A study of the nutritive value of white clover (Trifolium repens L.) in relation to different stages of phenological maturity in the primary growth phase in spring

This paper reports the effects of onset of phenological maturity on the nut ritive value of white clover (Trifolium repens L.). The study comprised (i) examination of an extensive data set on nutritive value and (ii) investiga tion of the constituents of nutritive value, in vivo feeding value, protein degradability and metabolizable protein content of while clover harvested at three stages of maturity (early-flowering, full-flowering, ripe seed sta ges) during the primary growth phase in spring in Australia. The data set o n nutritive value showed a consistent pattern of high nutritive value durin g cool season months, progressive decline through spring and uniformly lowe r nutritive value over summer. Results from laboratory determinations, in s acco degradability studies and a digestibility trial on white clover harves ted at early-flowering, full-flowering and ripe seed stages were consistent with results from the data set on nutritive value. Onset of maturity durin g the primary growth phase in spring was accompanied by large changes in nu tritive value: neutral-detergent fibre (NDF) increased from 184 to 301 g kg (-1) dry matter (DM), nitrogen (N) declined from 36 to 20 g kg(-1) DM, in v itro digestibility declined from 0.74 to 0.65 and metabolizable protein con tent declined from 144 to 67 g kg(-1) DM from early-flowering to ripe seed stage. These nutritive value changes were accompanied by a decline of in vi va digestibility at the rate of 0.0032 d(-1) and an 0.2 reduction in volunt ary intake.