The objective of this study was to investigate urinary nitrogen (N) excretion, grazing and urination behaviour of dairy heifers grazing pasture, chicory and plantain. A 35-day trial was conducted with 56 Friesian x Jersey heifers aged 9-10 months. Heifers were blocked into five treatments balanced for their live weight and breeding worth: 100% ryegrass/white-clover pasture (PA; n = 12); 100% chicory (CH; n = 10); 100% plantain (PL; n = 12); 50% pasture + 50% chicory (PA+CH; n = 10); and 50% pasture + 50% plantain (PA+PL; n = 12). Feed was offered every three days with allowance calculated according to feed requirement for maintenance plus live weight gain of 0.8 kg/day. Measured urinary-N concentration, estimated daily urinary-N excretion (UN) and urinary output were similar among treatments. During the first six hours after feed allocation, heifers spent more time idling and less time ruminating on CH and PL than on PA. The CH and PA+CH groups urinated more frequently than other groups. Data from this study indicate that heifers grazed chicory urinated more frequently without increasing daily UN and may potentially reduce N loading from soil. Future study is needed to take account of urinary N excretion diurnal variation.
Proceedings of the New Zealand Society of Animal Production, Volume 75, Dunedin, 70-73, 2015
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