Replacing synthetic N with clovers or alfalfa in bermudagrass pastures. 3. Performance of growing steers

The objective of this study was to evaluate the performance of steers (n = 590, 263 +/- 30.6 kg) grazing alfalfa (ALF, Medicago sativa L.) or a combination of white (Trifolium repens L.) and red (Trifolium pretense L.) clovers (CLVR) inter-seeded into bermudagrass (Cynodon dactylon L. Pers.) pastures compared with fertilisation with 0 (0N), 56 (56N), or 112 (112N) kg nitrogen (N)/ha (n = 4, 0.8-ha pastures per treatment) in north-east Arkansas (USA) over 4 years. The carryover N benefit of CLVR or ALF was compared with N fertilisation rates during the fifth year on performance of growing steers (n = 120; 235 +/- 22.6 kg). Average daily gain increased with N application rate and legume pastures were similar to 56N; but liveweight gain per steer grazing legume pastures tended to be greater than 112N. Steer grazing days per hectare and liveweight gain per hectare were greater for ALF and CLVR than bermudagrass monocultures regardless of N fertilisation rate. Steer average daily gain, grazing days per hectare and liveweight gain per hectare for carryover N from legumes did not differ from 56N. These results indicate that replacing synthetic N by inter-seeding legumes into bermudagrass swards has the potential to improve individual animal performance and production per unit area and carryover benefits of legume N may be equivalent to 56 kg N/ha.