Innovative Technology and Sustainable Development of Organic - 1.

Table 3. Mean results of environmental indicators for dairy farms with an automatic milking system
(AMS) and with a conventional milking system (CMS) in 2005 (SD in parentheses).
Indicator Dimension AMS CMS P value
Surplus N at farm level kg N/ha 110 (29) 66 (40) 0.02
Surplus P at farm level kg P/ha 8.8 (6.6) 3.4 (8.7) 0.16
Surplus N on grazing fields kg N/ha 92 (82) 166 (60) 0.05
Surplus N on mowing fields kg N/ha 148 (79) 53 (80) 0.03
Average field size ha 5 (1.1) 5.3 (3.8) 0.84
Plant species grazing fields No/ha 5.4 (1.3) 5.6 (2.1) 0.83
Plant species mowing fields No/ha 3.4 (2) 2.4 (1.1) 0.20
To explain our obtained results we used general characteristics of sampled farms as presented in Table
1 and parameters registered to capture grazing behaviour at AMS and CMS farms, which are presented
in Table 4. It was expected that AMS farms would have a higher N surplus on their grazing fields,
because of relatively few pastures around the barn suitable for grazing. However, the area of grassland
available for grazing per dairy cow did not differ between AMS and CMS farms (Table 1). The amount
of dry matter uptake from grazing, however, between AMS and CMS farms showed a tendency to be
different (P = 0.09, Table 1). This was supported by registration of the amount of time cows spent
grazing outside, which was higher for CMS than for AMS farms (P < 0.001). The fact that cows on
CMS farms spent more time grazing outside causes extra N excretion on grazing fields, which explains
the higher N surplus on fields used 100% for grazing. Consequently, on CMS farms, less excrement is
deposited in the barn, and therefore less manure is applied on mowing fields, explaining the lower N
surplus.
Table 4. Parameters registered to capture grazing behaviour.
Dimension Parameter AMS CMS P value
kg DM/LU Concentrates fed per LU 1)
7.3 (1.6) 6.3 (1.7) 0.2
kg dm/day Grass uptake from pasture 2)
5.1 (1.6) 6.9 (2.2) 0.09
h/year Grazing time
968 (198) 2,083 (788)