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Sheep farming made easy – Part 14: Elements of the shearing shed complex

The shearing shed complex can be divided into three clearly identifiable areas based on the activities performed in these areas. These areas are the:

  • Holding area
  • Shearing area
  • Wool handling area

We thank the ARC Agricultural Engineering in South Africa for making their manual on sheep production and facilities available to the readers of ProAgri Zambia.

The shearing shed can also include the following:

  • Storeroom for bale bags, shears, parts, et cetera.
  • Office for record-keeping systems, first aid equipment, medicine, kettles, et cetera.
  • Toilet facilities and showers. If these facilities are placed too far away from the building, unnecessary time is wasted.
Figure 1: Typical layout and minimum dimensions of a shearing shed.

Holding area

The holding or keeping area of the shearing complex includes a shed, filling pens, gathering pens and collecting pens. It is in this part of the complex where the most sheep movement takes place and the shearing tempo will be negatively influenced if shearers have to wait for the sheep. The influence of sheep behaviour has already been discussed in a previous edition and is also applicable here.

The design principle applicable on these areas will be to include all characteristics and factors which promote the required movement of sheep with the least time and effort for the handler.

The entrance:

The entrance to the shearing shed is important as it can have a great influence on the resistance against movement. The following must be considered in the design of the entrance:

  • The floor surface of the entrance must be durable, preferably of concrete and non-slip.
  • The entrance must be wide enough so that more than one sheep at a time can enter side by side for easier movement. It must however not be so wide that it becomes difficult for the handler to control the sheep. A minimum practical width is approximately 1,5 m with a maximum of 2,5 to 3,0 m.
  • Where the shearing level is higher than the wool handling level, it will be necessary to use a ramp. The slope of the ramp must preferably not exceed 20° (1:3).
  • The sides of the ramp must preferably be covered with a non-transparent material, because the height may hamper the flow of the sheep.
  • The ramp may be straight or at a 90° angle into the building, as shown in Figure 2. In the case of a straight ramp, the slope must preferably be into the entrance of the barn, because a flat surface in front of the entrance causes hesitation to move into the building. A flat level in the case of a 90° ramp does not only simplify construction, but because the sheep disappear around the corner, it helps to lure the sheep that follow.
Figure 2: Typical entrances to a shearing shed.

  
In cases where space for the entrance is limited, steps can be used instead of a ramp. The best dimensions for the steps are 130 mm high and 300 mm deep.

Lighting:

As discussed, shadows and lighting will influence the movement of sheep. It can be expected that the sheep will resist if the interior of the building is darker than outside.

Sufficient windows and visible decoy sheep at the end of the alley can solve the problem. The minimum requirements, as prescribed, must also be adhered to.

Figure 3: Recommended dimensions for entrance steps.

The floor:

In some shearing sheds, there is a height difference between the shearing level and the wool handling level. The height is determined by the minimum height necessary for the sheep to pass through underneath the floor from the building and a comfortable height to make manure removal possible. A practical height, in most cases, will be 1 200 mm. Where the height is less, for example 800 mm, the manure removal can be simplified by building the slatted floor as removable panels. The floor panels are then lifted, the manure removed, and the panels replaced.

The slats are normally made from hardwood, but plastic and expanded metal have also been used successfully.

Figure 4a: Concrete sliding chute for heights over 1 m.

Pen sizes and capacity:

The size and capacity of the gathering pens and filling pens depend on the daily flow necessary and on the typical weather conditions. The daily flow can be calculated by multiplying the number of shearing points by the average number of sheep sheared per shearer per day.

The filling pens must hold sufficient sheep for half a day’s shearing during warm conditions. This will allow the sheep to cool down before shearing. When unpleasantly wet or cold conditions prevail during the shearing period, the filling pens must hold sufficient sheep to provide the shearers with sheep for a day or a day and a half. A typical occupation of the filling pens is 2,5 sheep/m² or 0,4 m² per sheep.

The gathering pens must be small enough to prevent the shearer from having to struggle to catch the next sheep. A maximum depth is approximately 3 m. Because sheep have difficulty in moving as they come closer to the shearing activities – probably because of the noise and movement – the gathering pen should not be filled too often. A general directive is to keep enough sheep for an hour’s shearing. Well trained and experienced shearers can shear 18 to 20 sheep per hour. The occupation of the gathering pens can be increased to 2,7 to 2,8 sheep/m², or approximately 0,36 m²/sheep. The gathering pen will therefore have to be 2,5 m wide to hold 20 sheep. Smaller gathering pens can also be used, and a typical dimension of 2 x 2 m is in general use.

Feedback alleys or sliding chutes:

The feedback alley is used for keeping a record of the number of sheep sheared and must provide enough room for a two-hour shearing period, with an occupation of 3,5 sheep/m² or 0,3 m²/sheep.

The feedback alleys have the disadvantage that the sheared sheep must also be kept on the slatted floor and this means that a larger surface is required, which increases costs. A further disadvantage is that different groups of sheep move to and from the shearing area, an aspect which hampers handling.

Sliding chutes can be provided with trapdoors on the shearing level or can be extended so that the sides are higher than the floor. Typical materials for this use are sheet metal or concrete and it must be as smooth as possible. If sheet metal is used, the bottom ridge rests on a brick or concrete wall of ± 150 mm high to prevent corrosion of the steel. Figures 4a and 4b show concrete sliding chutes for heights up to 1 m and higher than 1 m. The partitions of the pens in the shearing shed can be made of wood or steel pipes. Figure 5 shows typical dimensions. In less intensive systems, especially with feedback alley sheds, the partitions can be removable units so that alternative lay-outs are possible.

By using the same shed for shearing, feeding pens or lambing pens, the utilisation period of the shearing shed can be extended beneficially.

Partitions between the gathering pen and the shearing shed must preferably be non-transparent and approximately 1,5 m high. Sheep are then usually more tranquil, because they cannot see the activities on the shearing floor. This makes the handler’s task easier.

Figure 5: Partition construction detail.

The shearing area

The shearing area is that area where the shearer, sheep and wool are in simultaneous contact. Lighting, ventilation and available space are the most important factors which influence the effectiveness of the shearer. The shearing floor is conventionally a long, straight, wooden floor on which the shearing action takes place. Typical dimensions of the shearing floor are shown in Figure 6.

In more modern shearing sheds, arched shearing floors are used. (See figure 7). The greatest advantage of this is that the fleece-handlers are central to all the shearing points and walking distances are minimised. The number of shearing points determines the width of the structure. By using an arched floor, more shearing points can be installed for the same structure width, which is more cost effective.

The typical area used by the shearer during the shearing process, as well as other proportions, are shown in Figure 8.

Figure 6: Elevation of shearing shed to show floor heights.

Wool handling area

The third activity, which is also the last, is the wool handling area. This is the area where wool is collected, graded, prepared, baled, stored and dispatched. This is also the area where the potential income from the wool is determined. Poor practices and/or equipment can cause great losses. In contrast to the other handling activities, where speed and simplicity are important, the design principles for the wool handling area depend on well-organised and disciplined actions.

Good facilities, high flow-through and simple handling of the sheep cannot compensate for negligent work in the wool handling area.

After a sheep is sheared and the shearer has gone to catch his next sheep, the fleece is removed from the shearing floor and thrown open on the skirting table. The wool handling tables must be as close as possible to the shearing floor, without being constrictive on movement routes. Urine-stained, dirty wool and pieces are taken to the lock table and pieces table. The classifier and the skirter remove all skirting and double-cut wool which are taken to the pieces tables and lock tables. The fleece is divided on the fleece lines and placed into wool bins. Wool bins must preferably be mobile for ease of movement. The filled wool bins are now taken to the wool press where the bales of wool are stored before being sold. (Equipment such as wool tables, wool bins and wool presses will be discussed in a future edition.)

Figure 7: A diagram of arched shearing floor layouts.

Wool production and storage space

A storage space of 0,0075 m²/sheep is necessary for storage of wool bales. For the calculation, a wool production of five kg per sheep, a bale mass of 170 kg and double layer storage is accepted.

Next month we shall look at general equipment like water and feed troughs, shade and fences.

Figure 8: Typical space requirements of shearer in relative distances.

Published with acknowledgement to the ARC Agricultural Engineering for the use of their Sheep Facilities Manual. Visit www.arc.agric.za for more information.

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