Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/27/2006
Publication Date: 9/1/2006
Citation: Coblentz, W.K., Coffey, K.P., Smith, T.F., Hubbell, D.S., Scarbrough, D.A., Humphry, J.B., Mcginley, B.C., Turner, J.E., Jennings, J.A., West, C.P. Popp, M.P., Hellweig, D.H., Kreider, D.L., and Rosenkrans, C.F., Jr. 2006. Using Orchardgrass and Endophyte-Free Fescue Versus Endophyte-Infected Fescue Overseeded on Bermudagrass for Cow Herds: Four-Year Summary of Cow-Calf Performance. Crop Science. 46:1929-1938. Interpretive Summary: Toxins produced by the fungus associated with tall fescue forages are known to limit livestock performance in the southeastern US, especially during summer months. Animal performance throughout this region could be improved by utilizing non-toxic, cool-season perennial forages, but (historically) these forages have not persisted adequately in the southern Ozarks. During a 4-year trial, cow-calf performance for cattle grazing intensively managed non-toxic pastures [orchardgrass (OG) or endophyte-free tall fescue (E-) mixed with bermudagrass] was compared with the performance of cattle grazing a mixture of toxic tall fescue (E+) and bermudagrass, which is found commonly throughout northern Arkansas. Over four years, actual and age adjusted 205-day weaning weights for calves raised on non-toxic pastures exceeded by 49 and 53 lbs, respectively, weights observed for calves raised on E+ pastures that were diluted by approximately 50% with bermudagrass and a variety of other forages. While it is apparent that this relatively high level of dilution within E+ pastures was not sufficient to completely negate the effects of toxins produced by the fungal endophyte associated with tall fescue, the mean actual weaning weight for calves raised on E+ pastures was 510 lbs, which is quite likely to be acceptable performance for small, part-time cow-calf producers in the southern Ozarks. Generally, cow performance differed only marginally for cows grazing E+ compared to E- or OG pastures. Overall, the magnitude of differences between cow and calf performance on OG or E- pastures compared to E+ was relatively small, and this may limit producer adaptation of OG and E- forages, especially when the additional management required for persistence in the southern Ozarks is considered.
Technical Abstract: A 4-yr trial was initiated in January 2000 to evaluate cow-calf performance on mixed-species pasture systems consisting of: i) endophyte-infected tall fescue (E+; Festuca arundinacea Schreb.) diluted by approximately 50% with common bermudagrass [Cynodon dactylon (L.) Pers.] and other forages; ii) endophyte-free tall fescue (E-) overseeded into dormant common bermudagrass; and iii) orchardgrass (OG; Dactylis glomerata L.) established under the same conditions as E-. The E- and OG pastures were grazed with either twice weekly (2W) or twice monthly (2M) rotation schedules, while pastures with E+ were grazed with 2M only. Actual weaning weights tended to be greater (P = 0.096), and age adjusted 205-d weaning weights and average daily gain from birth to weaning were greater (P 0.035) for calves raised on low-toxicity (E- or OG) pastures compared to those raised on E+. Over four years, calves raised on low-toxicity pastures exhibited 22- and 24-kg advantages in actual and 205-d adjusted weaning weights, respectively, compared to those raised on E+. Cows grazing OG and E- pastures exhibited greater (P 0.021) body weights and body condition scores (BCS) at calving than cows grazing E+ pastures. Furthermore, reductions in body weight and BCS between calving and weaning tended to be greater (P 0.088) for cows grazing E+ pastures. Calf performance was improved consistently by these low-toxicity pasture systems, but management requirements may limit adaptation by producers.