Shearing shed design - sheep storage and movement

Introduction

The sheep storage area of a shearing shed consists of the shed entrance and the holding, filling and catching pens. Good design of these components is important for efficient sheep movement and to minimise labour requirements.

Entrance

Allow plenty of room for sheep to enter the shed. A wide opening into the sheep area is much better than a narrow one because several sheep can move side by side.

Most new shearing sheds are built off the ground and have a ramp leading to the shed entrance which should be 2.4 to 3 m wide for rapid filling of the shed area.The entrance ramp can have a maximum gradient of 1 in 3. The ramp floor may be constructed of wood or concrete, and sides should be screened so that the sheep cannot see out. It is important that sheep cannot see down through the ramp.

A ramp can be replaced by steps. Stepped entrances may be useful in higher rainfall areas where a slippery ramp surface can be a problem for both sheep and shed workers. New Zealand experience indicates that steps of 300 mm wide × 130 mm high are suitable. The steps should continue up to the wall of the shed with no external horizontal landing.

Three types of ramps have been successful. These are:

ramps at right angles to the shed wall containing the entry;
curved ramps;
ramps which run along the side of the shed before turning at right angles into the shed via an external landing.

A walkway along the side of the ramp provides easy access for workers and dogs when sheep are being run into the shed. Sliding doors are most suitable for the sheep entrance. Having a door hung on the outside of the shed with flashing over the top for weather-proofing allows a sliding gate to be fitted on the inside of the shed. This allows the entry door to remain open to improve ventilation and lighting.

Holding pens

Ideally, pen capacities throughout the shed should be in multiples of catching pens. If the catching pen holds 22–24 full wool sheep, then the forcing pen should hold 22–24 or 44–48 full wool sheep, and holding pens 88–96 full wool sheep.

When calculating the area required for sheep storage, allow 2.7 full wool adult sheep per square metre.

The total area for sheep storage in a shearing shed depends on the number of shearing stands, the month of shearing and the expected number of wet days during shearing.

In most areas of New South Wales, undercover holding space should be sufficient for at least 1 day’s shearing without including the catching pens. This may be extended to 2 days in the high-rainfall areas or where shearing is undertaken during wetter months. Nearby machinery storage, hay sheds or skillions added to the sheltered side of the shearing shed can also be used as extra sheep-holding areas.

Sheep-holding pens that each hold 90–100 full wool sheep are considered adequate. An area of 33–37 m² is required to hold this number of sheep.

If pens hold more than 100 full wool sheep there can be problems with sheep packing and smothering. This is particularly the case with young sheep.

Filling pens

Pens adjacent to the catching pens are called the ‘filling pens’. It is from here that sheep move into the catching pens. These pens are also used as general sheep-holding pens. Well-planned filling pens are much better to work in.

Traditionally, the filling pen has consisted of a rectangular pen behind catching pens. In shearing sheds with front-fill catching pens the fill pens are beside each catching pen.

Usually filling pens hold 22–24 or 44–48 full wool sheep; that is, equal to or double the number held in each catching pen. A maximum of 17 m² should be ample forcing area for each catching pen. This ensures that the catching pen will need to be filled only once in each shearing run.

Catching pens

The two main considerations in the design and construction of catching pens are ease of penning up sheep and ease of catching for the shearer.

Penning-up is easier if each catching pen holds a minimum of half a run, say 22–24 sheep.

The distance between shearing stands is determined by the catching pen width. A minimum of 1.8 metres between stands is recommended even though the Pastoral Award allows a smaller distance. When designing a shed, remember that the capacity of the catching pens will determine the width between stands.

Sheep density can be higher in the catching pens. As a guide, allow 3.5 full wool adult sheep per square metre of catching pen space. A pen 2.0 m wide by 3.0 m deep should hold 22 full wool adult sheep.

Shearers usually prefer to have individual catching pens. Where two shearers do catch out of the one pen, a commonly used size is 3.5 m wide by 3 m deep. Double catching pens may need filling more often than single pens.

The main types of catching pens are:

back-fill pen
modified back-fill pen
front-fill pen
combined catch/fill pen
race-fill pen

Back-fill catching pen

Conventional back-fill catching pens are usually 2.1 m wide by 3 m deep for a single pen, and 3.5 m by 3.0 m where double pens are installed. Traditionally a back-fill system has a 1.2 m wide entrance gate. Some work well, but most are the curse of shed workers.

Efficiency may be improved by installing a lift swing or slide swing gate to widen the opening between the catching and filling pens.

Modified back-fill catching pen

The filling problems of the conventional back-fill catching pen can be overcome by installing a modified back-fill system. This involves fitting a lift swing gate between the catch and fill pen. This gate is the full width of the pens and, for best results, the dimensions of both the catching and filling pens are the same.

To fill the catching pen, the lift-swing gate is raised and swung over the sheep in the fill pen before being lowered and used as a force if necessary. The advantage of this system is that the sheep are moving forward into the catching pen as a group rather than singly as in the conventional back-fill system.

Front-fill catching pens

Front-fill catching pen systems require each shearing stand to have two pens—a catching pen and filling pen, both of which are adjacent to the board. Where three or more stands are required, a curved shearing board design is usually installed to keep the shed width to a minimum.

Figure 3. Front-fill catching pen

Sheep move from the filling pen through a slide swing gate 1.2 m wide, situated in the front corner of the catching pen.

Sheep fill from the front corner and run away from the noise on the shearing board, back towards the other sheep in the holding pens. There should be a holding pen behind or beside each catching pen to encourage sheep movement.

It is possible to install front-fill systems into a straight-board shearing shed of up to four stands. Some producers prefer this design because the costs and building problems associated with curved shearing boards are avoided. These designs have double catching pens.

Combined catching/filling pens

This system combines the function of both the catching and filling pens of other systems.

The sheep for each stand are confined in a single pen. When this pen is almost empty a lift swing gate which forms the side of the pen is closed so that it is parallel to the shearing board, confining the few remaining sheep near the catching pen door.

The rear section of the original pen is then filled and the lift swing gate raised and swung back to its earlier position.

This type of pen is usually larger than a single catching pen, but smaller than the combined area of separate catching and filling pens.

Race-fill catching pen

The race-fill system suits a catching pen with dimensions of 2.5 m wide by 3 m deep. These dimensions allow for the intrusion of the top of the chute without affecting the race-fill function. Race-fill catching pens can be incorporated into return race let-go systems.

Figure 5. Race-fill system using shorn sheep return race

The race is usually 600 mm wide and 1500 mm long. In some instances, screened panels may be needed to restrict the vision of the sheep. A suitable arrangement is shown in the diagram.

To fill the catching pen, the shed worker starts the sheep up the race from the filling pen and keeps the others following on. A ‘prodder’ made from 1500 mm of 40 mm diameter polypipe is ideal for keeping sheep moving through a race-fill system.

The sheep run up the race and, on reaching the end, turn and run to the far back corner, drawing the others after them. The theory is that sheep can be run into the catching pen at any time.

Compared with all other systems, except the conventional back-fill, race-fill is least favoured.

Grating

A grating floor is used in the pen area of a shearing shed to allow sheep droppings to pass through and maintain sheep in the cleanest possible condition for shearing. In conventional sheds with chutes, the grating height is commonly 1.2 m or more above ground. This readily allows cleaning of the underfloor area. In sheds close to ground level, the battens should be on removable frames to make manure removal easy.

Grating direction affects the flow of sheep through the shed. The direction is particularly important at the shed entrance. Grating is best laid at right angles to the ‘flow’ of the sheep so the sheep see less light underneath the floor and are less likely to baulk. An alternative in small sheds is to lay the grating diagonally across the pen area.

Where sheep flow is in the same direction as the grating, extending the wall cladding to ground level will improve sheep flow by reducing or eliminating light beneath the grating.

Lay catching pen grating at right angles to the shearing board. This can make it safer and easier for shearers to catch and drag sheep to the shearing board.

Timber grating

Grating is usually made from timber of around 40 mm × 30 mm for hardwood battens. Where pine grating is used 40 mm × 35 mm batten size is recommended. All grating is virtually self-cleaning if laid with 15 mm gaps using seasoned timber. If ‘green’ timber is used, allowance must be made for shrinkage which occurs as the timber dries out.

Bevelled battens are preferred in areas where the grating is likely to get clogged up. These are 50 mm × 40 mm and tapered back on the underside by 10 mm. Bevelled battens can be sawn from timber 100 mm × 40 mm by one angled saw cut.

When bevelled grating is laid, the bevel side should face away from the oncoming sheep at right angles to the main sheep flow. This reduces what the sheep can see under the floor.

Woven wire or metal mesh grating

Woven wire or metal mesh grating is an alternative to timber. The mesh is manufactured in sheets that can be easily installed on either timber or metal flooring joists.

Particular attention should be given to minimising the amount of underfloor light when fitting mesh grating in a shearing shed. At the same time the pen area of the shed must be well lit from above floor level.

Noise levels may be higher in sheds with metal grating, as mesh flooring can develop a characteristic ‘drum’ as sheep move around.

Polypropylene grating

Sections of grating made from hard-wearing polypropylene can be used for flooring in the pen area. The high-load-bearing structure and modular interlocking system make this type of grating easy to install. The high cost of polypropylene grating is a major consideration.

Construction

In the pen area, pier spacings at 1800 mm centres give a satisfactory weight distribution on each supporting pier. These piers are constructed from 100 mm × 100 mm red gum or reinforced concrete. Alternatively, 50 mm (internal diameter) galvanised pipe piers, welded to 150 mm lengths of 76 × 76 × 6.5 mm angle iron, can be used to support the bearers and joists. It is recommended that piers be either concreted into the ground or set on sole plates. Where galvanised pipe is used it should be protected from the corrosive effects of damp manure near ground level.

Grating is laid on hardwood bearers 100 mm × 75 mm and 100 mm × 50 mm hardwood joists (both stress grade F8) at 450 mm centres throughout the sheep-handling area. The bearers and joists should be continuous over two or more spans.

Gates

The ease with which sheep can be moved around the pen area of a shearing shed can also be influenced by the position and type of gate installed. Gates that are easy to operate and wide enough to let sheep move through as a group will assist with sheep movement.

The appropriate gate to install will depend on the internal design of the shed and the gate’s location. Conventional swing gates in the main are unsatisfactory because of the difficulty of opening them into a pen full of sheep. A number of gates have been developed to overcome this problem.

Lift swing gates

Lift swing gates may operate like conventional swing gates, but can also be raised and lowered on the gate post. This action is used to lift and swing the gate above and across tightly packed sheep. The gate is then lowered and used in the conventional manner to help move the sheep into the next pen. A lift swing gate made to the full width of the opening between two pens can add greatly to efficient sheep flow.

Lift swing gates can be constructed from timber or steel piping. A good working mechanism is needed if the gates are to operate successfully. Some designs use pulleys and a counterbalance weight to assist operation. Others have a simple locking device to hold the gate in position when it is raised. A small roller bearing placed in the centre of both top and bottom hinges will reduce friction and allow continuous smooth up-and-down movement.

The lift swing system can be used in most gateways in the sheep-holding area of a shed. A lift swing gate can also be used as the entire back panel of the catching pen. When installed in the catching pen these gates are the full width of the pen.

Slide swing gate

This gate is designed to both slide and swing. The gate is mounted in a pivoting stirrup through which the frame can slide. Because the stirrup is pivoted, the gate can also swing. The practical limit to the width of this type of gate is about 2.5 m.

To operate a slide swing gate, slide the frame through its stirrup and along the fence. The gate is then closed from behind the sheep as a normal swing gate. The gates need to be made slightly wider than the gate opening to allow for the pivoting hinge.

Tip swing gate

This gate has a centre pivot hinge mechanism. To operate, the gate frame is tipped back along the fence and then closed like a conventional swing gate. It is suited to a gate width of up to 1.8 m.

Lift gates

Designed to operate by a simple up-and-down movement, lift gates are also known as the guillotine-type gate. They can be installed in gateways too wide for lift swing gates or where the forcing capability of lift swing, slide swing, tip swing or conventional gates is not required.

Some designs use pulleys and counterbalance weights to assist the operation.

It is essential that the lift gate runs true in its frame. Otherwise it may jam and be difficult to operate. This is important where wide lift gates are installed.

Gate catches

Selection of gate catches depends largely on the materials used to build gates and gate posts. Catches for timber gates are usually not suitable for gates made from pipe. A good catch is one that is reliable, allows the gate to be effectively secured, and can be operated quickly. It should require little or no maintenance and allow the gate to swing both ways if required.

The following types of gate catches are suitable for installation in shearing sheds:

chain and slot
sliding bolt
pin and ring
tongue and slot
chain and loop
chain and hook

The ‘chain and slot’ type of gate catch is easy to make and operate. It is also probably the most reliable and least expensive type of catch. The chain should be made from links at least 25 mm long and the slot should have a width at least double the width of the chain links.

Use about 200 mm of chain, and adequate slots can be made with 100 mm of 10 mm diameter rod welded close to the frame of the gate. When the gate is secured, the chain passes below, then over and through the slot.

Lighting

Lighting is a vital component of efficient sheep flow within the shearing shed. See Agfact A3.E.4 Shearing shed design—lighting and ventilation.

Further information

For further information on shearing shed design, see the following publications:

Acknowledgment

This Agfact was adapted in part from the Australian Wool Corporation publication Wool Harvesting Notes.