|Section 1.2||Basis of Design|
|Section 1.4||Location and Site|
|Section 1.5||Description of Modules|
|Section 1.6||Alternative Energy Sources|
STANDARD PLANS FOR A SMALL ABATTOIR
AND MEAT MARKET
SECTION 1 : BACKGROUND
This report presents designs, specifications, and schedule of quantities for an abattoir and meat market suitable for small communities in the South Pacific region. The design could however be utilized by small communities in other developing countries, although some modifications to suit changed local conditions may be required.
Provision is made in the basic design for slaughter of all species, viz. cattle (or buffalo), sheep, goats and pigs though because of space limitations, concurrent slaughter of different species is not possible. The abattoir capacity will be dependent on the mix of animals being slaughtered. Daily throughputs of approximately 5 large stock (eg cattle) or 50 small stock (sheep, goats or pigs) or a combination thereof represent a practical maximum for this design.
The design has been based on “Guidelines on Small Slaughterhouses and Meat Hygiene for Developing Countries” WHO publication VPH 83.56, with modifications to take account of the likely mix of stock in South Pacific countries.
The facilities are divided into a series of ‘modules’ which can be combined as required to suit a particular location.
The following modules are included:
These modules and the options available within the individual modules are described in Section 1.5
A possible overall abattoir layout based on the above modules is shown in Drawing 1.
This layout shows a typical arrangement for a facility designed to handle beef, small ruminants and pigs with the main emphasis placed on small stock. Modifications for a larger beef kill and/or the elimination of pig slaughter (eg for Muslim communities) are possible.
The following items which are necessary to the functioning of the abattoir have not been detailed in these standard plans.
These should be provided in accordance with local practice based on locally available materials.
A minimum site area of 1800 square metres will be required to accommodate all modules. The abattoir layout presented is based on a rectangular site 30 metres by 60 metres.
Only general guidance as to location and siting can be given in a report such as this. Points to consider in selecting a suitable site are listed below. In practice compromises will inevitably be needed when selecting a site.
In presenting this check list it has been assumed that a general locality for the abattoir will already have been established based on sources of stock supply, location of markets, and taking into account transport methods and infrastructure availability.
Distance from Urban Development
The abattoir should not be located close to dwellings, schools, churches and other public or commercial buildings due to possible nuisance from noise, smell congestion etc. Likely future commercial and residential developments should also be taken into account.
The site should be accessible from a permanent road to allow ready transport of both livestock and meat.
An adequate water supply is essential. While mains water is to be preferred, well or bore water will also be suitable provided the water meets drinking water standards.
Quantities of 1000 litres per large animal 100 litres per small ruminant 450 litres per pig are desirable.1
In some areas it may be necessary to rely on rainwater collected from the abattoir roofs. (Under these circumstances water usage will need to be much lower than given above and ‘dry’ slaughter systems should be adopted.2. The use of rainwater should however be avoided if at all possible due to the limited supply available from this source.
1 Refer “FAO Design of Model Slaughterhouses for Rural Areas” Section 2.4
2 Refer WHO VPH/83.56 Section 5.5
The effluent disposal schemes presented in this report are based on subsurface irrigation and soakage. Such systems are generally lower in cost and easier to operate than other alternatives. The site should therefore be free draining and not subject to waterlogging or flooding. Land used for subsurface irrigation need not necessarily be within the abattoir boundary although control over cropping operations above subsurface irrigation trenches would be essential.
Section 2.2 details foundation conditions required for the buildings together with details of simple tests for suitability.
Solid Waste Disposal
There should be sufficient space available to bury inedible wastes and condemned animals and provide for compost stacks, hide drying frames etc.
Connection to a public electricity supply is desirable especially if chilling of carcases is being considered or on site water pumping is required.
1.5.1 Slaughter Floor
The slaughter floor layout is shown on Drawing 2. The designs assume procedures for slaughter of each species as follows:
The animal is led into the bleeding area where it is restrained by a tether through the floor ring prior to stunning (using a captive bolt pistol). After stunning the animal is shackled by one leg and hoisted, with a rope pulley block. The animal is then stuck and allowed to bleed in this position and the blood collected in a drum for disposal.
Once bleeding is complete the head can be removed and the animal lowered onto the cradle for dressing. The feet are then removed, the skin opened up along the breastbone and the hide partially flayed. Leg hooks are then attached and the carcase raised to a ‘half-hoist’ position on the spreader. Flaying can then be completed and the hide removed. The paunch can then be removed to the inspection buggy and the red offals (including lungs if treated as edible) placed on hooks or the inspection table for inspection.
After inspection the carcase can be split and quartered, the quarters being individually hung on the low rail.
Once the carcase has been partially flayed and half-hoisted a second animal can enter the bleeding area.
Pigs are first stunned in the stunning area then hoisted for sticking and bleeding and then transferred to the scald tank. After scalding for approximately five minutes at 60°C the carcase is removed to the scraping table. After scraping a gambrel can be inserted into the hind legs and the carcase transferred to the overhead rail for final scraping and evisceration. Once a pig is clear of the scraping table the next pig can be placed in the scalding tub.
Sheep and Goats
These would be slaughtered and dressed on the rail in the pig area in a similar manner to pigs. The scraping table is removed to one side during processing of sheep and goats.
Generally the lairage should be sized to hold the expected daily kill. This will allow stock to be held overnight before slaughter. In some special cases a greater capacity may be required although the holding of stock at the abattoir for an extended period before slaughter should not be permitted.
Lairage areas for each specific abattoir should therefore be assessed relative to expected throughput. Pen areas required for each species are as follows;
The lairage shown in the model has been sized to accommodate 4 cattle in two pens of 2 each and 28 pigs or sheep in four pens of 7 each. Alternatively up to 40 goats could be held in the small stock pens or a mix of the two species held. A single pen for isolating sick or suspect animals is also shown. Unloading facilities for trucks have not been shown as in many cases these will be unnecessary. If required these should be designed locally.
In localities where animals, particularly cattle, are normally tethered, a larger area without dividing fences may be preferred to allow tethering rather than penning of animals.
The chiller shown is a proprietary module with a holding capacity of approximately 300kg and a chilling capacity of 150kg/day. In this size range the use of a prefabricated unit has the advantage that complete assembly and testing before leaving the factory is possible. Also a factory built and tested unit will generally be the lowest in cost as skilled on site work is minimised.
1.5.4 Inedibles/Condemned Material
For a plant of the size described here the operation of a by-products plant would not be economic.
Two possible methods of disposal suitable for a plant of this capacity are:
A simple incinerator could be constructed from a used oil drum as described in VPH/83.56.1 In practice however such incinerators are difficult to operate and require substantial quantities of fuel to ensure adequate destruction of meat and offals. Incineration is therefore not recommended.
The preferred alternative, a disposal pit, is simple to use and once constructed costs nothing to operate. Most of the material placed in the pit will slowly decompose, and for an abattoir of the size described, such a pit will be usable for many years. A suitable pit is detailed in Drawing 12. Construction will however need to take into account ground conditions particularly the ground water level (the pit should not extend below the normal water table). In suitable ground conditions it may be possible to dispense with the lining to the lower portion of the pit. It is particularly important that rain water does not enter the pit hence the walls of the top section of the pit should be solid as shown in the drawing.
1.5.5 Ruminal Contents
Particularly in the case of cattle a considerable quantity of ruminal contents has to be disposed of. A compost stack provides a simple and low cost method of disposal as well as providing a useful end product. Dung from the pens, effluent screenings and other wastes may be conveniently disposed of in this way. The addition of waste vegetable material such as maize and cassava stalks, straw etc. will increase the yield of compost and ensure aeration of the stack. A full description of the operation of a compost stack is given in VPH 83.56.1
For the smallest plants a simple compost stack will be adequate, but for larger throughputs, and particularly when a significant number of cattle are to be slaughtered, a permanent compost bunker should be provided as described in VPH 83.56.
1/ Guidelines on Small Slaughterhouses and Meat Hygiene for Developing Countries W.H.O. 1984, page 98.
Blood is a valuable source of protein. However at this scale a by-products plant to produce blood meal could not be viable. Blood should not however be diverted into the effluent system since it will quickly clog up the screens and disposal trenches.
By using the following treatments blood can be incorporated into stockfeed. It must be stressed that even if the treated blood must be given away this is still preferable to disposal of blood on site. (In the event that blood cannot be disposed of as stockfood a separate blood sump, similar to the solids pit could be constructed adjacent to the slaughterboard. But only as a last resort).
Alternative methods of treatment are;
Where pigs and poultry are kept nearby, fresh blood can be directly incorporated into bran, cassava or other stock food. This represents the simplest and most efficient means of disposal. With this method it is essential that the resulting meal be fed out the same day as it has no keeping properties.
Lime Treated Blood
Where a somewhat longer life for the feed is required approximately 1 % of unslaked (burnt) lime can be added to the blood container and stirred in as the fresh blood is added. The hardened product will keep for up to one week. It should be used as described for fresh blood.
Where it is not possible to directly add fresh blood to pig or poultry feed, it may be mixed with bran or cassava as described under (a) and dried in the sun, on either a concrete floor, or matting. Drying will generally be complete in three days. (The drying area will need to be covered in the event of rain). During rainy periods it would be necessary to dry the mixture on corrugated iron trays placed over a copra dryer or similar fire. Because of the additional cost of drying this method is only recommended where the methods described above cannot be used. Since all the methods described above for blood disposal use readily available local materials, construction details have not been provided in this report.
1.5.7 Hides and Skins
Three alternatives exist for the disposal of hides and skins:
The quantity and quality of hides and skins will determine whether or not it is worth saving and marketing the hides and skins produced. Where there is only a small cattle and goat kill the costs of preparing hides for sale may well outweigh the returns. In these cases the hides should be disposed of by burial.
Each case will need to be assessed individually however as a general guide the export of less than 100 cattle or 500 goat skins per annum is unlikely to be economic.
For most abattoirs built to this design this means that exporting will only be economic if hides and skins can be marketed in conjunction with those from other abattoirs.
Other factors that would lead to the selection of burial include:
Whenever expected returns outweigh costs hides and skins should always be processed for sale. For a single abattoir drying is recommended. Salting should be considered only when production reaches the equivalent of 30 cattle hides per week. This would necessitate the combining of production from several abattoirs and is not discussed further here1.
1 Refer Mann ‘Processing and Utilization of Animal By Products’ FAO, Rome for further detail of salting methods.
For abattoirs of this size suspension drying is recommended. Suspension drying can be carried out using locally made equipment and needs no other materials. Where throughput permits a simple a roofed area should be provided for washing and fleshing hides prior to stretching on drying frames. Drying frames for cattle hides should be approximately 3 metres square and can be made of bamboo or small round timbers lashed together at the corners as shown on drawing 18.
For a plant of this size two options for effluent disposal are practical.
Generally subsurface irrigation is to be preferred although where soil conditions are suitable the use of soakage pits may be simpler.
The discharge of effluent into water courses or other existing bodies of water is not recommended as this will lead to pollution. Effective waste water treatment, at this scale prior to discharge into water courses is generally impractical and certainly will be more costly than the simple methods of disposal outlined above.
This system is shown on the drawings. Planting of banana palms or paw paw should be made along the trenches to utilize the moisture and nutrients contained in the effluent. Root crops such as taro and cassava should not be planted over the trenches. It is possible only to give general guidance as to trench lengths required. One twenty five metre long trench as shown should however prove adequate in most cases.
Provision for a second trench is shown on the layout. If desired the irrigation trenches could be constructed outside the boundary fence so that crop management becomes the responsibility of an adjoining landowner. Root crops should not be grown over the trenches.
Where soil conditions are suitable (i.e. free draining) soakage pits may be used in place of irrigation trenches. No details of construction are presented here. However the importance of adequately covering any soakage pit must be emphasised. It should also be realised that even if wastes are efficiently screened, soakage pits will block up with time. Provision should therefore be made to dig additional pits in the future as the rate of soakage declines.
No details for stormwater collection and disposal have been shown on the drawings. Provision will have to be made to dispose of rain water from roofs and paved areas. The most appropriate means of disposal can only be considered once a site has been selected. Local practise should be followed.
1.5.10 Water Supply
The importance of a supply of clean potable water cannot be over-emphasised. The plans presented assume connection to a town main or pumped well supply. Hot water for washing has been piped to a single point in the abattoir only. While this will require the use of buckets and brushes for cleaning equipment this system does conserve water. Also cleaning in this manner is more effective than using low pressure hot water hoses.
Roof gutters have not been detailed. In areas where a piped water supply is not available roof gutters should be included and water collected into a tank located as shown on Drawing 1. Where tank water only is used provision of an electric pump is most desirable.
While a wide range of alternative energy sources have been discussed in the literature only a limited range of alternative energy sources are likely to be of interest in most abattoir situations.
When considering using alternative energy sources it must be borne in mind that the primary purpose of the abattoir is to provide hygienic facilities for animal slaughter and dressing; the incorporation of alternative energy sources should not require a large degree of management input. For this reason only alternative energy sources with a proven history in the area should be considered for installation in the abattoir.
For this reason, and because of widely varying costs of energy from conventional sources, each abattoir site will require individual consideration.
With the availability on site of raw material in the form of animal wastes and the requirement for hot water for processing, the generation of biogas should be considered.
It is not possible to give hard and fast rules for considering installation of biogas plants however the following guidelines list those items for and against installation.
Relatively large throughput, relatively constant both over the week and annually, (over 5 large stock per day or equivalent).
Previous history of successful biogas plants in the locality.
Shortage of low cost solid fuel for the boiler.
High cost of alternative fuels.
High pig kill (pig excreta yields more gas than cattle or sheep).
Intermittent killing pattern, large kills one or two days a week.
Low cost fuel available.
No other biogas plants in the area.
1.6.2 Solar Heating
Simple solar water heating panels unfortunately, cannot produce water temperatures required for pig scalding (60-65°C) thus supplementary heating is required. Also in many regions solar heat may not be available for significant periods. Because of this investment costs are inevitably high for heating systems incorporating solar panels and are likely to render such systems uneconomic except where fuel costs are very high. In these circumstances it is a direct competitor with biogas.
Where pigs are not slaughtered solar panels could however be used to provide warm water for amenities and for washing in the abattoir.
1.6.3 Solar Lighting
Where electric power is not available and early morning slaughter practised the use of solar cells in conjunction with storage batteries and low voltage fluorescent lamps should be considered. Standard systems are now available from several suppliers and would be very effective under these conditions.