Tall fescue pastures are an important part of the agricultural landscape in the southeastern USA. The development of tall fescue seed sources with low-ergot-alkaloid-producing strains of Neotyphodium endophyte has raised a number of questions regarding pasture ecology, animal performance, and nutrient cycling. We evaluated various plant and animal responses during the first three 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 endophyte tended to outcompete endophyte-free pastures from initial weed pressure of annual ryegrass. Cattle gain and stocking capacity were not affected by nutrient source averaged across a year. 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 weight gain was depressed with wild endophyte only in spring and autumn, and only marginally significantly depressed averaged across the 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.