| Four configurations of a milking unit shown
in Figure 1 were calibrated with a portable flow simulator (O’Callaghan
and Gleeson, 2001) at a water flowrate of 4 l /min to give vacuum
levels during the b-phase of pulsation of 35, 38, 40 and 42
kPa at the apex of an artificial teat during simulated milking.
Simultaneous (4x1) and alternate (2x2) pulsation patterns and
two bores of long milk tubes (LMT) were used to establish these
differences in teat end vacuum (Table 1). The vacuum traces
recorded with the flow simulator for the four treatments are
shown in Figures 2 to 5 at a flow of 4 l/min.
Friesian cows (N=56) were milked in a 14 unit side-by-side parlour
in a Latin Square design experiment to establish the effect
of altering the teat-end vacuum levels on milking characteristics.
The system vacuum level for the mid-level milking plant was
set at 49 kPa. A pulsation rate of 60 Hz was used for the four
treatments and the “a”, “b”, “c”
and “d” values of the pulsation chamber waveform
were 12.0%, 56.2%, 11.3% and 20.5% respectively. One cluster
type fitted with wide bore tapered liners, a 150 ml claw and
a cluster weight of 3.16 kgs was used for the four treatments.
Milk yields and milk flow profiles were recorded automatically
with Dairymaster Weigh-all electronic milk meters. Clusters
were removed automatically at a milk flow-rate of 0.2 kg/min.
Milking time was computed as the time interval from cluster
application to when the milk flow reached 0.2 kgs/min. Pre-milking
preparation consisted of washing teats with warm running water
and drying with individual paper towels.
Figure 1. X-section of
milking unit for milking tests
Table 1. Details of milking treatments
| Treatment |
Pulsation Pattern |
Bore of LMT (mm) |
Vacuum at 4 l/min (kPa) |
| T1 |
4x1 |
16.0 |
42 |
| T2 |
4x1 |
13.5 |
40 |
| T3 |
2x2 |
16.0 |
38 |
| T4 |
2x2 |
13.5 |
35 |
Figure 2. Vacuum traces
of pulsation chamber vacuum, claw vacuum and teat end vacuum
with a 16mm bore LMT and simultaneous (4x1) pulsation.
Figure 3. Vacuum traces
of pulsation chamber vacuum, claw vacuum and teat end vacuum
with a 13.5 mm bore LMT and simultaneous (4x1) pulsation.
Figure 4. Vacuum traces
of pulsation chamber vacuum, claw vacuum and teat end vacuum
with a 16 mm bore LMT and alternate (2x2) pulsation.
Figure 5. Vacuum traces
of pulsation chamber vacuum, claw vacuum and teat end vacuum
with a 13.5 mm bore LMT and alternate (2x2) pulsation.
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