Productivity and nutritive value of 'Florakirk' bermudagrass as affected by grazing management

'Florakirk' bermudagrass [Cynodon dactylon (L.) Pers.] is a recently releas ed cultivar for the lower southeastern USA, but its evaluation under grazin g has been limited to southern Florida. Herbage accumulation, crude protein (CP), and in vitro digestible organic matter (IVDOM) responses of Florakir k to grazing management were studied in 1993 and 1994 on a sandy siliceous, hyperthermic Ultic Haplaquod in northern Florida, Treatments were replicat ed 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 s tubble 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 maxim ized when pastures were grazed to a 24-cm SH every 7 d in 1993. and to 24 c m every 35 d in 1994, Lowest herbage accumulation occurred when pastures we re grazed to an 8-cm SH every 21 d, Treatment combinations involving GC 7 w ere associated with high herbage accumulation in both pears of the study. N utritive value varied relatively little across the range of treatments impo sed. 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 pears, In vitro digestible organic matter concentration was greates t at short SHs for all but the shortest GCs in 1993 and was greatest at int ermediate GCs in 1993, Florakirk herbage accumulation was affected primaril y by SH, and nutritive value was effected primarily by GC. Grazing to a SH of approximately 20 cm every 14 d is predicted by regression models to resu lt in near maximum levels of both herbage accumulation and nutritive value.