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The effect of sward type, grass only (GO) or grass white clover (GWc), on lactating dairy cow feeding behaviour, herbage depletion rate and rumen function was investigated in rotationally strip-grazed swards at a daily herbage allowance of 17 kg dry matter (DM)/cow/day, in two experiments. In 2011, eight rumen-cannulated cows were blocked into two groups and allocated to each sward type for a 14-day period in a change-over design (2 sward types×2 periods) on three occasions: late spring, summer, and autumn. Feeding behaviour, rumen pH and rumen volatile fatty acids and ammonia contents were measured. Following a continuous design, in 2012 feeding behaviour and herbage depletion rate measurements were undertaken at similar times to those in 2011 over 2–3 weeks in late spring, summer and autumn. Twenty-six (spring) and 36 (summer and autumn) cows were used. Grazing sward height (GSH) was measured five times/day. The percentage of grazed vegetative units, and the extended tiller height, free leaf lamina, tiller DM weight and tiller leaf DM weight of perennial ryegrass (ryegrass) tillers were estimated four times/day. During late spring, summer and autumn, sward white clover content (DM basis) was 7.5%, 8.8% and 30.9%, respectively, in 2011, and 18.0%, 29.7% and 30.6%, respectively, in 2012. In 2011 cows had similar grazing times on both sward types. Cows on GWc spent less time ruminating than cows on GO. Cows had similar total volatile fatty acids on both swards but the isoacids and d -lactic acid percentages, ammonia content and rumen pH were higher in autumn for cows grazing GWc. In 2012, cows on GWc grazed for longer in late spring, ruminated for less time in summer and for less time at night in autumn compared to cows grazing the GO sward. Both sward types had similar post-grazing sward heights and sward height depletion rates, except during morning grazing in autumn, when GWc had a greater sward height depletion rate. A similar percentage of grazed ryegrass tillers was observed between sward types, but the percentage of ryegrass grazed was greater than the percentage of white clover grazed in the GWc swards. The ryegrass tillers in the GWc swards were smaller than those in the GO swards but had similar depletion rates. The GWc swards influenced cow feeding behaviour and rumen characteristics with increased effect in autumn because of an increase in white clover content and a decrease in ryegrass quality.

The excretion of urine by dairy cows provides a source of nitrogen (N) to pasture. Excess N from urine patches can be lost through nitrate (NO 3 − ) leaching and nitrous oxide (N 2 O) emissions. Dicyandiamide (DCD) inhibits nitrification in the soil and is usually applied to the pasture by blanket spreading the entire field. This study assessed the potential of pulse-dosing cows with DCD so that the DCD will be excreted in the urine and deposited directly onto the urine patches. The objective of this study was to measure the recovery of DCD in urine and faeces and to assess the effects of DCD on rumen and blood metabolites and diet digestibility. Eight non-lactating Holstein–Friesian dairy cows fitted with rumen cannulae were assigned to two treatments in a Latin square design over two periods. The two treatments used were (1) control (CON) consisting of 500 ml distilled water and (2) DCD consisting of 0.1 g DCD per kg liveweight (LW) suspended in 500 ml distilled water. Both treatments were pulse-dosed into the rumen daily for 6 days with half the volume dosed in the morning and the remainder in the afternoon. The administration of DCD into the rumen had no effect on rumen and blood metabolites, and diet digestibility when compared to the control treatment, as all were not significantly different from the control treatment and were within the normal biological range. During 6 days of dosing with DCD the average recovery of the dosed DCD in urine was 82.3%, with a further 2.1% recovered in the faeces. No DCD was recovered in the urine and faeces 10 days following the cessation of dosing. These results could provide the basis for a novel mitigation strategy to reduce NO 3 − leaching and N 2 O emissions from urine patches in grazed grassland.