Published online by Cambridge University Press: 02 September 2010
An experiment was conducted to examine the effects of dietary fibre and starch levels on the response to condition score at calving. Fifty-two cows were used over two winter feeding periods, with 24 and 28 different cows in each. Twelve weeks before their expected calving date, cows were paired and the level of feeding adjusted to attain mean condition scores at calving of 2·0 (T) and 3·5 (F) within pairs. At calving, pairs of cows were allocated to treatment HF or LF, giving four groups in total. Each day for the first 16 weeks of lactation, all cows were offered 10 kg dairy concentrate containing either high-fibre/low-starch (FHF and THF), or low-fibre/high-starch (FLF and TLF), 2 kg sugar-beet pulp and hay ad libitum. Two cows from each group were used to determine apparent digestibility of the whole diet each year, using chromium III oxide as a faecal marker. Eight steers were used to determine the degradabilities of dry matter, nitrogen and fibre in the two concentrates and to provide rumen fluid samples for volatile fatty acid determination.