The response of spring calving cows and their calves to sward height

Abstract

There is a need to introduce objectivity into the management of grassland under continuous stocking so that management decisions can be taken in response to changing conditions, and at the same time allow the consequence of these decision to be predictable. There is much interest in using sward height as an objective criterion by which to manage grassland under continuous stocking. An experiment was conducted to examine the performance of spring calving cows and their calves when continuously grazing swards maintained at a range of sward heights.Initially nine cows (four Hereford x Friesian and five Blue-Grey) and their Charolais cross calves which had been born in March - April were turned out in mid-May to each of five sward surface height treatments. Treatments 1, 3 and 5 were one field and Treatments 2 and 4 in another. The botanical composition of each treatment is shown in Table 1. Sward length was measured twice weekly using the H.F.R.O. Swardstick, and maintained by the addition and removal of non-experimental cows and calves. Because of excessive rainfall and very wet soil conditions the numbers of annuals were reduced below nine on some of the treatments, and the two lowest sward height treatments were abandoned in mid-August because of damage to soil structure. From mid-August until the end of September only the upper three treatments continued.