Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/27/2006
Publication Date: 5/1/2007
Citation: Stuedemann, J.A., Franzluebbers, A.J. 2006. Cattle performance and production when grazing bermudagrass at two forage mass levels in the southern Piedmont. Journal of Animal Science. 85(5):1340-1350. Interpretive Summary: Bermudagrass is a typical pasture grass in the southeastern USA that can be grazed by beef cattle during the summer. Despite considerable research on cattle performance from bermudagrass, a gap exists in how low and high grazing pressure might affect cattle stocking rate, performance, and production over a number of years. Scientists at the USDA Agricultural Research Service in Watkinsville GA conducted a 5-year grazing study to investigate dynamics in cattle performance and production. During the first couple of years, cattle stocking rate and cattle gain were greater under high than under low grazing pressure. However by the end of five years, stocking rate and cattle gain had become similar, suggesting that high grazing pressure had reduced pasture productivity as a result of changes in plant community composition and surface soil condition. How grazing animals can alter pasture productivity and economic return needs to be a consideration in long-term management strategies on the 46 million acres of pastureland in the southeastern USA. This research will benefit (a) science by improving grazingland ecological theory, (b) producers by improving productivity, and (c) the environment by reducing land use stress.
Technical Abstract: Performance and production of stocker cattle on Coastal bermudagrass pastures are affected by forage allowance, but possible interactions with fertilizer nutrient source and time have not been well described. We evaluated three nutrient sources [inorganic, crimson clover cover crop plus inorganic, and broiler litter] factorially arranged with two grazing treatments on cattle stocking density, daily gain, and live-weight gain during five consecutive years. Across years, interactions between defoliation regime and nutrient source were rarely significant. Cattle performance tended to decline with time during the growing season under both defoliation regimes, perhaps as a result of declining forage quality, since performance was positively associated with growing season precipitation. Live-weight gain was greater with low than with high forage mass early in the growing season, but not necessarily later in the growing season, and was overall greater during early years, but became similar during later years of the study. Significant variation in cattle performance and production with time confirmed short-term seasonal effects, but suggested that long-term effects are important in maintaining productivity and environmental quality.