Abstract

In trials at Ona in 1986-87, grazing defoliation frequencies (GF) of 2, 4, 6 or 8 weeks using mob grazing by cattle were applied to established plots of 2 Paspalum notatum, 3 Hemarthria altissima and 3 Cynodon dactylon cultivars. DM productions, forage quality and crown total non-structural carbohydrate content from the initial cut of growth accumulated between Dec. and May varied significantly among grass entries but were independent of GF. H. altissima accumulated more DM during the cool period than the other 2 species. There was a significant interaction between GF and grass entries for DM yield, CP content and in vitro OM digestibility (IVOMD) during the June-Nov. grazing season. The 2-year av. DM yield from June to Nov. was unaffected by GF in P. notatum but increased linearly in H. altissima and curvilinearly in C. dactylon as GF decreased. Total annual DM yield was highest in H. altissima cv. Floralta averaging 16.8 t/ha and lowest in P. notatum cv. Tifton-78 and H. altissima PI 364869 averaging 8.7 and 8.3, resp. H. altissima had the highest IVOMD but the lowest CP content at all GF. IVOMD declined in C. dactylon when GF was decreased to >4 weeks. Total non-structural carbohydrate concn was highest in P. notatum and lowest in H. altissima and was not affected by GF. C. dactylon cv. Callie 35-3, H. altissima cv. Floralta and P. notatum were the most persistent.