Location: Nutrition Research
Title: USMARC expands feed-efficiency research program Author
Submitted to: Trade Journal Publication
Publication Type: Trade Journal
Publication Acceptance Date: November 30, 2007
Publication Date: January 2, 2008
Citation: Allan, M.F. 2008. USMARC expands feed-efficiency research program. Bottom Line. 10(1):14-15. Technical Abstract: Feed efficiency is not a new topic to the beef industry. Historically, this topic has been revisited by the industry every 10 to 15 years providing some benefit to the producer. The lack of progress in understanding the genetics of feed efficiency stems from the difficulty in trying to accurately measure individual intakes, coupled with extreme costs and beef cattle’s long generation interval. Feed efficiency is difficult to define and needs to be evaluated in the producing female, as well the growing/finishing animal. Heritability of feed efficiency has been estimated to be moderate, with values ranging from .28 to .44. These values indicate that genetic variation among and within beef cattle populations does exist for feed efficiency, making genetic selection possible. The main benefit of understanding the genetics of feed efficiency and developing tools to improve efficiency is reduced production costs. With 70-80% of the total variable costs in beef production being feed costs, the slightest improvement in feed efficiency will have a significant impact in profitability in multiple areas of beef production. Technology has developed to a point that we can better measure, record, analyze, and implement selection for energetic efficiency. The U.S. Meat Animal Research Center (USMARC) in Clay Center, Nebraska, has finished construction and begun using a new feeding facility with 300 head one-time capacity. The feeding system capabilities include the ability to monitor individual daily feed intakes and feeding behavior for animals fed to appetite or at restricted intakes and water intakes. Multiple diets and feeding rates can be fed within each pen that has a capacity of 50 animals. This facility will complement an ongoing comprehensive research program initiated in 2001 to identify phenotypic components contributing to feed efficiency during the postweaning period and determine the relationships among these phenotypes and measures of lifetime productivity for cows. Previous efforts to describe these relationships are inconclusive because quantifying these relationships requires animal populations with known parentage, extensive collection of feed intakes from cattle during the finishing period and from heifers during the development period, and extensive performance data throughout the lifetime of the animals. A multidisciplinary team consisting of ruminant nutritionists, reproductive physiologists, molecular and quantitative geneticists, and production scientists are collecting data to 1) identify traits contributing to feed efficiency in different production segments, 2) determine the genetic variation using both quantitative and genomic technologies, 3) determine the genetic relationship between postweaning feed efficiency and maternal performance, 4) apply genomic tools for discovery of DNA markers for efficiency determining traits, and 5) relate markers associated with feed efficiency in the growing animal and production traits expressed in older producing females. By collecting data on an array of production traits, including DNA samples from a population with known pedigree, conclusive information regarding traits affecting feed efficiency for the postweaning animal through the producing cow will be made available to the beef industry. Seven of the most prominent breeds in the American beef industry (Angus, Hereford, Red Angus, Charolais, Limousin, Simmental, and Gelbvieh) were sampled to create a F1 population of bulls and cows. Planned matings of those F1 cows and F1 bulls provide relatively large half-sib families (about 50 calves per F1 sire). Animals to be genotyped include the straight bred sires, F1 sires and dams, and all progeny from matings of the F1 population. Beginning with the 2003 and continuing through the 2007 calf crop, approximately 265 steer calves received a high energy diet for a 156-day feeding period. Individual animal weekly feed intakes are recorded using Calan head-gate system. Additional phenotypic data being recorded for each steer includes on-test and off-test weights and heights, weights and heights at 28-day intervals during the study, flight scores on test, midway and off-test, and carcass and taste panel data. Additionally, blood samples are taken at the beginning and end of the finishing period for determination of concentrations for specific metabolites for all the steers involved in the feed efficiency test. Heifer contemporaries of the steers are fed a more forage-based diet during the postweaning development period with weekly feed intakes recorded (Calan head-gate system). Data collected during the developmental period from each heifer include 28-day weights, temperament assessments, age at puberty, and blood (determination of concentrations of specific metabolites) and fat tissue samples. The heifers will be retained in the cow herd at USMARC to provide cow production data through four calf crops to evaluate reproductive competence and health, milk yield, and dental and structural soundness. Upon removal from the production herd, mature cows will be individually fed to determine feed efficiency in the mature cow. One of the primary objectives of the steer and female experiments is to develop the tools needed to help create EPDs and markers to be used for marker-assisted selection. For a trait that is extremely difficult to measure in the industry setting, application of genetic markers provides opportunities to improve economics of beef production through the genetic selection for feed efficiency, without measuring feed intake directly. If differences exist between cow efficiency and finishing efficiency, markers would be an excellent way for producers to assure improvement for a desired phase of production. USMARC has begun generating greater than 50,000 DNA marker genotypes for each animal with individual feed intake data, with a goal of developing DNA marker solutions to assist in genetic selection for feed efficiency.