Effects of Prescribed Fire and Herbicide Application on Cattle Grazing and Herbage Production from Yellow Bluestem Pastures

Forage management practices influence the quantity and quality of forage available to grazing cattle. The objectives of this experiment were to determine the effects of prescribed fire or herbicides on the density of forbs, the production and nutritive value of the herbage, and the performance of beef steers grazing Yellow bluestem [Bothriochloa ischaemum (L.) Keng var. ischaemum (Hack.) Celarier and Harlan] pastures. The experiment was conducted in northwestern Oklahoma from 1998 through 2000, and the untreated pastures (control) were not burned or sprayed. The prescribed-fire treatment (PFT) occurred annually between March 27 and April 10. The herbicide treatment (HT) consisted of an annual application of 0.9 kg of 2,4-dichlorophenoxyacetic acid and 2.8 g of metsulfuron methyl per hectare. Compared with the control, forb densities were or tended to be decreased (P < 0.13) in PFT and HT pastures only in May and June of 1998; forb densities were not affected (P ≥ 0.45) in later months or years. Dry matter production of Yellow bluestem in August was not affected (P ≥ 0.10) by treatment, but CP concentration and in vitro OM disappearance were greater (P ≤ 0.05) in herbage collected early in the grazing season from PFT pastures than in that from control and HT pastures. Over the 92-d grazing period that started May 30 (initial stocking rate, 1.93 steers/ha), ADG and BW gain per hectare did not differ (P ≥ 0.74) among treatments. Forb control with prescribed fire or the herbicides used in this experiment did not improve the performance of beef cattle grazing Yellow bluestem pastures even though prescribed fire improved forage quality early in the grazing season.