Comparison of Heifer Weight Gains and Forage Quality for Continuous and Short-duration Grazing Systems

Abstract

A study of animal performance and forage quality under continuous and short-duration grazing (SDG) systems was conducted with post-weaning heifer calves on smooth bromegrass (Bromus inermis) pasture for 2 years. There were 8 paddocks for each SDG cell. The animals were on pasture from early May through the middle of August in both years. Heifers assigned to the SDG system were moved among the rotational paddocks approximately every 2.5 days. In 1982, the grazing treatments were stocked at equal levels (2.9 animals/ha). The stocking rate was increased to 3.8 animals/ha on the SDG treatment in 1983, while the continuous system remained at 2.9 animals/ha. Animals were weighed and forage samples were collected at the completion of each rotation cycle. Average daily gain (ADG) was similar (continuous 0.48 kg/d vs. SDG 0.47 kg/d, P>.05) in 1982 when both systems were stocked equally. Available forage tended to be greater under the SDG system (3,141 vs. 3,786 kg/ha), but this difference was not significant. Forage quality did not differ (P>.05) between the grazing systems but did decline significantly in both systems during the grazing season. Individual paddocks of the SDG system did not differ significantly in forage quality. In 1983, ADG was similar for both grazing systems (0.56 and 0.52 kg/d, P>.05) and available forage also was similar (2,551 vs. 2,159 kg/ha). Crude protein content of the forage tended to be greater for the SDG system (7.9 vs. 8.5%, P<.05) in 1983. In vitro digestibility and crude protein content were lower, and cellulose and lignin concentrations were higher in forage from paddocks grazed later in the rotation sequence in 1983. The SDG system increased available forage when stocking rates were equal for the grazing systems, and this forage was effectively utilized at a higher stocking rate for the SDG system to produce more grain per ha (165.6 vs. 205.6 kg/ha) without sacrificing individual performance.