The effect of harvest date on the domd, crude protein, SMCO and SCN⁻ contents of the lamina, petiole and stem of fodder kale

Maris Kestrel kale sown on 4 June 1980 was harvested on 14 occasions between 5 August 1980 and 18 March 1981 and the plants were divided into leaf lamina, petiole and stem. Samples were freeze‐dried, milled and analysed for digestible organic matter (DOMD), crude protein (CP), S‐methyl cysteine sulphoxide (SMCO, the haemolytic factor) and thiocyanate ion (SCN − , a goitrogen) contents. DOMD contents were low at the first harvest due to low organic matter contents and at the last harvest due to low digestibilities. Between these harvests average lamina, petiole and stem contents were 769, 842 and 840 g kg −1 DM respectively. CP contents declined from 5 August to 17 September when average lamina, petiole and stem contents were 206, 96 and 121 g kg −1 DM respectively. From 5 August to 14 October average lamina, petiole and stem SMCO contents were 5.44, 6.64 and 10.56 g kg −1 DM, respectively, compared with 9.04, 7.39 and 9.40 g kg −1 DM, respectively, from 11 November to 24 February. SCN‐ contents fluctuated up to 15 December and then remained constant at a slightly lower level. Average lamina, petiole and stem contents were 0.29, 0.15 and 0.08 g kg −1 DM respectively. Whole plant contents were calculated taking account of the relative dry matter yields of lamina, petiole and stem.