2004 Annual Report 4.What were the most significant accomplishments this past year? This report serves to document research conducted under a specific cooperative agreement between ARS and the Montana State Univesity, Bozeman. Additional details of research can be found in the report for the parent CRIS 5434-31000-014-00D - Develop Beef Cattle Better Suited for Sustainable Production. In a 2x2 factorial experiment to evaluate effects of transportation stress and treatment with flunixin meglumine, we found flunixin meglumine reduces early embryonic mortality in beef females. Treatments were applied to heifers and cows approximately 14-d following artificial insemination. Pregnancy rates of transported and control females were similar. However, pregnancy rates of females treated with flunixin meglumine were 10% greater (P=0.03) than non-treated females. Future trials, containing a control group without handling until pregnancy diagnosis may need to be conducted to determine if animal handling for data collection impacts embryonic mortality. Traits indicative of male fertility have been identified and are commonly measured in evaluating bulls before the breeding season. Estimates of heritability for birth weight, scrotal circumference, ejaculate volume, and sperm concentration, motility, and percents normal, live, and primary and secondary abnormalities were 0.46, 0.57, 0.09, 0.16, 0.22, 0.34, 0.23, 0.09, and 0.13, respectively. Estimates of genetic correlations between birth weight and scrotal circumference, ejaculate volume, and sperm concentration, motility, and percents normal, live, and primary and secondary abnormalities were 0.36, 0.07, 0.58, 0.21, 0.20, 0.34, -0.25, and 0.05, respectively. The moderate heritability estimates for scrotal circumference and several of the semen traits evaluated, imply improvement in these traits can be achieved through genetic selection. The genetic correlations between birth weight and semen characteristics indicate that there may be some negative impacts on bull fertility if selection for low birth weight is practiced.