Effects of year-round stocking rates and stocking methods on performance of cow-calf pairs grazing dallisgrass-common bermudagrass pastures overseeded with annual ryegrass

Abstract

Beef producers throughout the United States frequently are restricted to a fixed land area that varies considerably in carrying capacity throughout the year. Much of the research that has focused on stocking rate and methods (continuous, rotational) has failed to recognize the inability of most producers to use a variable stocking rate. Two sets of 4 adjacent pastures, each containing a mixed warm-season, perennial grass sod [common bermudagrass, Cynodon dactylon (L.) Pers.; dallisgrass, Paspalum dilatatum Poir.] were overseeded to ‘Marshall’ annual ryegrass (Lolium multiflorum) in the autumn of 3 consecutive years. Within each set of 4 pastures, one of the following grazing treatments was randomly assigned each pasture: continuous stocked at a low, medium, or high stocking rate (CL, CM, and CH) and rotational stocked (8 paddocks) at a high stocking rate (RH). Low, medium, and high stocking rates were 1.25, 2, and 2.75 cows/ha, respectively. Brangus cows and their suckling calves were stocked on treatment pastures in February 1999. Available forage mass tended to be greater (P = 0.10) for CL than CM in the late spring and was greater (P < 0.05) for CL than CM in the summer grazing season. Differences in forage nutritive value were largely associated with the stocking method comparison, favoring CH in the early spring (percent CP, percent in vitro true digestibility, and percent ADF; P < 0.01) and summer (percent CP and percent ADF; P < 0.01) grazing seasons. Cow-calf productivity, as measured by kilograms of calf wean weight per hectare, increased (P < 0.01) in response to increases in stocking rate, but was similar between the continuous and rotational stocking methods at the high stocking rate.