Quality and quantity of chicory, lucerne and red clover production under irrigation

The quality and quantity of production from irrigated lucerne, chicory and red clover swards were compared over six years (30 November 1996 30 June 2002) on a Wakanui silt loam at Lincoln University. Mean annual yields from lucerne swards (21 t DM/ha) were 3.9 t/ha greater than chicory and red clover over five perennial regrowth seasons. Sown species gave 100% of dry matter (DM) production in the first regrowth season, but by the fifth season sown species gave 65, 55 and 0% of DM production for chicory, lucerne and red clover respectively. Utilised herbage had a similar metabolisable energy (ME) content for all three species (10.9 11.6 MJ/ kg/DM). The crude protein (CP) content of utilised herbage was also similar for lucerne and red clover (0.25-0.29 g/g DM), but chicory had a lower CP content (0.18 g/g DM). This combined with utilisation data to show lucerne swards provided 30% greater annual CP and ME intake for grazing stock than either chicory or red clover. This demonstrated the greater potential of lucerne to improve livestock production from high value land. Changes in lucerne herbage quality were also analysed within regrowth cycles to examine the influence of the time of grazing on CP and ME intake. The fraction of palatable lucerne herbage decreased linearly from 100% at 700 kg/ha standing DM to 57% at 4300 kg/ha standing DM. The CP and ME contents of the palatable fraction of lucerne herbage were always higher than the post grazing residual. This highlights the selective grazing of the stock, which consumed 80% of total CP and 70% of total ME for a crop of 4300 kg/ha standing DM. This grazing preference shows that delaying defoliation will not reduce potential stock production, unless stock are forced to consume the low quality stem in standing herbage.Hamish Brown acknowledges the New Zealand Foundation for Science, Research and Technology for financial support during this study