|Construction costs are low per cow place. Operators must bend or crouch to perform most of the routine tasks on each cow. Milking efficiency is hindered by cows crossing the operator's work area. Cows in the exit passage are remote from the operator's control. Individual stalls allow individual attention during milking.|
|Construction costs are high per cow place. Operators can milk standing upright. Cows in the entry/exit passages are remote from the operator's control. Size of parlour and throughput are limited by the distance (2.5m) between udders. Individual stalls allow individual attention during milking. Food troughs can be easily reached and inspected by the operator.|
Milking machines were developed to meet demands for milking more cows more quickly using fewer people and less effort. Initially, this was achieved by the introduction of bucket units which were carried from cow to cow in traditional cowsheds or milking barns. Pipeline milking achieved considerable improvement in labour efficiency and reduction in manual lifting and carrying, but the major development was the change to parlours where the operators use stationary equipment to milk the cows as they pass through the installation during the course of milking.
|Cheaper, batch milking version of the tandem. Cows enter and leave through the stalls. Operator has control over cow entry/exit.|
|Cows stand in echelon formation at 30°–35° to the operator's pit with no division between cows. Distance between udders is reduced to 0.9 m. Operator has control over cow entry/exit Cows enter and leave in batches. Suitable for herds of 50–400 cows.|
|Three-sided herringbone with, consequently, smaller batches causing less delay from a slow milking cow. Comparative parlour performance capacity will require 20%–25% fewer units and stalls than the conventional herringbone|
Originally, rotary parlours were built for very large herds but more recently smaller ones have been designed to provide an alternative to the herringbone. As in the case of static parlours, the cows stand either side-by-side, ie, rotary abreast; head-to-tail ie, rotary tandem or in echelon formation, ie, rotary herringbone. During milking, cows walk onto a rotating platform singly with the operator standing at the point of entry to prepare the udders for milking and attach the teatcup clusters. The cows leave the platform when rotation brings them opposite the exit passage, the clusters having been removed automatically when milk flow ceased. High capital and maintenance costs, mechanical faults and the introduction of automation into static parlours have all contributed to a declining interest in rotaries. The most successful version is undoubtedly the rotary abreast which has no moving parts on the platform, the cows face inwards towards the centre and the operator is positioned at the circumference of the platform to control cow entry.
|Modification of the herringbone. Cows stand at right angles to the operator's pit, so that 3 cows occupy the length required for 2 in the herringbone. Cows must be milked through the back legs.|
|Least expensive rotary per cow place in terms of cost and space requirement. Cows face inwards separated by static tubular metal divisions. No moving parts on the platform. Operator standing at the platform perimeter can assist cow entry but cannot see the cows during rotation.|
|Most expensive per cow place in terms of cost and space requirement. Cows stand nose-to-tail in stalls circling the operators work area. Operator cannot assist cow entry but can see all cows easily during rotation.|
|Cows stand in echelon formation facing outwards around a central work area. Designs vary from simple yoke ties only on the platform to rotationally operated moving divisions which position the cows and allow entry and exit.|
|ONE MILKING UNIT PER TWO STALLS (½) Each milking unit is shared between two stalls. Comparatively short unit idle time of 0.2 mins. Slow milking cows can delay throughput.|
|ONE MILKING UNIT PER STALL (1/1) Each stall has a milking unit. More costly installation than ½. Throughout milking, about 50% of units will, on average, be idle with an average unit idle time of 1.2 mins. “Doubling-up” the number of units is equivalent to adding one more unit (eg. 5/10 to 10/106/12) in terms of available milking time per cow. Work routine time and feeding time per cow will be unaffected (in batch milking). Operators can select sequence of cluster attachment. More regular interval between udder preparation and cluster attachment.|
Other advantages of one unit per stall installations are that delays caused by slow milking cows can be minimised because the operator can select the sequence of cluster attachment to cater for known differences in the milking out times of cows; the interval between cow preparation and cluster attachment is likely to be more constant and, milk flow can be gravity assisted to pipelines below udder level.
The expense of doubling-up will achieve only a marginally improved throughput created by an increase in the available milking time per cow, improved flexibility in the use of the milking units and a work routine unimpeded by equipment hanging from the centre of the operator's work area.
When a new 1 stall per 1 unit installation is proposed in preference to a 1 unit per 2 stall alternative, these same marginal advantages are relevant together with a small saving in building space which occurs. For example a 10/10 herringbone requires approximately 1 m less length of building than the 6/12 equivalent.
|PARLOUR MILKING PERFORMANCE||WORK ROUTINE TIME||SIZE OF HERRINGBONE (units/stalls)|
|(cows/hour)||(mins/cows)||AVERAGE||AVAILABLE MILKING TIME (mins/cow|
MULTIPLE ACTIVITY CHART 4/8
MULTIPLE ACTIVITY CHART 8/8
- The maximum number of cows to be milked.
- The time available for milking at each end of the day, taking into account the other work to be done by those also doing the milkings.
- The number of operators milking together and the degree of mechanization and automation. Other things be ng equal, two operators should double the throughput but would require twice the parlour size.
1. The average milking-out time of the cows (MOT).
The milking-out time plus the time that units are not attached to cows (ie. unit idle time) is called the unit time (UT) and this prescribes the maximum number of cows that can be milked in one hour using one unit
Although milking times of individual cows vary considerably and will be affected by vacuum level and pulsation characteristics the most important factor influencing the average milking-out time of the cows in a herd is the average herd milk yield; the higher the average yield the longer the average MOT. The relationship between these factors is expressed as:
t = 0.21y + 2.75where t = herd milking time (mins/cow)
and y = average herd milk yield (litres/cow)
Thus, if the average yield of milk at a milking is 11 litres the average milking-out time will be 0.21 × 11 + 2.75 or about 5 minutes per cow.
2. The number of milking units (N) per operator.
Providing each milking unit is used to maximum efficiency the total number of cows milked per hour (P) will be the number of units (N) times the number that can be milked with one unit in an hour. Therefore for an installation:
There is a limit to the number of units that can be used effectively by one operator and if this is exceeded there will be an increase in the unit idle time or the units will be idle or left on the cows or hanging up after milk flow has ceased. This will increase the unit time (UT) and consequently lower performance (P).
3. The operator's work routine time (WRT).
This is the average time spent on the various tasks associated with milking each cow (ie. attaching and removing clusters, udder preparation, etc.). If the operator spends 2 minutes working on the routine tasks on each cow, the number of cows that can be milked in an hour cannot exceed 60å2 = 30 cows/hour. However, if the work routine time can be reduced to 1 minute the performance can be increased to 60 cows/hour providing the operator has a sufficient number of units. In most large parlours it is the work routine time that limits the performance.
Planning the correct operation of any milking installation is mainly a matter of adopting the correct work routine for the number of units to give the required performance. The relationships are shown in the Table for a herd which has an average unit time (ie. milking-out time plus machine idle time) of 6 minutes and calculated from P = N × 60 and
|Number of unites (N)||Unit Time (UT)|
|Work Routine Time (WRT)|
In cowshed milking, although the cows are stationary, operator time is spent walking from cow to cow, carrying udder preparation and milking equipment and transporting milk to the dairy. A substantial proportion of this time (25%) can be saved by placing milk cans, preparation equipment and spare milking machine buckets on a trolley which is moved as milking proceeds along the shed. If a pipeline is installed, milk can be transported direct from cow to dairy by vacuum, thereby allowing time to use additional milking units. Standard work routine times for the three alternatives are:
|Bucket milking machine :||2.0 mins/cow|
|Bucket milking machine with trolley :||1.5 "|
|Pipeline milking machine :||1.0 "|
Standard Work Routine Times Element
|Let in cow||0.2||Let in cow||0.1|
|Wash & dry udder||0.2||Wash & dry udder||0.2|
|Attach cluster||0.2||Attach cluster||0.2|
|Remove cluster||0.1||Automatic cluster removal||.|
|Disinfect teats||0.1||Automatic teatdisinfection||.|
|Let out cow||0.2||Let out cow||0.1|
|PLAN PARLOUR SELECTION||EXAMPLES|
|in a methodical way||Herd X||Herd Y|
|A.||Estimate the maximum number of cows that will be in milk||75||225|
|B.||Decide on the maximum duration of milking (hours)||1½||1½|
|C.||Calculate the required throughput A-B (cows/hour)||50||150|
|D.||Decide on the number of operators to be used||1||2|
|E.||Calculate the required performance C-D (cows/manhour)||50||75|
|F.||Estimate the maximum peak milk yield at a milking (kg or litres/cow)||20||14|
|G.||Determine (from E and F) the required parlour type and size (units and stalls) per operator||14/14|
|H.||Determine the available work routine time 60-E (mins/cow) and decide on the content of the work routine (from standard times) and the degree of automation required||1.2||0.8|
HERD A: All the year round calving policy; 12 hourly milking intervals. 20 litres/cow/day or 10 litres/cow/milking (mean peak yield)
HERD B: All cows calve within 3 months; 16 hour and 8 hour milking intervalsFor Herd B it is necessary to plan for the longer milking-out time per cow requirement which means more milking units than for Herd A to achieve the same performance.
30 litres/cow/day for first 100 days or 20 litres/cow at morning milking (mean peak yield)
30 litres/cow/day for first 100 days or 20 litres/cow at morning milking (mean peak yield)
(+0.2 mins machine idle time)
then Herd A requires 5 units (eg. 5/10) and Herd B requires 8 units (eg. 8/16).
Similar calculations have been tabulated to show the correct size of milking installation for a range of three milking performance. The Table shows the relationship between performance (P) work routine time (WRT) and static herringbone milking parlour capacity in terms of mean milk yield (kg/cow) up to which maximum performance is possible
|P cows per hour||WRT mins per cow||STATIC HERRINGBONES (units/stalls)|
|Mean milk yield (kg/cow) up to which maximum performance is possible *|
Two further examples will indicate how to use the Table. If a herd has an average peak yield of 16 litres/cow at a milking and a performance of 75 cows/hour is required the parlour should be either 14 units/14 stalls or 8 units/16 stalls. If 50 cows/hour is all that is required then a 10 unit/10 stall or 6 unit/12 stall parlour is sufficient. Obviously neither performances will be achieved unless the work routine times are 0.8 mins in the first example and 1.2 minutes in the second example. There are other general principles which can also be illustrated by the Table. To maintain performance when mean herd milk yields increase, or to increase performance at a constant herd milk yield, it is necessary to increase the number of units used. In order to increase performance, it is essential to reduce the work routine time per cow proportionally.