Productivity and Nutritive Value of ‘Florakirk’ Bermudagrass as Affected by Grazing Management

Abstract

‘Florakirk’ bermudagrass [Cynodon dactylon (L.) Pers.] is a recently released cultivar for the lower southeastern USA, but its evaluation under grazing has been limited to southern Florida. Herbage accumulation, crude protein (CP), and in vitro digestible organic matter (IVDOM) responses of Florakirk to grazing management were studied in 1993 and 1994 on a sandy, siliceous, hyperthermic Ultic Haplaquod in northern Florida. Treatments were replicated twice in a randomized block design and consisted of all combinations of three lengths of grazing cycle (GC) (7, 21, and 35 d) and three postgraze stubble heights (SH) (8, 16, and 24 cm). Actual grazing periods were from 1 to 12 h. Herbage accumulation ranged from 6.9 to 17 Mg ha−1 and was maximized when pastures were grazed to a 24‐cm SH every 7 d in 1993, and to 24 cm every 35 d in 1994. Lowest herbage accumulation occurred when pastures were grazed to an 8‐cm SH every 21 d. Treatment combinations involving GC 7 were associated with high herbage accumulation in both years of the study. Nutritive value varied relatively little across the range of treatments imposed. Crude protein concentration ranged from 96 to 113 g kg−1 in 1993 and from 121 to 134 g kg−1 in 1994. Lower CP was associated with longer GCs in both years. In vitro digestible organic matter concentration was greatest at short SHs for all but the shortest GCs in 1993 and was greatest at intermediate GCs in 1994. Florakirk herbage accumulation was affected primarily by SH, and nutritive value was affected primarily by GC. Grazing to a SH of approximately 20 cm every 14 d is predicted by regression models to result in near maximum levels of both herbage accumulation and nutritive value.