Tall fescue pastures are an important part of the agricultural landscape in the southeastern USA. Tall fescue seed sources with low-ergot-alkaloid-producing strains of Neotyphodium endophyte have raised a number of questions regarding pasture ecology, animal performance, and nutrient cycling. We evaluated various plant and animal responses during the first five years of an experiment on a Typic Kanhapludult. Treatments were a factorial arrangement of nutrient source (inorganic and broiler litter) and Jesup tall fescue-endophyte association (endophyte-free, novel endophyte with low ergot alkaloid production, and wild endophyte with high ergot alkaloid production). Pastures were grazed with yearling Angus heifers whenever sufficient forage was available. Basal ground cover was dominated by tall fescue (>70%), but pastures with wild endophyte tended to outcompete novel and endophyte-free pastures from initial weed pressure of annual ryegrass. Cattle performance was lower in pastures with wild endophyte compared with novel or endophyte-free pastures in winter, spring, and autumn, but not in summer; a result contrary to expected heat-related symptoms of fescue toxicosis in the region. Since pastures with wild endophyte could support more cattle, because of reduced intake per head, total cattle gain was depressed with wild endophyte only in spring and autumn, and not significantly throughout the entire year. Results suggest significant seasonal pasture responses to nutrient source and tall fescue-endophyte association that can be used by producers to maximize production opportunities and minimize negative environmental pressures.