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A short-term, dairy cow, grazing experiment was conducted in late-lactation (autumn) to determine the effect of fodder beet (FB) and maize silage supplementation on dry matter and nitrogen (N) intake, urinary N excretion and milk solids (MS; milk fat + milk protein) production. Seventy-two multiparous, lactating (224 ± 20.0 DIM; mean ± SD) Holstein-Friesian cows were randomly assigned (n = 24 per treatment; 8 per replicate) to one of three groups. Control animals were offered pasture (11 kg DM/cow/day) with maize silage (4 kg DM/cow/day; 'Maize'). The other two groups were either offered pasture (11 kg DM/cow/day) with 25% FB (4 kg DM/cow/day; 'FB25') or pasture (9 kg DM/cow/day) with 40% FB (6 kg DM/cow/day; 'FB40'). At the same supplement DM intake, diets containing maize silage or grazed FB had similar urinary nitrogen (UN) concentrations, but FB increased milk solids (MS) production. At 40% FB inclusion UN excretion was reduced but this came at the expense of MS production. Farmers need to exhibit caution when feeding fodder beet to lactating dairy cows to minimise the risk of adverse animal health effects. Feeding fodder beet allocations high enough to achieve significant environmental benefit is likely to compromise animal health and milk production. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]