Intensive Grazing Management of Smooth Bromegrass With or Without Alfalfa or Birdsfoot Trefoil: Heifer Performance and Sward Characteristics

Over 3 yr, 324 (n=108 per yr) Holstein heifers (226±26 kg; ±SD) ranging in age from 5 to 7 mo were assigned to a 3×2 factorial arrangement of treatments to determine the effects of forage and grazing management system on animal performance, forage availability, and forage quality. The forage treatments were: 1) alfalfa and smooth bromegrass (ALF-BR), 2) birdsfoot trefoil and smooth bromegrass (BFT-BR), or 3) smooth bromegrass plus nitrogen (BR). The grazing management systems were: 1) a four-paddock system in which cattle were rotated based on time (4-p) or 2) a 12-paddock system in which cattle were rotated based on forage availability (12-p). Stocking rate was held constant at 3.75 animals per hectare. The ALF-BR and BR pastures yielded more available forage than BFT-BR pastures (9.86 and 10.04 vs 9.14 metric tons/ha). The ALF-BR and BFT-BR pastures, when compared to BR pastures, supported greater animal average daily gain (0.93 and 0.97 vs 0.83 kg/d) and increased animal gain per hectare (497.8 and 516.4 vs 443.3 kg/d). Legume-grass pastures also had lower neutral detergent fiber content than BR pastures. There were no differences in either animal gain or gain per hectare due to grazing system. Three years after seeding, BFT-BR and ALF-BR had a similar percentage of legume present within their respective pastures. Birdsfoot trefoil appears to be an acceptable substitute for alfalfa in properly managed grass-legume mixed pastures.