PERFORMANCE OF ANGUS AND BRANGUS COW-CALF PAIRS GRAZING ALICIA BERMUDAGRASS AND COMMON BERMUDAGRASS-DALLISGRASS PASTURES

This research was designed to examine genotype x environment interacti ons in cow-calf growth performance of grazing animals. Angus and Brang us cow-calf pairs (minimum of six per breed) were allowed to rotationa lly graze (14-d intervals) treatment pastures from approximately May t hrough early October in each of 2 yr. Treatment pastures contained rel atively pure stands of Alicia bermudagrass (AP) or a mixed stand of co mmon bermudagrass and dallisgrass (CDP). Forage allowance was equalize d, using ''put-and-take'' cow-calf pairs, among forage and breed types at the initiation of each 14-d grazing interval. Forage samples were obtained in each paddock at the initiation of each grazing interval. F orage CP concentration was greater (P < .05; 13.5 vs 11.6%) and NDF co ncentration was less (P < .05; 63.8 vs 70.6%) for CDP than for AP. Dai ly weight loss was similar for Angus and Brangus cows, but it was grea ter (P < .05) for cows grazing AP than for cows grazing CDP. Calf ADG during the grazing season was 35% greater (P < .05) for CDP than for A P pastures and was 23% greater (P < .01) for Brangus than for Angus ca lves. Relative performance of Angus and Brangus cow-calf pairs was con sistent between forages; no breed x forage interactions were observed.