Submitted to: Arkansas Experiment Station Research Series
Publication Type: Experiment Station
Publication Acceptance Date: 8/31/2006
Publication Date: 12/2/2006
Citation: Ogden, R.K., Coffey, K.P., Coblentz, W.K., Caldwell, J.D., Hess, T., Hubbell, D.S., Akins, M.S. 2006. Cow and Calf Performance While Grazing Tall Fescue Pastures with Either the Wild-Type Toxic Endophyte or a Non-Toxic Novel Endophyte. Research Series 545. Arkansas Animal Science Department Report. 9:138-139. Interpretive Summary: Tall fescue is an important component of pastures throughout the Upper South. Most tall fescue throughout this region is infected with a fungal endophyte that produces ergot alkaloids that are toxic to grazing ruminants (wild-type), and limit their performance. From a plant perspective, the relationship between the host plant and the endophyte is beneficial, and it improves plant persistence relative to endophyte-free plants. Recently, endophyte/host plant associations have been developed that produce low or nil concentrations of ergot alkaloids (novel-type), but also may retain advantages for plant persistence enjoyed by wild-type endophyte/host plant associations. These novel-type associations need to be evaluated intensely under production management schemes. In the first year of a 2-year study, cows grazing fescue pastures with a novel endophyte had higher pregnancy rates and their calves had heavier weaning weights than cows grazing the wild-type fescue pastures. Therefore, novel endophyte technology could prove to be beneficial for producers in northern Arkansas. However, further evaluations are needed to determine if plant vigor and persistence, as well as the overall economic benefits of using novel endophyte-tall fescue associations are superior to wild-type fescue pastures.
Technical Abstract: Fescue (Festuca arundinacea, Schreb.) pastures are common in Northwest Arkansas but cattle performance has declined due to the toxicity caused by the wild-type endophyte Neotyphodium coenophialum in the fescue plant. Gelbvieh x Angus crossbred cows (n = 52; 1,023 lb initial BW) were allocated randomly by weight and age to one of four 25-acre pastures of tall fescue containing either the wild-type toxic endophyte (E+) or a non-toxic novel endophyte (HM4; 2 replicates each). Cows confirmed as pregnant began grazing the experimental pastures on October 15, 2004. Extremely dry summer conditions resulted in depleted forage reserves. Cows were then moved to a bermudagrass pasture and fed bermudagrass hay. Pastures with HM4 were removed before those with E+ and were offered 1,808 lb more hay (P = 0.20) than those on E+. Cow weight and BCS changes during the year were not different (P > 0.20) between HM4 and E+, but a greater percentage (P < 0.01) of cows grazing HM4 were pregnant at the time of weaning. Calf birth date and birth weight were not different (P > 0.37) between forages, but actual and adjusted weaning weights, and calf gain from birth to weaning tended to be greater (P < 0.06) by 41, 44, and 38 lb, respectively, from HM4 compared with E+ pastures. Therefore, Arkansas producers could improve performance of their cows and calves by using new novel endophyte technology, but should weigh the cost against the benefits before renovating large acreages of existing E+ pastures.