Effect of Seasonal Variation in the Fractionation Pattern of Lucerne Selected for Commercial Crop Processing in Australia

The study was conducted on an irrigated lucerne (Medicago sativa) crop (cv. Aurora) harvested at the late vegetative stage of maturity for processing and fractionation during autumn, spring, early and late summer. The experiment was carried out using replicated commercial-sized irrigation bays with lucerne dry matter (DM) yields estimated to average some 19 t OM/ha/year. Despite irrigation, the lucerne harvested during the late summer season had the lowest nitrogen content at the time of harvest and yielded less lower crude protein lucerne extract as compared to those crops harvested during the spring and autumn seasons. The lower efficiency of processing and fractionation observed during the summer season did not reduce the crude protein level in the processed crop below 15% dry weight which is considered as still being a full productive fodder for beef cattle. By adjusting the processing conditions it is possible to produce processed lucerne in pellet or cube form with a consistent crude protein level ranging from between 15% to 17% and thus adopting quality standards to lucerne products destined for the premium-priced but quality-demanding export market.