National Program 101            Food Animal Production

National Program Annual Report:  FY 2005 

• Introduction
• Reproductive Efficiency
• Conservation, Characterization, and Use of Genetic Resources
• Pre-Harvest Product Quality
• Genetic Improvement
• Genomic Tools
• Growth and Development
• Nutrient Intake and Utilization
• Integrated Systems

Introduction

The food animal production national program is charged with conducting cutting edge research to contribute to increased efficiency and sustainability of production of beef and dairy cattle, poultry, swine, and sheep.  Research efforts in the animal sciences over the past century have had dramatic impacts on animal agriculture both in terms of improved biological and economic efficiency of production and in terms of quantity, quality, and safety of animal products.  Many major challenges remain, however, requiring the dedicated focus of long-term research teams, particularly in the areas of reproductive longevity and animal well-being, adaptability to production environments, product quality, reduction of feed and energy inputs, enhancements in nutrient retention, and reduction of negative environmental impacts.

The program experienced continued success in 2005.  In total, 97 full-time scientists working at 18 locations across the U.S. were actively engaged in 42 research projects in the program.  Research projects in this program area were approved through the ARS Office of Scientific Quality Review in 2002, making this the third year of implementation of these five-year project efforts.

During the past year, program increases were appropriated for forage animal pasture research ($108,000 to Lexington, KY), bovine genetics ($270,000 to Beltsville, MD), dairy forage research ($510,000 to Madison, WI), beef cattle feed efficiency genomics ($315,000 to Clay Center, NE), and beef cattle rumen metagenomics ($135,000 to Miles City, MT) bringing the total appropriations in the national program to over $41M.  Additionally, funds were appropriated for development of new facilities in the program at Lexington, KY ($4M), Marshfield, WI ($8M), and Bozeman, MT ($4M).

Several new permanent scientists were welcomed to the program during 2005 including:  Wayne Coblentz (Madison, WI); Robert Li (Beltsville, MD); Ge Liu (Beltsville, MD); Corey Moffett (Dubois, ID); and Joseph Purswell (Starkville, MS).

Scientists retiring from the agency in the past year include Ron Christenson and Roger Stone from the U.S. Meat Animal Research Center (MARC) and Rex Powell from the Beltsville Agricultural Research Center (BARC).  All three of these scientists leave a long legacy of productive research careers and important scientific contributions in the fields of reproductive physiology, animal molecular genetics and genomics, and dairy cattle quantitative genetics, respectively.

The ARS animal production research community was saddened by the deaths of three members of its ranks in the past year.  Keith Gregory (retired) and J. T. Yen, both from the US MARC, and Ray Woodward (retired) from the Fort Keogh Livestock and Range Research Lab will all be sorely missed.

Ronnie Green served as the national program leader for the program in 2005 with invaluable co-lead responsibilities provided by Lewis Smith.  Contributions to the national program were also provided by program team members Evert Byington, Cyril Gay, and Robert Heckert. 

Leadership changes in 2005 included the naming of Steven Kappes as the Deputy Administrator for the Animal Production and Protection area of the National Program Staff.  Larry Cundiff served as acting Center Director of the US MARC during the year until Mohammad Koohmaraie was named to that position.  Jeff Vallet assumed the position of Research Leader at MARC and Kreg Leymaster and Tommy Wheeler were named to acting Research Leader positions for the Reproduction, Genetics and Breeding, and Meats Research Units, respectively.  Dave Guthrie was named acting Research Leader for the Biotechnology and Germplasm Lab at BARC.

Several scientists in the national program were recognized with prominent awards, including:

Anthony Capuco, Beltsville, MD – Physiology Award, American Dairy Science Association

Bob Wall, Beltsville, MD – Scientist of the Year, Beltsville Area, USDA/ARS

Ron Christenson (retired), Clay Center, NE – Fellow Award, American Society of Animal Science

Andy Cole, Bushland, TX – Animal Management Award, American Society of Animal Science

Mike MacNeil, Miles City, MT – Continuing Service Award, US Beef Improvement Federation

Rex Powell (retired), Beltsville, MD – Fellow Award, American Dairy Science Association

James Russell, Ithaca, NY – AFIA Feed Industry Award, American Society of Animal Science

James Russell, Ithaca, NY – Scientist of the Year, North Atlantic Area, USDA/ARS

Larry Satter (retired), Madison, WI  -- Land O’Lakes Award, American Dairy Science Association

Bob Short (retired), Miles City, MT – Fellow Award, American Society of Animal Science

Dale Van Vleck, Clay Center, NE – Morrison Award, American Society of Animal Science

The high quality and impact of research conducted in the program was further evidenced by the fact that scientists delivered 77 invited presentations at international and national symposia during the past year.   During the year, 2 new CRADAs were established and 3 new patents were filed by researchers in the program.  Additionally, a total of $2.2M in extramural grant award funding was received by scientists in the program, supported in many cases by cooperative research programs with partners at land grant universities. Administrator’s Postdoctoral Awards were granted to Hans Cheng (East Lansing, MI) and Curt Van Tassell (Beltsville, MD).

Partnerships with land grant and 1890s universities continued to be very important to the success of the national program in 2004.  These partnerships are greatly appreciated and take on a variety of forms including work with those in the states of Arkansas, Colorado, Florida, Georgia, Idaho, Illinois, Iowa, Kentucky, Maryland, Michigan, Minnesota, Mississippi,  Montana, Nebraska, New York, Virginia, West Virginia, and Wisconsin.

A number of meetings and workshops were sponsored by this national program in the past year including:  National Beef Cattle Evaluation Consortium Conference on Genetics of Adaptability (Kansas City, MO); ADSA DISCOVER Conference on Transition Dairy Cows (Nashville, IN); ADSA DISCOVER Conference on Animal Germ Plasm (Cheyenne, WY); Bovine Genome II (Houston, TX); and Western Section of American Society of Animal Science Beef Symposium (Las Cruces, NM).

This is a particularly exciting time for this research and program area.  In 2005, an improved draft assembly of the chicken genome was released (7-fold coverage) along with identification of over 3M single nucleotide polymorphisms (SNP), the bovine genome sequence stood at 6-fold coverage and the bovine HapMap project was well underway, and the international swine genome sequencing consortium launched the swine genome project at the Sanger Institute in the U.K.  These efforts have required creative approaches to funding and the leveraging of resources across federal agencies, international governments, and private industry and their fruits open a new frontier for research in food animal production.  In the coming years, research scientists will be able to begin to strategically tackle important problems in previously difficult areas including efficiency of nutrient use, animal adaptation to production environments, stress physiology, and genetic resistance to disease using this new genomics infrastructure.

Follow up to the 2004 USDA Animal Genomics Workshop proceeded during the past year.  Recommendations from the workshop have been summarized in a comprehensive report (posted on this same web-site) and are being published in Animal Genetics.  One of the key recommendations emanating from the workshop was that USDA should develop a long-term plan for animal genomics research as has been successfully been done for human health (National Institutes of Health Roadmap) and energy (Department of Energy Genomes to Life).  The development of this plan was initiated in 2005 and will be completed in the coming fiscal year.

Planning for the next 5-year cycle of the national program commenced during 2005.  A retrospective assessment panel was appointed and documentation was prepared for their review to be held in February 2006.  Plans were developed for the next Food Animal Production Stakeholder Workshop, to be held in April 10-12, 2006 in Kansas City, MO.  Input from this workshop will be used to form the 2007-2012 national program action plan that will guide the development of the program’s next 5-year projects.  Additionally, the decision was made to merge the current Food Animal Production (NP 101) and Animal Well-Being and Stress Control Systems (NP 105) programs beginning with the next 5-year projects that will be implemented in July of 2007.  Concordantly, the assessment and workshop activities planned for 2006 will be conducted jointly for the two national programs. 

The following sections of the report summarize high impact research results addressing the eight components in the current national program action plan.

Reproductive Efficiency

Sorting out fetal survival and uterine capacity in swine.  Selection for increased reproductive rate is a primary driver of production efficiency in the swine industry.  It has been suggested that the ability of swine fetuses to survive within a crowded intrauterine environment may be related to the ability to control nutrient distribution among various fetal organs. Researchers at the ARS U.S. Meat Animal Research Center, Clay Center, Nebraska determined the effect of selection for uterine capacity and ovulation rate on fetal weights and fetal brain, heart, liver and spleen weights on days 45, 65, 85 and 105 of gestation. Results indicated that selection for ovulation rate suppressed fetal weights, and fetal liver and heart weights, presumably due to the increased intrauterine crowding in this line caused by the increased ovulation rate. No differences were found from selection for uterine capacity. Examination of the relationships between fetal organ weights and fetal weights on the different days of gestation clearly demonstrated the ability of the fetus to shunt nutrient supplies to various organs, so called "organ sparing" effects. The "brain sparing" effect increased and a "heart sparing" effect decreased significantly with advancing gestation. A "spleen sparing" effect was present throughout gestation. A more complete understanding of the mechanisms involved in these effects could allow manipulation of nutrient use within the fetus, resulting in improved fetal survival and litter size.  Additionally, research has demonstrated that the critical time when line differences in fetal survival are expressed is between 25 and 45 days of gestation.  These results will facilitate gene expression profiling to identify causative genes responsible for these differences.

Novel measurements of swine sperm physiology using flow cytometry.  Boar sperm that have been subjected to long-term low temperature liquid storage or freeze-thawing are less fertile after artificial insemination than freshly collected sperm. Two key physiological processes must occur in order for the sperm cell to be functionally fertile, capacitation and release of enzymes from the acrosome.  However, low temperature liquid storage and cryopreservation are thought to prematurely increase lipid fluidity in the plasma membrane (an early sign of capacitation) and decrease integrity of the acrosome rendering sperm less capable to survive in the reproductive tract of the female and making them less capable of fertilizing eggs. ARS scientists at Beltsville, Maryland have found that long-term storage and freeze-thawing did not prematurely increase capacitation or decrease acrosome integrity in viable sperm as previously suggested. However, compared to fresh semen, the ability of sperm to undergo capacitation after specific lab treatment was greatly decreased by storage and freeze-thawing and responses varied among individual boars. Future work is addressing the differences among boars to determine if these differences are correlated with fertility.

Conservation, Characterization, and Use of Genetic Resources

Genetic security of animal Germplasm enhanced. The security of U.S. animal genetic resources was significantly enhanced in the past year. Samples in the ARS National Animal Germ Plasm collection at Fort Collins, CO increased 52% and the number of breeds or lines increased 63%. In addition, a total of 19 livestock, poultry and fish populations met minimum collection requirements considered to be secure. These achievements were made possible by the contributions of 170 different livestock producers, public institutions and companies.  Conservation of germplasm resources will allow continued ability to maintain important levels of genetic variability in the nation’s livestock, poultry, and fish populations.

Pre-Harvest Product Quality

Validation and technology transfer of the MARC beef tenderness prediction system.  Previously, the only method to accurately predict whether or not a beef carcass would produce tender or tough steaks was to remove a steak from the carcass and evaluate tenderness mechanically, resulting in a high cost from of product devaluation.  Thus, the beef industry has sought development of a non-invasive method for beef tenderness prediction.  Scientists at the U.S. Meat Animal Research Center, Clay Center, Nebraska produced a non-invasive beef tenderness prediction system that was validated in several packing plants representing a broad sampling of cattle types and processing scenarios in collaboration with the National Cattlemen’s Beef Association and five beef companies.  Based on the current level of interest in adoption of this technology, it is expected to have an annual multi-million dollar impact on the beef industry and its consumers.

Evaluated the impact of dietary perchlorate in dairy cows.  Perchlorate is a goitrogenic anion that competitively inhibits the sodium iodide transporter and has been detected in forages and in commercial milk throughout the U.S.  The fate of perchlorate and its effect on animal health were studied in lactating cows, ruminally infused with perchlorate for five weeks, by ARS scientists at Beltsville, Maryland.  Milk perchlorate levels were highly correlated with perchlorate intake, but milk iodine was unaffected and there were no demonstrable health effects.  Results demonstrated that up to 80% of dietary perchlorate was metabolized, most likely in the rumen, which would provide cattle with a degree of refractoriness to perchlorate.  These results are important for assessing environmental impact on perchlorate concentrations in milk and its relevance to human health and provide important data for agencies assessing health risks of environmental perchlorate.

Genetic Improvement

Genetic evaluations for calving ease are implemented for dairy cattle.  Calving difficulty (dystocia) has a major economic impact on productivity and profitability of dairy production. Dairy producers are increasingly interested in crossbreeding as a tool to improve calving ease, health, fertility, and longevity, and Brown Swiss bulls appear to produce daughters that give birth more easily than those of Holstein bulls. ARS scientists at Beltsville, Maryland implemented national genetic evaluations for Brown Swiss calving ease that will be provided quarterly along with Holstein calving-ease evaluations to the National Association of Animal Breeders for distribution to the U.S. dairy industry. National genetic evaluations for calving ease provide the dairy industry with information to reduce losses from a high incidence of difficult births.

Gene mutation identified affecting milk protein percentage in dairy cattle.  Percentage of milk made up by the protein fraction is of critical importance to the dairy industry (eg. for cheese production).  Scientists in the ARS Bovine Functional Genomics Laboratory at Beltsville, Maryland, in collaboration with colleagues at the University of Missouri-Columbia, have identified a mutation in the osteopontin gene promoter region, which is a candidate quantitative trait nucleotide underlying a previously identified quantitative trait locus for protein percentage located on bovine chromosome 6.  This marker was found to be in complete linkage disequilibrium across multiple sire families making it highly useful for genetic selection programs.  A provisional patent application for using this polymorphism information in marker-assisted selection programs was submitted and has been licensed by a multi-national pharmaceutical company that is currently validating its effectiveness in selection to improve this trait.

DNA marker toolbox for beef tenderness enhanced.  Inadequate tenderness is the principal cause of consumer dissatisfaction.  Previously, markers for two genes associated with differences in beef tenderness (u-calpain and calpastatin) have been proposed to improve meat quality.  It was not known if the effects of these two commercially available gene markers would add together or if the effect of one gene marker would be masked by the other.  ARS researchers at Clay Center, Nebraska tested these markers in two diverse populations of cattle (both Bos indicus and Bos taurus) and crosses between these populations.  Regardless of the population, the effects of the gene markers on tenderness were nearly independent indicating that both markers can be used to genetically improve tenderness.  Additionally, a new u-calpain marker with predictive merit for genetic propensity to produce meat with improved tenderness was developed and released to industry that allows use of the test across all breed populations.  This marker is impacting breeding decisions and bull prices and is provided to industry through four commercial services.

Insulin-like growth factor identified as a candidate gene for genetic selection in chickens.

Molecular selection on individual genes is a promising method to improve economically important traits in chickens.  ARS scientists at Beltsville, Maryland developed a resource population to study the genetics of growth, body composition, skeletal integrity, and metabolism traits with insulin-like growth factor-I (IGF-I) selected for study as a biological and positional candidate gene.  A single nucleotide polymorphism was identified in the resource population in the IGF-I promoter region and was determined to show significant associations with performance traits.  Several beneficial effects associated with variation in the polymorphism, including improved growth, increased breast muscle weight, decreased abdominal fat, and enhanced skeletal integrity; indicate the presence of one or more nearby genes controlling biologically diverse and economically important traits in chickens.

Genomic Tools

The Bovine Genome Project steams forward.   A major international project has been underway since 2003 to develop an annotated DNA sequence assembly of the bovine genome.  This project has been led by the research team at Baylor College of Medicine’s Human Genome Sequencing Center (Houston, Texas).  An international consortium of researchers has been working alongside of the Baylor team to develop and carry out this project, including several key ARS contributions.  1) Sequencing animal is inbred Hereford female.  The sequencing effort is being carried out on the DNA of an inbred Hereford female from the long-term Line 1 inbreeding and selection experiment at the ARS Fort Keogh Range and Livestock Lab at Miles City, Montana.  2) ARS researchers at Clay Center, NE have developed a scaffold onto which to assemble the bovine genomic sequence.  23 million individual sequences (6.2-fold coverage) of the bovine genome had been produced at Baylor as of June 2005 and subsequently placed into 102,467 assembled sequences.  These assembled sequences can now be positioned onto individual bovine chromosomes using the new scaffold or map permitting the association of sequence differences with economically important traits such as feed efficiency, meat quality, viability, disease resistance and reproductive rate.  Construction of the scaffold was an international collaboration including ARS, University of Illinois, Texas A&M University, and international collaborators in the U.K., France, Japan, New Zealand, Australia, Brazil and Canada.  The scaffold was used to estimate that the assembled sequences cover ~95% of the bovine genome.  3) Multi-breed DNA panel developed for building of the bovine haplotype map.  One of the major thrusts of the bovine genome project is to develop a large pool of single nucleotide polymorphisms (SNP) for use in evaluating genetic diversity and in development of gene-based genetic improvement programs.  ARS scientists from Clay Center, Nebraska and Beltsville, Maryland have provided the leadership for the development of resource populations of Holstein, Jersey, Angus, Hereford, Limousin, and Red Angus animals to develop and validate more than 20,000 SNP.  Combined with panels of animals representing an additional 12 breeds from around the world, this will ultimately lead to a haplotype map of the bovine genome.  4)  DNA resources provided for development of a large panel of full-length complementary DNAs (cDNAs).  ARS scientists at Miles City, Montana collected tissues from animals related to L1 Dominette 01449, the base DNA source for the bovine genome sequence.  A wide range of tissues were collected and are being used for construction and sequencing of a large number of cDNA libraries in collaboration with Genome Canada and others.  Additionally, ARS scientists at Clay Center completed full clone sequencing for clones predicted to contain the complete protein coding sequence of a gene, annotated the gene for its predicted protein sequence and, where possible, gene function, and deposited the DNA and protein sequences in the public database of sequence information at the NIH National Center for Biological Information (NCBI). The project completed the first 954 bovine sequences to be included in the NCBI “full length insert clone” database, and more than 350 have so far provided the basis for annotated genes in the draft bovine genome.

Improved accuracy of prion genotyping in sheep.  A control panel of sheep DNA was created to increase the accuracy of prion genotyping by research and commercial laboratories. Variation in the prion gene is associated with susceptibility and resistance to scrapie, a neurological disease of sheep that is similar to bovine spongiform encephalopathy (BSE) in cattle. ARS scientists created a control DNA panel from sheep representing each of 15 prion genotypes associated with susceptibility and resistance to scrapie. The control DNA panel is used to detect genotyping errors and to improve the quality of genetic information. This valuable resource is helping producers in the United States and other countries to correctly select for genetic resistance to scrapie and to achieve the industry goal of eradicating the disease from its flocks.

Development of a panel of DNA markers for swine identification. Individual animal identification is critically important for livestock biosecurity.  Until recently, DNA genotyping laboratories did not have access to a set of the most robust swine DNA markers to uniquely identify animals or accurately determine parentage. Single nucleotide polymorphism (SNP) markers are easily typed with automated techniques that do not rely on human interpretation. ARS scientists at Clay Center, Nebraska developed a subset of SNP markers that was typed across a panel of purebred boars, resulting in the identification of 40 suitable markers. This information has been released to 39 different investigators representing scientific and commercial genotyping laboratories around the world. These markers will likely develop the framework of markers used by most commercial genotyping companies to determine individual animal identification in pigs.

Growth and Development

Hormones controlling growth and onset of puberty differentially regulated in swine.  ARS scientists in the Animal Physiology Unit at Athens, Georgia utilized DNA microarray technology to identify 63 brain and 24 pituitary differentially regulated genes during pubertal development in swine. The genes studied control the release of brain hormones which subsequently regulate luteinizing hormone and growth hormone release from the pituitary gland in swine. These pituitary hormones play critical roles in determining growth and onset of puberty. Understanding these interactions is necessary in order to develop new methods to promote maximal growth while enhancing onset of puberty and subsequent reproductive function in the pig, critical components impacting efficiency of swine production.

Functional enzyme pathway regulating feed intake identified in chickens.  Regulation of feed intake and energy balance is critical to profitable poultry production.  AMP-activated protein kinase (AMPK) is an enzyme complex that plays a key role in sensing cellular energy (AMP/ATP) levels, maintaining intracellular energy homeostasis and, on the whole animal level, in regulating energy balance and food intake.  Scientists in the ARS Growth Biology Laboratory at Beltsville, Maryland have identified seven distinct chicken AMPK gene homologues and have studied their expression in different tissues.  The expression of these genes confirmed, for the first time, the existence of a functional AMPK pathway in chickens and indicated that AMPK is likely to be a master cellular energy sensor/regulator.  These findings provide new information related to the regulation of feed intake, energy balance and body weight in chickens at the molecular level.
 

Nutrient Intake and Utilization

Altering lignin synthesis in plants to improve their digestibility for dairy production.  Alfalfa is widely used as a fiber and energy source for dairy cow diets. It is limited, however, by poor digestion of the structural carbohydrates (fiber component) limiting the energy recovered from the plant by the dairy cow. Lignin (the glue that holds fiber together) is completely indigestible itself and as a result of how it is made and incorporated into the fiber, the structural carbohydrates also become less digestible. One approach to solving the problem of poor fiber digestibility is to alter the lignin to decrease its negative impact. Collaborative efforts of the Noble Foundation, Forage Genetics, and the ARS U.S. Dairy Forage Research Center have resulted in alfalfa transgenics that were down-regulated in enzyme C3H, a crucial step of lignin synthesis; and have shown that such plants produced lignin with dramatic changes in composition and structure. Over 60% of the lignin is built from a component that is normally a minor constituent in normal lignin. Because lignin is crucial to the plant for strengthening its fibers and water transport, severe down-regulation of C3H depressed plant growth. However, lesser down-regulation still greatly impacts the lignin structure, but restores plants to normal vigor. Such intermediate plants appear to be more digestible. This process provides a potential approach to improving plant fiber utilization in dairy and beef cattle, sheep, and goats.

Source of protein important for dairy production.  Optimizing the amount of protein formed by the rumen microbes of dairy cows is important because this source provides more than half of the protein actually used by animal.  It is widely believed by dairy nutritionists that non-protein nitrogen (NPN) can replace true protein to meet the nitrogen requirements of the rumen microbes. An experiment was conducted at the ARS U.S. Dairy Forage Research Center, Madison, Wisconsin, with lactating dairy cows to investigate the effect of source of rumen-degraded protein (RDP) on milk production and microbial protein synthesis in the rumen. Diets were composed of alfalfa silage, corn silage, and high-moisture corn (typical feeds used for dairy cows in the U.S.) and contained a range of levels of RDP added from different proportions of soybean meal (a source of true protein) and urea (a source of NPN). As more and more urea replaced soybean meal, there was decreased feed intake, milk yield, and body weight gain. Replacing RDP from soybean meal with that from urea NPN also resulted in increased milk urea N and ammonia in the rumen, but reduced microbial protein formation in the rumen. Farmers benefit from this research by knowing that replacing true protein with NPN will reduce milk production and impair N utilization in lactating dairy cows.

Integrated Systems

Prediction of protein in body weight gain incorporated in to decision support tool for the beef industry.  Decision support tools have become an increasingly important means for producers to comprehensively evaluate biological and economic information to make management decisions.  One such tool is the Decision Evaluator for the Cattle Industry (DECI) developed by ARS since 1994.  A component model to predict the amount of protein in body weight gain was recently developed, tested, evaluated and incorporated into DECI by ARS scientists at Clay Center, Nebraska. Published data on protein gains were used to formulate, parameterize and evaluate a mathematical model that predicted protein gain as a function of body fatness and the amount of lean gain. Protein gain is used to calculate nitrogen retention, and protein gain plus fat gain represents energy retention. This model increased the accuracy of DECI in predicting nitrogen excretion and efficiency of energy utilization, and as a decision support tool, it makes DECI more useful in developing nutrient management plans for beef feedlots.

Matching beef breed type and stocker production system.  Calves from tropically adapted breeds do not perform as well as calves from temperate breeds when used as stocker calves to graze annual cool-season grasses during the winter. Cow herds in the southeastern U.S. are composed of tropically adapted beef breeds that are genetically adapted to tolerate the region's hot and humid climate, but the calves produced on these farms are transported to more temperate climates for growth and development. Post-weaning performance of tropically adapted breeds imported from Africa (Bonsmara) and South America (Romosinuano) were compared to temperate breeds (Charolais, Gelbvieh, Angus and Hereford) by ARS scientists at El Reno, Oklahoma and Brooksville, Florida to determine if these imported beef breeds could be used to obtain the needed genetic tropical adaptation in the cow herd without reducing subsequent winter stocker performance. Tropically adapted breeds gained weight at a slower rate during the winter than other breeds in the experiment when grazed on cool-season grasses. Producers could utilize feed resources more efficiently, if the tropically adapted breeds were lot-fed growing rations during the winter, while the temperate breeds were used to graze cool-season grasses.  These results are being used to formulate recommendations for how these sources of germplasm can be used to improve profitability of sub-tropical beef production in the Gulf coast region of the U.S.