Effect of Interseeding Legumes into Endophyte‐Infected Tall Fescue Pastures on Forage Production and Steer Performance

Grazing and subsequent finishing performances of steers ( Bos taurus ) (n = 135) that grazed high‐endophyte [ Neotyphodium coenophialum Glen, Bacon, Price, and Hanlin (formerly Acremonium coenophialum )] tall fescue ( Festuca arundinacea Shreb.) pastures interseeded with lespedeza ( Lespedeza stipulated Maxim.), ladino clover ( Trifolium repens L.), or red clover ( Trifolium pratense L.) were evaluated during 1995, 1996, and 1997. Nine 5‐acre established pastures of ‘Kentucky 31’ tall fescue with approximately 70% endophyte infection were used in a randomized complete block design containing three replications of each legume treatment. Pastures were seeded with legumes each year in late winter, and steers grazed continuously from early spring to mid‐fall. At the end of the grazing phase, steers were finished for slaughter. Legume cover, available forage dry matter, grazing and subsequent feedlot performances of steers, and carcass parameters were measured. Total available forage dry matter was similar among legume treatments. A significant ( P < 0.01) year × treatment interaction affected grazing‐ phase gain. Grazing performance was similar ( P > 0.05) among legume treatments in 1995 and 1996. In 1997, steers grazing ladino clover pastures gained 36% more ( P < 0.01) and 28% more ( P < 0.01) than those grazing lespedeza and red clover pastures, respectively. Gains by steers grazing red clover and lespedeza pastures were similar. Legume treatment during the grazing phase had no effects on subsequent finishing performance. Total gains (grazing + finishing) were similar among legume treatments in 1995 and 1996; however, in 1997, steers that grazed ladino clover had higher ( P 0.01) overall gains than those that grazed red clover or lespedeza. Research Question Tall fescue, the primary cool‐season perennial grass in the USA, has a reputation for poor performance by grazing livestock because of the presence of a fungal endophyte. Cattlemen using high‐endophyte tall fescue pastures either can tolerate depressed gains from their cattle or seek to improve grazing performance by destroying existing stands of fescue and replacing them with endophyte‐free fescue or other forages or by interseeding legumes into existing pastures to reduce the adverse effects on animal performance. Replacement with endophyte‐free fescue is sometimes not a viable option since much of the land where high‐endophyte fescue is being grown is not suitable for tillage and problems with stand persistence when endophyte‐free fescue is subjected to grazing and drought stress. Therefore, producers must select management options that will minimize the effects of the endophyte. Interseeding with legumes is perhaps one of the most viable options. This study was conducted to compare grazing and subsequent finishing performances of stocker steers grazing three legumes interseeded into existing high‐endophyte tall fescue pastures. Literature Summary Ladino clover is the legume most commonly seeded with tall fescue; however, alfalfa, red clover, and lespedeza also are used in specific areas of the USA. Previous research has indicated that addition of legumes to tall fescue pastures will result in small but consistent increases in digestibility that are sufficiently large to have potential economic consequences on animal production. Although interseeding legumes offers potential to improve nutritive quality, increase gains of grazing livestock, and reduce N fertilizer rates, N fertilization in monoculture results in more consistent production of cool‐season forage. Previous research to evaluate interseeding legumes in tall fescue has been conducted primarily in agronomic plots that were harvested mechanically rather than by grazing livestock. The presence of legumes in high‐endophyte fescue generally has resulted in higher grazing and total gains than N fertilization with little effect on finishing performance or carcass characteristics. Research comparing grazing and subsequent feedlot performances of stocker cattle grazing fescue pastures interseeded with various legumes is very limited. Study Description A randomized complete block design containing three replications was used to compare legume establishment, forage production and grazing, and subsequent finishing performances of stocker steers grazing high‐endophyte tall fescue pastures interseeded with ladino clover, lespedeza, or red clover during 1995, 1996, and 1997. Applied Question Which legume (ladino clover, lespedeza, or red clover) interseeded in highendophyte fescue pasture will produce the highest grazing gains by stocker cattle? Although total available dry matter production was similar among legume treatments, interseeding high‐endophyte fescue pastures with ladino clover produced higher stocker gains during the grazing phase than interseeding with lespedeza or red clover. Gains of steers grazing pastures interseeded with lespedeza or red clover were similar. What impact does legume treatment during the grazing phase have on subsequent finishing performance of stocker cattle backgrounded on highendophyte tall fescue pasture? Legume treatment during the grazing phase had no effects on subsequent finishing gains. Subsequent finishing gains were similar for stocker steers that had previously grazed high‐endophyte tall fescue pasture interseeded with ladino clover, lespedeza, or red clover.