2008 Annual Report 1a.Objectives (from AD-416) The long-term objective of this research is to develop an improved understanding of those traits and genes that are responsible for the ability of cattle to adapt to and withstand the harsh conditions of the subtropical region of the United States. Over the next 5 years we will focus on two objectives: Obj.. 1)Complete the evaluation of the influence of breed and breed-type on cow performance in the subtropics by 1a) Estimate heterosis and breed effects for efficiency and adaptability in cows developed with Romosinuano (tropical Bos taurus), Angus (temperate Bos taurus), and Brahman (tropical Bos indicus) breeds and 1b) Develop and evaluate a tropically-adapted composite targeted for the subtropics, and Obj.. 2)Determine the cascade of physiological responses to chronic stressors responsible for and indicative of reduced animal performance in subtropical environments by 2a) Determine if heat and other stressors elicit a differential immune response in cattle with different tolerance to environmental stressors and 2b) Evaluate QTL markers identified for tolerance to internal parasites in cattle in the subtropics. 1b.Approach (from AD-416) For Obj. 1a) After the opportunity to calve as two-year-olds (born from 2002 through 2005), purebred Romosinuano (R), Brahman (B), and Angus (A) cows (n = 120) and crossbred R-B, B-R, R-A, A-R, B-A, and A-B cows (n = 240) will be bred through their 8th breeding season to produce purebred, F1, and three-breed calves. This mating design and subsequent analyses is appropriate for estimation of heterosis for cow maternal traits, i.e., weight and other size traits of their calves. Reproductive traits evaluated will include pregnancy, calving, and weaning rate. Feed efficiency will be determined on a subset of steer and heifer calves. Heifer calves will be developed as replacements for a subsequent project. For Obj. 1b) Following their 8th breeding season, beginning in 2011, cows will be used in the development of a composite ½ Angus ¼ Romosinuano ¼ Brahman. This will be accomplished by using: R-A, A-R cows and B-A, A-B bulls, and B-A, A-B cows and R-A, A-R bulls. Similar cow and calf traits will be measured as in Obj. 1a. For Obj. 2a) Two experiments will be conducted, the first in environmentally controlled rooms and the second under ambient conditions at STARS. For the first, laboratory analyses will be completed for samples collected from 9 R and 9 A steers following: acclimation to thermal neutral conditions, after animals were subjected to heat stress conditions, and after recovery from heat stress, in response to an an endotoxin challenge. In a second experiment, A, B, and R steers at STARS will be sampled during winter and summer under ambient conditions. Feed intake, rectal temperature, and respiration rate will be collected. For both experiments concentrations of cytokines, acute phase proteins, IGF-I, and growth hormone will be determined. For Obj. 2b) Blood and fecal samples will be obtained from all purebred and crossbred calves prior to weaning. Samples will be sent to ARS-BARC where DNA will be extracted and stored from all calves, and fecal samples will be analyzed for nematode egg counts. The number of eggs per gram of feces (EPG) for each animal will be determined. Estimation of genetic control, i.e., heritability, will be determined from these data. At the same time, data from the purebred Angus calves will be used to evaluate the relationship among the EPG phenotype with QTL markers developed at ARS-BARC. 3.Progress Report For Objective. 1)complete the evaluation of the influence of breed and breed-type on cow performance in the subtropics, and Subobjective 1a) estimate maternal heterosis for traits in cows developed from Romosinuano, Brahman, and Angus; calving and weaning data were collected as proposed. Furthermore, steer calves were sent for back-grounding and finishing to Oklahoma and heifers were sent to north Florida for estimation of feed intake and efficiency, also as proposed. This research contributes to NP-101 Food Animal Production, Component 1: “Understanding, Improving, and Effectively Using Animal Genetic and Genomic Resources” and within Problem Statements to “Identify Functional Genes and Their Interactions (1B)” and “Preserve and Curate Livestock and Poultry Genetic Resources (1C). For Objective. 2)determine the cascade of physiological responses to chronic stressors responsible for and indicative of reduced animal performance in subtropical environments, and Subobjective 2a) determine if heat and other stressors elicit a differential immune response in cattle with different tolerance to environmental stressors, and Experiment 1 (immune response in controlled environment); laboratory analyses from the lipopolysaccharide (LPS) portion of Experiment 1 have been completed and a manuscript has been prepared. Some of the laboratory analyses for the thermoneutral and heat stress portion of Experiment 1 have been conducted and the others are currently being conducted (cooperator laboratories). Data collection for Experiment 2 (immune response in ambient subtropical environment); was completed for the first year (one year in advance). Data were collected for the first and second year for Subobjective 2b) Evaluate QTL markers identified for tolerance to internal parasites in cattle in the subtropics. Some laboratory analyses of estimates of fecal egg shedding rate were conducted for the first year. This research contributes to National Program 101 Food Animal Production, Component 2 Enhancing Animal Adaptation, Well-Being and Efficiency in Diverse Production Systems, Problem Statements 2A Enhance Animal Well-Being and Reduce Stress in Livestock and Poultry Production Systems, 2B Reducing Reproductive Losses and 2C Improving Efficiency of Nutrient Utilization and Conversion to Animal Products. 4.Accomplishments 1. Profiling the bovine immune response to stressors Weaning stress and transport stress are examples of production stressors that can be detrimental to animal well-being, resulting in substandard performance and increased costs associated with recovery. A research model that consists of administration of bacterial lipopolysaccharide (LPS) is often used to study stress induced inflammatory response. Typically, cortisol and tumor necrosis factor-alpha (TNF-alpha), a cytokine involved in the immune response, are used to evaluate stress. A study by USDA – ARS - STARS evaluated concentrations of five different cytokines, including TNF-alpha, and four acute phase proteins also involved in the immune response. Administration of LPS increased serum concentrations of cortisol, TNF-alpha, interleukin 1-beta, interleukin-6, interferon-gamma, and serum amyloid A. Rectal temperature and respiration rate were also increased following LPS administration. Serum concentrations of some cytokines and acute phase proteins were not altered by LPS challenge. These results to our knowledge are the most complete characterization of the bovine acute-phase response to an endotoxin (LPS) challenge. Additional research to determine the immune response to other stressors across cattle breeds is being conducted. This research contributes to National Program 101, Component 2 Enhancing Animal Adaptation, Well-Being and Efficiency in Diverse Production Systems, Problem Statements 2A Enhance Animal Well-Being and Reduce Stress in Livestock and Poultry Production Systems, 2B Reducing Reproductive Losses and 2C Improving Efficiency of Nutrient Utilization and Conversion to Animal Products. 5.Significant Activities that Support Special Target Populations None. 6.Technology Transfer Number of New Commercial Licenses Executed 1 Review Publications Heaton, M.P., Keele, J.W., Harhay, G.P., Richt, J., Koohmaraie, M., Wheeler, T.L., Shackelford, S.D., Casas, E., King, D.A., Sonstegard, T.S., Van Tassell, C.P., Neibergs, H.L., Chase, C.C., Kalbfleisch, T.S., Smith, T.P., Clawson, M.L., Laegreid, W.W. 2008. Prevalence of the prion gene E211K variant in U.S. cattle. BioMed Central (BMC) Veterinary Research [journal online]. 4:25. Available: (http://www.biomedcentral.com/1746-6148/4/25).