Abstract/Summary

Red clover (trifolium pratense), white clover (trifolium repens) and lucerne (medicago sativa) are currently the most viable forage legumes for european farming systems. Knowing the agronomy and feeding strategies representing ‘best practice’ for these forages in livestock production systems is key as the industry turns to low input forages to meet sustainability targets. The research question addressed in this thesis was whether these forage legumes could be grown and fed more efficiently, with a focus on their use in the UK dairy sector. Limitations to their utilisation are discussed and potential practical solutions were assessed. This included investigations into the effects of sowing timing and plant maturity on yield and feeding value of lucerne, and the effect of chop length and inclusion rate of lucerne silage in a total mixed ration with maize silage on dry matter intake, milk yield, total tract digestibility, and rumen functionality in both ‘normal’ and ‘challenging’ rumen environments of dairy cattle. Furthermore, to ensure precise diet rationing, the method by which most legume-containing silage samples are analysed for nutritional content in the UK (Near Infra-Red Reflectance Spectroscopy) was tested for accuracy for both grass-clover and lucerne silages. Improved grass-clover prediction equations were calibrated from the data collated in the study, which will be adapted for commercial implementation in the future. Key findings from these studies which can be used to enhance best practice guidelines for farmers included: (i) it was advantageous to sow lucerne in spring rather than autumn for greater yield and reduced weed burden, (ii) including lucerne silage in a TMR diet with maize silage at 25% of forage DM and at a short chop length was beneficial to dry matter digestibility, and therefore metabolisable energy supply, relative to inclusion at 75% of forage DM and a long lucerne chop length, and (iii) a high inclusion rate of lucerne silage in the diet can mitigate against sub-acute rumen acidosis risk resulting from short-term feed deprivation followed by refeeding.