A comparison of temperate pasture species mixtures selected to increase dairy cow production and reduce urinary nitrogen excretion

Two short‐term dairy cow grazing experiments in mid‐lactation (late spring) and late‐lactation (late summer), were conducted in the Waikato region of New Zealand, to determine the effect of pasture species mixtures on urinary nitrogen (N) concentration and milk solids production. The mixtures included perennial ryegrass, tall fescue, lucerne and narrow‐leaved plantain (cv. Tonic), structured to compare the two grass species, both with and without plantain. With plantain, apparent intake of plantain was 46%–70% of dry matter intake and estimated water intake was increased by 8%–21% over grass‐lucerne swards. This led to significantly lower N concentrations of spot‐sampled urine, by 38% in summer and 21% in spring, but no difference in milk production. A decline in apparent N intake was also implicated in summer. The effect of relatively high levels of plantain intake on reducing urinary N concentration is likely to be positive for reducing N leaching risk, particularly in late‐lactation.