Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1998
Publication Date: N/A
Citation: Interpretive Summary: Tall fescue is a cool-season perennial grass that is widely adapted and persists under poor management. Tall fescue has not had widespread popularity because cattle grazing it can exhibit tall fescue toxicosis. Cattle with tall fescue toxicosis have elevated body temperatures, rough hair coats, and poor growth. Tall fescue toxicosis has its most severe impact during the summer when humidity and air temperature are high. The economic loss attributed to tall fescue toxicosis costs are estimated to be $600,000,000. Tall fescue toxicosis disproportionately affects small farmers because geographical distribution of tall fescue coincides with that of smaller scale farms. Research is needed to determine cost effective ways of feeding cattle during the summer in order to reduce losses associated with the toxicosis. This research found that feeder cattle that had been on tall fescue pasture in the spring had acceptable growth during hot summer months if they grazed tall fescue supplemented with a poultry litter-corn mixture or were transferred to eastern gamma grass pastures. These results are of interest to other scientists, extension agents, and ranchers because they provide two cost effective means of boosting cattle gains during the summer.
Technical Abstract: It is generally not recommended to graze endophyte-infested tall fescue (Festuca arundinacea Schreb.) in the late spring and summer when the effects of fescue toxicosis on cattle weight gains can be extreme. Stocking rate (3, 4, 5, and 6 steers/ha) effects were evaluated in 1997 and 1998 for two methods of avoiding poor cattle performance during the late spring and summer (compensation period) for steers that were conditioned to grazing tall fescue in the early spring. During the compensation phase, one replicate of each stocking rate was randomly assigned to 1-ha pastures of eastern gamagrass (Tripsacum dactyloides L.), and the other replicate of each stocking rate remained on tall fescue and the steers were fed a 1:1 mixture of broiler litter and corn at 2.27 kg as fed/steer/d. Average daily gain for eastern gamagrass during the compensation phase declined linearly as stocking rate increased, but ADG for tall fescue plus broiler litter-corn tended to increase as stocking rate increased. As a result, ADG and liveweight gain (kg/ha) with heavier stocking were higher for tall fescue plus broiler litter-corn, whereas with lighter stocking the responses were higher for eastern gamagrass. At the conclusion of the compensation phase in 1998, steers on tall fescue plus broiler litter-corn pastures had lower serum prolactin levels and there was a higher proportion of steers with rough haircoats on tall fescue than on eastern gamagrass. Results of the study show that either eastern gamagrass or supplementation with broiler litter on tall fescue pastures can provide acceptable performance of stocker cattle with responses affected by grazing pressure; however, symptoms of fescue toxicosis can still occur.