- Animals: bovine, sheep
- Animal Production: grazing - continuous, mineral supplements, pasture renovation, housing, stockpiled forages, watering systems, winter forage
- Education and Training: display, extension
- Farm Business Management: budgets/cost and returns, agricultural finance
Tall fescue (Festuca arundinacea) is a cool-season grass grown on over 20 million ha of pastureland and hayfields in the southeastern USA (Bouton, 2000). Despite agronomic attributes that make it an attractive forage crop, tall fescue is associated with fescue toxicosis, a condition that alters ruminant grazing behavior (Seman et al., 1999) and adversely affects cattle performance (Stuedemann and Hoveland, 1988). Animal toxicity problems result from grazing wild-type toxic endophyte-infected (E+) tall fescue. Endophytes (Neotyphodium coenophialum) within tall fescue plants impart positive agronomic qualities, e.g., enhanced drought tolerance and improved vigor. Plant breeders developed endophyte-free (E-) cultivars, which are non-toxic to livestock. However, plant persistence is lower in E- than in E+ tall fescue (Hill et al., 1991), and a higher level of management is required to maintain productive E- forage stands.
Non-ergot alkaloid-producing endophyte-infected (AR502 and AR542) tall fescue was developed by re-infecting E- tall fescue cultivars with non-ergot alkaloid-producing endophyte strains. Better stand survival than E- checks and survival similar to E+ checks has been observed in AR502 and AR542 tall fescue when subjected to close grazing in bermudagrass (Cynodon dactylon) sod (Bouton et al., 2002). In addition, AR502 and AR542 N. coenophialum strains have been shown to produce none of the ergot alkaloids responsible for toxicosis in grazing ruminants. Grazing research trials conducted in lambs (Fletcher et al., 2000; Bouton et al., 2002) and steers (Nihsen et al., 2000) have shown that non-ergot alkaloid-producing endophyte-infected tall fescue pastures provide animal performance similar to E- tall fescue and superior to E+ tall fescue without indications of toxicosis.
The objectives of the present study were to evaluate animal performance, toxicosis, and grazing behavior in stocker cattle grazing AR502, AR542, E-, and E+ Jesup, Georgia-5, and Kentucky-31 tall fescue pastures.