Herbage intake by beef cows is highly correlated with sward height and therefore intake can be managed in a predictable manner by controlling sward height. For beef cows this requires adjustment of the grazing area and conservation of herbage which is not grazed, with the silage aftermath subsequently grazed later in the summer. Year-to-year variation in herbage growth rate will result in variation in the amounts of silage produced. Most grazing experiments do not consider this year-to-year variation, but it constitutes one of the major features which has to be accommodated in the operational management of beef cow systems which are based on pastoral resources.

During three consecutive summers, 40 spring-calving Hereford x Friesian beef cows and their Charolais-cross calves grazed perennial ryegrass-dominated swards receiving 200 kg N/ha at one of two annual stocking rates (2.0 or 2.5 cows/ha) at one of two sward heights (4 to 5 (short) or 7 to 8 cm (tall)) in a 2x2 factorial experiment, replicated twice.