that reflect efficiency differences between animals, allowing estimation of system effects of selection or feeding animals of different efficiencies. Modeling analyses will also serve to evaluate hypotheses and extend interpretation of results regarding RFI, and also as a tool for extending knowledge regarding RFI to the beef industry and the public at large. As the multi-state project database incorporating phenotypic and genotypic information is developed, new iterations of performance models will be developed to interface with this database. This will enable improvement of the existing models as well as development of decision-aid tools to maximize application of those data by industry. 6. To develop producer educational programs to enhance technology adoption by the beef industry. Faculty participating in this multi-state project have research, teaching and extension appointments. Outreach will be a strong thrust of our multi-state efforts. Participation of members in a BIF National Standards sub-committee for development of feed efficiency testing protocols and interaction with state cattle associations and national breed societies will contribute to the integrative character of the project. The following Experiment Stations are either presently active in the roles described above or will benefit from the establishment of this multi-state project, that will facilitate broader interaction of extension faculty bringing national impact to our outreach efforts: Alabama, California, Idaho, Missouri and Nevada.

Measurement of Progress and Results

Outputs

• Research supported by this project will result in training of new researchers equipped to integrate applied feed efficiency research with molecular and cell biology methods to study genes, specific pathways and regulatory factors that contribute to variation in RFI.
• Increased knowledge of the role of specific genes and gene variants in regulating feed efficiency in beef cattle.
• Increased integration and mechanisms for sharing of information between the scientific community engaged in the study of RFI and other measures of feed efficiency, the seed-stock industry, cow-calf producers, feed-yards, and national and state beef cattle associations.

Outcomes or Projected Impacts

• Publications will be the primary tangible result expected from the project.
• Extensions publications derived from the primary scientific publications and other sources such as the project database will provide an important link that will lead to increased industry adoption nation-wide, and improved feed efficiency in beef cattle.
• The Committee will sponsor a Symposium on Molecular Mechanisms underlying RFI. This symposium will provide a mechanism to convey new research information and will increase the visibility of the project.
• Increased understanding of the role of growth factors and cell signaling pathways in regulating metabolic processes may lead to molecular- and cellular biology-based strategies to aid in selection of more feed-efficient beef cattle which will benefit both producers and consumers.
• Elucidation of specific genetic variation including SNPs responsible for variation in feed efficiency may provide information necessary to utilize genetic selection or molecular- or cell biology-based methods to manipulate metabolic pathways in growing beef cattle. For example, it may be possible to reduce protein degradation in growing muscle, which appears to be one of the mechanisms underpinning variation in RFI. This will allow more rapid muscle growth without increasing energy requirements.
• Outcome/Impact 6. Gene expression studies may also lead to identification of genes that may be used to produce transgenic animals that grow more efficiently. Additionally, because this project combines the skills of physiologists, nutritionists, muscle biologists, molecular biologists, geneticists, and outreach specialists, collaboration between committee members should result in integration of knowledge from the whole animal level to the level of the gene and/or cell in the elucidation of mechanisms that contribute to whole animal variation in feed efficiency. Outcome/Impact 7. Interaction of the committee with the seed-stock industry will enable development of multi-breed EPDs for RFI.

Milestones

(2008): and 2012: Sponsor a symposium on Mechanisms underlying variation in RFI at ASAS/ADSA National Meeting. This will allow us to convey research findings to interested individuals in these organizations.

(2011): Sponsor a symposium at the annual meeting of the Beef Improvement Federation to (1) Overview the implementation of RFI and the continuing need for adherence to national standards for RFI testing. (2) To report on the development of indicator physiological traits and gene markers as potential indicators of RFI. This will provide an important interface for science and industry to review current issues in development of RFI and adoption by industry.

Projected Participation

View Appendix E: Participation

Outreach Plan

Project participants have a history of information sharing activities, cooperation, and productivity. Many of the project scientists have been involved in similar areas previously (e.g. WCC-92), some for decades. Their expertise and productivity are well documented by previous publications.

Several of the scientists involved in this project have Extension appointments. This will enhance the dissemination of research results to the general public through presentations and popular publications. There are no artificial boundaries where the research component waits for the outreach function to do something with the information generated from project efforts. It is the intention of the technical committee that new questions and information should flow freely between the laboratory and industry to benefit the ultimate consumer. Most project scientists interact with outreach personnel at three respective institutions and at regional and national levels. Many of the aforementioned "Outcomes or Projected Impacts" lend themselves to outreach education activities. Various media can be used to educate producers, processor, policy makers, and consumers.

It is intended that preparation of peer reviewed publications, presentations at professional meetings, and other means of disseminating project results to professional audiences be part of the ongoing project effort. This group also will work collaboratively with industry and government leaders to provide additional insight into solutions for many of the emerging challenges facing the livestock and meat industries. This will be accomplished by inviting these individuals to annual meetings and requesting their input into research directions for the future and their critique of ongoing research. When appropriate, published proceedings, or other published work will be released to the appropriate audiences.

Further, we will extend our findings about RFI via models that will be integrated in producer software and outreach activities, such as beef performance projection and ration formulation computer programs. Thus the economics of use of animals with different RFI can be quantified. It is anticipated that utilization of these published results will lead to improved efficiency of lean meat production in domestic livestock and poultry. Additionally, in 2008 and 2012 the committee will organize symposia on Molecular Mechanisms that underlie variation in RFI for the joint annual meeting of ASAS and ADSA that will convey recent research findings to the members of these organizations.

Organization/Governance

The Technical Committee will consist of at least one representative from each participating unit, appointed as described in the Manual for Cooperative Regional Research, with one representative from each unit designated as the voting member. The Western Regional Association of Directors will appoint one Director to serve as Administrative Advisor and a representative of the USDA/CSREES will also serve as an Advisor; both will be ex officio member of this committee. The Technical Committee will elect a Chair and a Secretary to serve for a period of one year, and these officers will continue to be voting members. In succeeding years, the Secretary will become Chair, and only a new Secretary will be elected. The Chair, the Secretary, the immediate Past Chair and the Administrative Advisor will serve as the Executive Committee, and they will have the authority to act on behalf of the Technical Committee during the periods between meetings.

The Chair, with approval of the Administrative Advisor, will call yearly meetings of the Technical Committee and interim meetings of the Executive Committee if needed. A report of research results from each unit will be presented orally and in writing at the Technical Committee meetings. The written report should include a list of publications resulting from research related to the project for the year. Reports will be critically reviewed by the Technical Committee and recommendations will be made for future research and coordination of research between units to maximize attainment of the Objectives. The Secretary will prepare minutes and an Annual Report for distribution to Technical Committee members, Directors and Department Chairs of participating State Agricultural Experiment Stations and USDA Laboratories, and the Regional Research Office, CSREES. Because submission of a yearly progress report is essential to assess progress, ensure participation, and prepare the Annual Report, any unit that does not submit a written progress report for two consecutive years will be considered not to be participating and will be dropped from the project.

Literature Cited

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2. Arthur P, Herd R, Archer J, and Exton S. Towards Feed Efficiency EBVs. BREEDPLAN Expo, 1997.

3. Arthur PF, Archer JA, and Herd RM. Feed intake and efficiency in beef cattle: overview of recent Australian research and challenges for the future. Australian Journal of Experimental Agriculture 44: 361-369, 2004.

4. Arthur PF, Archer JA, Johnston DJ, Herd RM, Richardson EC, and Parnell PF. Genetic and phenotypic variance and covariance components for feed intake, feed efficiency, and other postweaning traits in Angus cattle. Journal of Animal Science 79: 2805-2811, 2001.

5. Baker SD, Szasz JI, Klein TA, Kuber PS, Hunt CW, Glaze JB, Jr., Falk D, Richard R, Miller JC, Battaglia RA, and Hill RA. Residual feed intake of purebred Angus steers: effects on meat quality and palatability. J Anim Sci 84: 938-945, 2006.

6. Basarab JA, Price MA, Aalhus JL, Okine EK, Snelling WM, and Lyle KL. Residual feed intake and body composition in young growing cattle. Canadian Journal of Animal Science 83: 189-204, 2003.

7. Brown EG, Carstens GE, Fox JT, Curley KO, Bryan TM, Slay LJ, Welsh TH, Randel RD, Holloway JW, and Keisler DH. Physiological indicators of performance and feed efficiency traits in growing steers and bulls. . J Anim Sci 82(Suppl. 2): 54, 2004.

8. Campbell L, Ahola JK, Szasz JI, Skow TA, Hunt CW, Glaze JB, Jr., and Hill RA. Relationship between residual feed intake and meat quality in steer progeny of divergent intramuscular fat EPD angus bulls. Western Section Meeting of the American Society of Animal Science., Moscow, ID., 2007.

9. Carstens G, Hill R, Welsh T, Davis M, Pollak J, and Bullock D. National Beef Cattle Evaluation Consortium Position Paper on the Use of Insulin-like Growth Factor I (IGF-I) as an Indicator Trait in a Genetic Evaluation for Feed Efficiency., 2007.

10. Carstens GE, Theis CM, White MB, Welsh TH, Jr., Warrington BG, Randel RD, Forbes TDA, Lippke H, Greene LW, and Lunt DK. Residual feed intake in beef steers: I. Correlations with performance traits and ultrasound measures of body composition. Proceedings of the Western Section Meeting, American Society of Animal Science 53: 552-555, 2002.

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12. Exton SC and Archer JA. Testing procedures to enable selection for improved net feed conversion efficiency in beef cattle. Breeding ... responding to client needs. Association for the Advancement of Animal Breeding and Genetics. Proceedings of the Twelfth Conference, Dubbo, NSW, Australia 6th-10th April 1997: Part 1., 1997, p. 251-259.

13. Exton SC, Herd RM, and Arthur PF. Identifying bulls superior for net feed intake, intramuscular fat and subcutaneous fat. Animal Production in Australia 25: 57-60, 2004.

14. Herd RM, Archer JA, and Arthur PF. Selection for low postweaning residual feed intake improves feed efficiency of steers in the feedlot. 50 years of DNA: Proceedings of the Fifteenth Conference, Association for the Advancement of Animal Breeding and Genetics, Melbourne, Australia, 7-11 July 2003, 2003, p. 310-313.

15. Herd RM and Bishop SC. Genetic variation in residual feed intake and its association with other production traits in British Hereford cattle. Livestock Production Science 63: 111-119, 2000.

16. Hill RA and Herd RM. Variation in the endocrine system which might affect feed efficiency. In: Feed Efficiency in Beef Cattle (Proceedings of the Feed Efficiency Workshop), edited by Archer JA, Herd RM and Arthur PF. Armidale: Cooperative Research Centre for Cattle and Beef Quality., 2001, p. 46-50.

17. Kolath WH, Kerley MS, Golden JW, and Keisler DH. The relationship between mitochondrial function and residual feed intake in Angus steers. J Anim Sci 84: 861-865, 2006.

18. Kolath WH, Kerley MS, Golden JW, Shahid SA, and Johnson GS. The relationships among mitochondrial uncoupling protein 2 and 3 expression, mitochondrial deoxyribonucleic acid single nucleotide polymorphisms, and residual feed intake in Angus steers. J Anim Sci 84: 1761-1766, 2006.

19. McDonagh MB, Herd RM, Richardson EC, Oddy VH, Archer JA, and Arthur PF. Meat quality and the calpain system of feedlot steers following a single generation of divergent selection for residual feed intake. Australian Journal of Experimental Agriculture 41: 1013-1021, 2001.

20. Moore KL, Johnston DJ, Herd RM, and Graser HU. Genetic and non-genetic effects on plasma insulin-like growth factor-1 (IGF-I) concentration and production traits in Angus cattle. 50 years of DNA: Proceedings of the Fifteenth Conference, Association for the Advancement of Animal Breeding and Genetics, Melbourne, Australia, 7-11 July 2003, 2003, p. 222-226.

21. Nkrumah JD, Basarab JA, Price MA, Okine EK, Ammoura A, Guercio S, Hansen C, Li C, Benkel B, Murdoch B, and Moore SS. Different measures of energetic efficiency and their phenotypic relationships with growth, feed intake, and ultrasound and carcass merit in hybrid cattle. J Anim Sci 82: 2451-2459, 2004.

22. Nkrumah JD, Li C, Basarab JB, Guercio S, Meng Y, Murdoch B, Hansen C, and Moore SS. Association of a single nucleotide polymorphism in the bovine leptin gene with feed intake, feed efficiency, growth, feeding behaviour, carcass quality and body composition. Canadian Journal of Animal Science 84: 211-219, 2004.

23. Nkrumah JD, Li C, Yu J, Hansen C, Keisler DH, and Moore SS. Polymorphisms in the bovine leptin promoter associated with serum leptin concentration, growth, feed intake, feeding behavior, and measures of carcass merit. J Anim Sci 83: 20-28, 2005.

24. Nkrumah JD, Okine EK, Mathison GW, Schmid K, Li C, Basarab JA, Price MA, Wang Z, and Moore SS. Relationships of feedlot feed efficiency, performance, and feeding behavior with metabolic rate, methane production, and energy partitioning in beef cattle. J Anim Sci 84: 145-153, 2006.

25. Rauw WM. Physiological consequences of selection for increased performance. Proceedings of the Association for the Advancement of Animal Breeding and Genetics., Armidale, Australia. , 2007, p. 240-247.

26. Richardson EC and Herd RM. Biological basis for variation in residual feed intake in beef cattle. 2. Synthesis of results following divergent selection. Australian Journal of Experimental Agriculture 44: 431-440, 2004.

27. Richardson EC, Herd RM, Oddy VH, Thompson JM, Archer JA, and Arthur PF. Body composition and implications for heat production of Angus steer progeny of parents selected for and against residual feed intake. Australian Journal of Experimental Agriculture 41: 1065-1072, 2001.

28. Robinson DL, Oddy VH, Dicker RW, and McPhee MJ. Post-weaning growth of cattle in northern New South Wales. 3. Carry- over effects on finishing, carcass characteristics and intramuscular fat. Australian Journal of Experimental Agriculture 41: 1041-1049, 2001.

Attachments

Land Grant Participating States/Institutions

AL, CA, CO, FL, ID, IL, KY, MN, MO, MS, MT, NC, NE, NV, OH, OK, SD, TX, UT, WV

Non Land Grant Participating States/Institutions

Australia, Mississippi State University