Effect of grazing stage and intensity on the utilization efficiency and botanical composition in orchardgrass dominant pasture
Seo, S.; Kim, J.K.; Shin, J.S.
RDA Journal of Agricultural Science Livestock 38(1): 802-810
This experiment was conducted to determine the effects of grazing stage and intensity on the residual height after grazing, forage utilization efficiency, and botanical composition in orchardgrass dominant pasture, 1989 and 1990. The grazing stages were 20 apprx 25cm, 30 apprx 35cm, and 40 apprx 45cm of plant height, and high and medium grazing intensity were set by the number of growing cows (initial body weight: 230 apprx 250kg), which was adjusted according to the pasture production. The high level of grazing intensity was 150% of medium intensity. Annual grazing frequency was 10 times in 20 apprx 25cm, 8 times in 30 apprx 35cm, and 6 times in 40 apprx 45cm of plant height. Residual height after grazing was increased with increasing of plant height at grazing: 7.6cm in 20 apprx 25cm, 8.5cm in 30 apprx 35cm, and 9.0cm in 40 apprx 45cm of height. Also residual height was higher in medium grazing intensity (9.4 apprx 11.0cm) than that of high intensity (5.8-6.0cm). The efficiency of pasture utilization was 75.3% and 75.4% in 20 apprx 25cm and 30 apprx 35cm, respectively. However, pasture utilization was low as 69.2% in 40 apprx 45cm. Also the efficiency was higher in high grazing intensity (76.3-81.9%) than that of medium intensity (62.1 apprx 69.1%). Good coverage of pasture plants was observed in 20 apprx 25cm and 30 apprx 35cm, and medium grazing intensity. Higher weeds and bareground were found in 40 apprx 45cm of plant height, particularly in high grazing intensity. In spring, orchardgrass was dominant species in all plots, but the plant was changed into tall fescue and Kentucky bluegrass in summer, and tall fescue in autumn. The main weed developed in this experiment was Digitaria sanguinalis. Based on the above results, it may be concluded that optimum grazing stage was 20 apprx 25cm and 30 apprx 35cm of plant height in pasture mixtures dominated by orchardgrass, and medium grazing intensity was very desirable for pasture persistence.