Herbage biomass and intake of beef cows with calves grazing a grass-legume pasture in southern Ontario

Intake and performance of 40 spring-calving cows with calves was investigated under a rotational grazing management system across three consecutive summers. A 19.2 ha pasture was divided into sixteen 1.2 ha fields with each field being further subdivided into eight 0.15 ha paddocks. Five cows with calves belonging to one of two breed groups (large vs. medium framed) and two body conditions (high vs. low) were randomly assigned to graze each of eight field pairs from May to October of each year. Paddocks not grazed by cow-calf pairs were grazed by yearling heifers or mechanically harvested as hay or silage. Grazing was managed by setting target sward heights for exit of each paddock at 8 to 10 cm and allowing a minimum of 25 to 30 d for regrowth. Paddocks were topclipped and fertilized with 34 kg ha−1 of nitrogen (N) immediately following the second grazing of each paddock. Sward surface height data were collected from 40 measurements taken immediately pre- and post-grazing in each paddock as well as durin...