The physiological impact of the number of daylight hours on a sheep is remarkable. It has a proven influence on the weight gain of sheep. This can be managed by the type of housing you provide for your sheep.
We thank the ARC Institute for Agricultural Engineering in South Africa who made their manual on sheep production and facilities available to the readers of ProAgri Zambia.
Types of housing systems
Intensive housing systems in sheep production can be divided into feeding pen systems, or closed systems or as extensive housing systems in grazing camps.
Feeding pen systems
Three highly concentrated areas can be identified in a feeding pen, namely the feeding, resting and drinking areas. Normally the feeding crib is on top, the resting area in the middle and the drinking area at the bottom. This type of housing system is in general use in Southern Africa.
Figure 1 shows a typical feeding pen system. The roofed area of the system can vary in size, but as a directive, a shaded area of 0,3 m² to 0,75 m² per ewe or 1 m² per ewe with a lamb should be provided. The animals will normally remain in the roofed area or in the shade and the feeding troughs are usually placed under the roof. It can be expected that most of the manure will accumulate here, therefore the manure alley with gates are giving access to a tractor with a scraper or a telehandler for manure removal.
The moist and dirty conditions under the roof of a feeding pen can increase diseases. This is why a separate shade area should be provided in the middle of the pen. The feeding pens must be placed with the sloping position away from the feeding troughs and the roofed area to diminish problems with run-off water for this part. Run-off must preferably not flow from one pen to the other, as it can promote the spreading of disease. Trampling in front of feeding troughs can be prevented by placing a concrete slab of at least 80 mm wide in front of the trough.
If more than one row of feedlots have to be built, the rows should be placed four to six metres apart, so that a tractor and trailer can easily move between them. This spacing forms a connecting alley that leads to the handling facilities. The individual gates from each pen must seal off the alley completely.
Closed housing systems differ from the feeding pen system by limiting the movement of sheep to a minimum. This type of complex is not generally used in Southern Africa and requires a relatively large capital input. The benefit of the system is that it is more accurately controlled and managed. Features such as increased production can be achieved by positively utilising lengthened daylight hours. The closed system is generally used in Europe with its harsh winters. Two types of buildings are used, namely concrete floor buildings and slatted floor buildings. Although slatted floor buildings are more expensive than concrete floor buildings, twice as many animals can be housed in them as in concrete floor buildings.
The floor plans of some buildings can easily be changed by using loose-standing units for partitions. With this adaptation, the barn can be converted into lambing pens, slaughter lamb production pens or a shearing barn, which will mean more efficient utilisation of the facilities.
Under Southern African conditions, ram pens and lambing pens can be placed beneath a lean-to without any side cover. Materials that can be used for slatted floors include concrete, plastic, wood or expanded metal. Enclosed systems can also be used for specific animal groups, namely rams or ewes about to lamb.
Extensive grazing camps
Sheep are kept in these camps on grazing. The size of the camps will be determined by:
- The number of sheep (group size)
- The type and condition of the grazing
- The specific terrain layout
- The farmer’s management practices
- Soil type and rainfall (prevention of drainage problems and erosion)
No special facilities are necessary. A sheltered area (preferably a lean-to) and a shaded area must be provided if natural shelter such as trees and rock formations are not available. The sheep must have access to fresh water and feeding troughs with concentrated feed. Efficient fencing is also essential.
The influence of day length on slaughter lamb production
The influence of day length has repeatedly been proven in plant and animal production. The production of slaughter lambs is no exception. Intensive housing systems make it possible to implement this influence to the benefit of the producer.
Although all the physiological processes taking place during daylight lengthening have not been definitely determined, positive results were reached in experiments with the lengthening of daylight.
In an experiment during which two groups of slaughter lambs were exposed to 16 and 8 hours of daylight, it was proven that with the longer daylight length, lambs showed a better feed conversion rate and therefore needed less feed per unit for weight increase.
Table 1 shows the average benefit of a 16 hour daylight length compared to an 8 hour daylight length obtained from three different experiments.
The practical implementation of this influence had the following results for an American farmer in Table 2.
From these results and available research information, Schanbacher (1982) proposes that if controlled daylight length is applied in a production system, a 16 hour daylight length should be the objective.
Next month we shall look at artificial and natural ventilation and ventilation requirements.
Published with acknowledgement to the ARC Institute for Agricultural Engineering for the use of their Sheep Facilities Manual. Visit www.arc.agric.za for more information.