Early literature reporting research on the nutritive value and use of tall fescue by animals before the recognition of the existence of the fungal endophyte and the removal of the toxic products often contains animal responses that are difficult or impossible to interpret or reproduce. This permits the opportunity to select data that will support nearly any point of view regarding animal performance on tall fescue. Consequently, animal response data obtained during that earlier period are of historical interest but of limited use in estimating the value of tall fescue in production systems. From a historical perspective, the literature is valuable in detailing the discovery and significance of the toxic endophyte. Second, based on our present knowledge, studies in the literature that were not confounded can verify certain plant-animal responses and basic endophyte alkaloid and plant associations.
With the recent identification and successful insertion of known endophytes into current or new tall fescue cultivars, experiments now can be conducted to evaluate the nutritive value and quality of tall fescue forage without the confounding influence of toxins from the fungal endophyte. In such experiments the contribution of the nontoxic endophyte on the physiology of the plant, as related to growth and persistence, also can be assessed. Studies such as small plot yield and persistence trials, grazing evaluations, and animal stall trials need to be conducted with the improved tall fescue cultivars and with comparisons among other cool-season grasses. Combining yield, persistence, nutritive value, and quality estimates in these studies is urgently needed as opposed to focusing simply on any one entity. In addition, care needs to be exercised in these studies to include the type of treatments needed based on our previous 50 yr of experience.