Effect of Continuous or Rotational Grazing on Growing Steer Performance and Land Production

A grazing trial utilizing smooth bromegrass pastures was conducted from April to September (156 d) in 2 consecutive years to evaluate the effects of differing grazing strategies on growing steer performance and animal production per unit of land. In each year, 71 steers (initial BW = 313 kg; SD = 6) were assigned to 1 of 3 treatments with 3 replications per treatment. Treatments included 2 continuous grazing treatments (low (LO) or high (HI) grazing intensity) and a rotational grazing treatment (ROT). One HI replication was an outlier due to poor grass growth (62% of other HI replications) and was therefore removed from each year of the dataset. Cattle on the HI and ROT treatments were initially stocked at 9.88 AUM (308 kg of forage)/ha while LO cattle were stocked at 6.82 AUM/ha. All pastures were fertilized with 89.75 kg N/ha prior to the grazing season. Sward heights and density were collected at the beginning and end of each grazing season to estimate available forage and determine changes in amount of available forage. Put and take steers were utilized to maintain similar grazing pressure among treatments. The grazing season was divided into 5 cycles and steers in the rotationally grazed treatment were rotated every 4 days during the 1^st and 5^th cycle and every 6 days during the 2^nd, 3^rd, and 4^th cycle. Ending BW (404, 401, and 404 kg for LO, HI, and ROT, respectively) and ADG (0.59, 0.56, and 0.58 kg/d for LO, HI, and ROT, respectively) did not differ among treatments (P ≥ 0.85). However, calculated actual AUM/ha, was greater for HI (11.9 AUM/ha) and ROT (12.1 AUM/ha) treatments compared to the LO (10.8 AUM/ha) treatment (P ≤ 0.01). At the beginning of the grazing season, LO pastures had greater available forage than HI pastures (2028 vs 1682 kg/ha; P = 0.07), while ROT pastures were intermediate (1755 kg/ha) and did not differ from either LO or HI pastures. However, at the end of the grazing season, available forage did not differ among treatments (P = 0.35) suggesting appropriate grazing pressure was applied. These data suggest that, when intensively managed to maintain a constant grazing pressure, continuous grazing at a high stocking rate can yield similar individual animal performance and animal production per unit of land as similarly stocked rotational grazing, at least in the short term.