Nitrate leaching loss from urine patches is predicted using a number of variables including urine N concentration, number of urine patches produced, and urine patch size however, there is a lack of quantitative data on the variability of urination events. A study was conducted using two wintering systems at Ashley Dene, Lincoln, between June and July 2014. Wintering systems were either kale (KA) fed at an allowance of 14 kg DM/cow/day plus barley straw (3 kg DM/cow/day) (n=5), or fodder beet (FB) fed at an allowance of 8 kg DM/cow/day, plus ryegrass baleage (6 kg DM/cow/day) (n=7). Twelve pregnant, non-lactating Holstein- Friesian x Jersey cows were fitted with calibrated urine meters which measured volume and frequency of urination events. The meters were worn for 24-hour periods. A calibration equation was used to calculate urine patch coverage from measured urine patch areas in the field and urine volumes. There was large variation between animals for urination behaviour. Average urination volume was similar for KA and FB (2.37 L/event; P>0.1 SEM=0.29), however urination frequency (12 vs. 8 events/day; P<0.1 SEM=2.25) and daily total urine volume (30 vs. 18 litres; P<0.03, SEM=4.56) were greater for KA. Average urine patch area was also 1.8 times larger on KA than on FB (0.47 vs. 0.25 m2). This information will be used to help predict nitrate leaching losses from grazing systems.
Proceedings of the New Zealand Society of Animal Production, Volume 75, Dunedin, 84-88, 2015
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