Zambia is a paradise for a wide variety of external parasites. Dipping your animals in this environment is crucial if you want to continue farming.
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.
Two different opinions exist regarding the placing of the dip facility relative to the rest of the facility. The first is that the dip should be placed in the normal handling route in order to utilise the habit-forming characteristic of the sheep. The second opinion is to place the dip facility outside the normal handling route, because of the negative association the sheep can develop with the dip process and therefore can delay the handling tempo. This will of course only occur in a system where sheep are not handled often.
A distinction is made between walk-in/walk-out dips and those dips where the handler places the sheep in the dip and it walks out by itself. The first type requires little energy from the handler and will be the automatic choice from a labour point of view. Figures 1 to 3 show typical dip facilities.
A further distinction is made between oblong, round, or spray-dips. The choice of a type of dip is that of the manager or handler.
Round dips are usually the type where the sheep has to be lowered into the dip. The round dip has the advantage that during dipping for mange – when they have to lie in the dip mixture for one whole minute – they can be forced to swim around in the tank for that specific time. A further advantage of the round dip is that the handler does not have to move over a long distance to control the sheep in the dip.
Longitudinal dipping tanks are usually the walk-in/walk-out type and have the advantages that the dipping process is usually completed quicker than with the round dip and that it is less labour intensive. Note that the top width of the dip is 500 mm for smaller breeds to 600 mm for larger breeds. Sheep must not be able to turn around in a dip.
Where the dip is placed alongside the normal handling route, the same reception pen used for the crush can be used. If the dip is placed away from the normal handling route, a reception pen must be placed in front of the dip.
A gathering pen in which the handler does not have to move more than two metres must be provided adjacent to the round lowering-in type dip. Spray-dips are not used for sheep on a large scale, because of the poor wetting of sheep, especially those with a long fleece.
A foot bath can also be incorporated into the facility to treat foot-related diseases.
Figure 4 shows the dimensions of such a foot bath. The foot bath must be at least 4 metres long, 500 mm wide and 300 mm deep. The first 600 mm of the rinsing bath can have a non-slip, but smooth, concrete surface. The rest of the foot bath and the treatment bath have a corrugated finish, in order to force the claws of the sheep open for more effective treatment, for example formalin treatment.
At least two dripping pens are placed at the exit of the dip where sheep stand for about 10 minutes so that excess water can drip off and run back into the dip. A surface of 0,5 m²/sheep must be provided for dripping pens. The floor of the dripping pen is usually of concrete with a coarse finish to prevent sheep from slipping and falling. The floor has a slope of 1:30 in the direction of the dip so that dripping water can be drained back into the dip.
The influence of sheep behaviour on the design of handling facilities
Important objectives in the design of facilities such as shearing sheds and handling facilities must include comfort and simplicity for the handler. These objectives cannot be met completely without taking sheep’s behavioural characteristics into consideration.
Like all other animals, sheep will resist movement if it is uncomfortable, or if they sense danger. These danger impulses hamper and delay handling, which is detrimental to the effectiveness of the system.
Handling is negatively influenced by the following (also see figure 5):
- Noise, for example machinery in the workroom, tractors, barking dogs, et cetera.
- Obstruction of the sheep’s view.
- Other activities which distract the sheep’s attention.
- “Danger”, for example a handler standing at the end of the crush or dark shadows in the alley.
By considering the following, designs may possibly be improved:
- Sheep would rather move along the contour than on a grade or off-grade. Where the terrain has a gradient of more than 3%, crushes must, where possible, be placed on the contour. If this is not possible, try to keep the largest portion of the movement upwards.
- Movement is better when sheep are moved away from buildings in the direction of the veld than vice versa. Activities must therefore rather take place in a direction away from buildings.
- Try to have the direction of movement in a crush from south to north. Although it does not influence the movement of sheep directly, it does however simplify the task of the handler, because his back now faces the sun.
- Hudson and Hitchcock (1978) proved that sheep move faster in long, straight alleys than around bends. What is, however, important here, is that the sheep will have a clear, unobstructed view of the exit. When sheep move in single file, there is not much difference between the round or straight crush.
- The round crush has the advantage that, although the sheep can see the handler, they do not move directly towards him.
- Sheep get used to and learn a path very easily. In order to utilise this characteristic, try to let the sheep always follow the same route through the handling complex, independent from the activity.
- Sheep will move slower or will even stand still when they pass another group of still-standing sheep. It will therefore be beneficial to close the sides of the alley. In the case of a semi-round alley it is not always desirable to close the sides, because the sheep’s view to the exit is then limited and a feeling of a dead-end is created.
- Sheep are very sensitive to shadows, especially if the shadow moves, because they see it as a threat. An experiment with nine different groups of sheep showed that eight of the nine groups chose an alternative route rather than move over the shadow. When sheep must enter a building, resistance against this movement can be expected.
- Covering material of the crush must preferably not be made of corrugated iron due to the potential noise that it may make when it is for instance kicked by a sheep.
Next month we shall look at typical lay-out of handling complexes. Published with acknowledgement to the ARC – Agricultural Engineering for the use of their Sheep Facilities Manual.
Visit www.arc.agric.za for more information.