1. THE MANAGEMENT OF THE DAIRY
There are very specific requirements for managing a successful dairy and there is a list of requirements. These include:
- Dairy equipment;
- Dairy machinery;
- Dairy utensils;
- Dairy hygiene;
- Labour Management;
- Dairy buildings;
- Water supply;
- Power supply;
- Food storage facilities;
- Food mixing facilities;
- Storage of silage and;
The list becomes endless, but you will begin to realise that the managerial aspects of dairying are extremely wide and, depending on the size of the unit, the job could be too much for one man. If this is the case, management aspects would have to be shared by two or more men.
2. REQUIREMENTS FOR FARM DAIRIES
Although there are very many designs for dairy buildings and dairy equipment, and new ideas are continually being introduced, there are certain basic requirements common to all. It is important that the buildings and equipment should be designed to meet individual requirements. The systems used should provide maximum efficiency. Also, the requirements of dairy legislation must be met.
This simple guide has been prepared to assist producers in planning their dairying projects. It is intended only to convey the basic principles. As cows have to be milked at least twice a day for 365 days of the year, the importance of careful planning cannot be over-emphasised and it is strongly advised that before proceeding with any building, assistance should be obtained from a dairy consultant.
SITING OF DAIRY PREMISES
Dairy buildings are probably the most frequently used buildings on the farm, and very careful consideration should be given to the siting of these premises. It is important that they should be easily accessible both by road for the daily despatch of the milk, and for the cows which come to them at least twice daily. Other important points to be taken into account are that the premises should be:
- Within reasonable distance of the homestead, but not less than 100 metres to any residential quarters;
- Situated on well-drained ground, preferably higher than the surrounding area to facilitate drainage;
- Be provided with a good piped water supply that has an adequate supply of clean, safe water readily available;
- Be conveniently placed for the supply of electricity;
- Be situated so as to fit into the general farm layout with easy access to grazing and feeding pens;
- Be sited on the windward (up wind) side of roads and other dusty places in order to keep dust to a minimum in the dairy;
- Be at least 100m away from pigsties and from any accumulation of manure, feeding kraals, compost heaps etc. and;
- Be sited so that the dairy and wash-room can be on the windward side of the milking shed. The cows will thus be protected as far as possible from the elements.
THE MILKING SHED
There are many satisfactory designs for milking sheds and milking parlours, and very careful consideration should be given to the routine to be followed, as well as the equipment to be used before a design is finally decided upon. It is strongly advised that the layout and construction should be discussed with a dairy consultant, and, if a milking machine is to be installed, the agent of the firm responsible for the installation should be consulted or present.
The following points provide a general guide to requirements for a milking shed and are applicable to parlours as far as construction materials are concerned:
- A conventional milking shed should be large enough to accommodate all milking cows at one time. Such a shed can be used successfully if it is large enough to accommodate all the milking cows in not more than in 3 relays. The size and through-put of a parlour depends on the design and the time available for milking;
- The floor must be of concrete. Concrete should be laid on a good hard core to a depth of about 10cm, and if constructed properly should last the life of the building. Efforts to economise on concrete work frequently lead to trouble and prove to be a false economy as a poor floor can never be effectively repaired. The floor should have a fall of 5cm from the manger to the manure channel and the whole milking shed floor must slope towards the draining point. A fall of about 25cm in 10 meters is suitable. Manure channels should be wide and shallow (a depth of 10cm is generally ample) and should have straight sides in order to minimize the danger of cows slipping;
- The floor should be smooth enough to allow easy clearing, but must not be slippery, otherwise animals may fall and injure themselves;
- Good ventilation and lighting is very important;
- It is advisable to provide feeding passages in front of the cows and these should be one meter wide;
- The manger should be 70cm wide from front to back in order to allow the cow sufficient room to lift its head into a comfortable position without stepping back into the manure channel. It is advisable that the manger should be about 70cm high on the feeding passage side and 25cm high at the standing;
- It should be so built that the lowest point is about 2 ½cm above the level of the standing and 25cm from the inside of the wall at the standing. An open type of manger is most suitable as individual mangers are difficult to clean;
- Stall divisions should preferably be of metal piping, allowing a width of 1 meter per cow. The divisions should be two-thirds of the length of the standing;
- Cow ties, yokes, or side or centre chains may be used for tying the cows. Whatever type of tie is used, a quick release device should be incorporated;
- In a double range shed, the cows should face away from each other, and the central walk and dunging passage should be at least 2 metres wide. If cows face each other there must be a feeding passage of at least 1 ½ meters wide;
- The roof should be of corrugated iron or similar material and may be of pitched or lean-to design. It must be high enough to provide ample head room and a minimum of 2.75 meters in height and;
- Walls should be of brick or similar material, and should
be cement plastered on the inside to a height of at least 1.52 meters.
THE DAIRY ROOM AND WASH-UP ROOM
These should be situated in a convenient position from the milking shed and for supervision of the work going on.
The following is a general guide to construction:
- Walls should be of brick or similar material and all internal walls must be smoothly plastered. The average height should be at least 2.74 meters;
- Floors must be constructed of impervious material (concrete) and should have a ‘two-way’ slope to facilitate drainage;
- Adequate light and ventilation are essential;
- A suitable ceiling is advisable in the dairy room and is essential for certain types of roof construction and materials;
- Doorways should be wide enough to allow equipment to be moved into the rooms;
- The rooms must be fly-proof and rodent-proof and;
- The size of the rooms depends on the amount of milk to be handled, but the dairy and wash- up should not be less than 4 meters x 4 meters.
MILKERS WASH ROOM AND LAVATORY
The Government Regulations require that adequate washing and sanitary facilities be provided.
A room fitted with a shower should be provided as a washing and changing room for dairy staff. If water-borne sanitation is provided, the lavatory may be part of the dairy building. Otherwise a properly constructed latrine situated at least 30 meters away from the dairy premises must be provided.
A clean, safe water supply is essential and if there is any doubt about the purity of the water, it must be suitably treated. Plentiful quantities of water are important for dairying purposes.
Disposal of effluent must be carried out in an approved manner. This may be:
- A sump which must be emptied daily;
- A French drain. A solids trap is essential to prevent the French drain from becoming blocked and useless and;
- A cement-lined drain leading to the compost heaps or an irrigation system.
The main requirements are:
- Suitable equipment for providing adequate supplies of hot and cold water;
- Three rust-proof metal wash troughs, semi-circular in sections and approximately 0.8 x 1.3 meters;
- All joints should be smooth and sealed. Concrete wash troughs are not acceptable and;
- If milk is to be kept for any length of time, or delivered once a day, suitable mechanical form of refrigeration is essential. The most popular and effective way of cooling on a small farm is the churn-immersion system. These may be used in conjunction with in-churn or surface coolers, using chilled water from the immersion tank.
All dairies must be approved and registered before milk may be sold.
3. COOLING OF MILK
Why does milk go sour? There are many answers, few of which successfully provide a full explanation of the phenomenon.
It is apparent to most people that fresh milk has a slightly sweet flavour, which is due to the milk sugar lactose. As bacteria present in milk grow and reproduce, they attack the lactose, breaking it down into lactic acid. It is this lactic acid, as mentioned before, which is responsible for souring. Thus the rate of souring is proportional to the number of bacteria. That is, the more bacteria in the milk, the sooner it will go sour at room temperature.
Therefore, it is imperative that the number of bacteria in milk is kept to a minimum and that those
which are present are prevented from growing and developing. This is achieved by reducing their activity. This is accomplished by cooling down the milk to below 37°C, which is body temperature.
An interesting experiment was carried out in which a sample of whole milk was taken, and cooled down immediately. Then the milk was slowly warmed to 37°C over a 24 hour period. Using special techniques, samples were taken from the original sample and the number of bacteria counted, and the results were as follows:
It can clearly be seen what the effect of cooling has on the growth and development of the bacteria. Since the bacteria are solely responsible for the spoilage of the milk, it is important that their numbers are controlled by cooling the milk. Notice that between 0°C and 6°C there was little increase in the number of bacteria over a 24 hour period. However, at the higher temperatures, the rate of growth was more rapid, as shown by the increase in the number of bacteria per millilitre of milk.
Not only is it important to cool milk and keep it cool, but it should be cooled as quickly as possible after extracting it from the udder of the cow. If conditions of management are hygienic, it is still possible for milk to become contaminated by bacteria because they are found everywhere all the time.
If the milk is allowed to stand, the bacteria will grow at an incredibly rapid rate as can be seen from these results:
From this it can be seen that there is an extremely rapid growth of bacteria and that it should be controlled. The cheapest way to control it is to cool the milk as rapidly as possible. You can understand why you cannot add chemicals to kill the bacteria. It might kill the human beings who will consume the milk. Therefore, you can understand the importance of cooling milk and keeping it cool until it is consumed. Then it will be a highly nutritious food.
You will remember that, when we were discussing milk, you were told that milk is an extremely good medium for bacterial growth and development because of its high nutritional value. What are the microscopic animals called bacteria? It is probably easy to define them by saying that they are organisms which are found everywhere and have the ability to spoil foods and cause diseases. Since they are living organisms, they require food for growth and energy. These nutrients are taken in through the cell wall, and before doing so, they must be broken down. Bacteria produce enzymes which break down foods into:
- Fats and;
Bacteria require moisture and warmth for their successful growth and development.
Facts about Bacteria:
- They cannot grow in concentrated solutions of salt and sugar, consequently these substances are used to preserve foods;
- They cannot grow in a dehydrated medium, i.e. one which has been dried. Thus dehydrated foods have a longer shelf life than normal foods. Powdered Milk, dried meat and dried fruit are examples;
- Bacteria can grow at different temperatures. Very high temperatures tend to kill bacteria. Very low temperatures, although they do not kill the bacteria, slow down their activity;
- Bacteria may also be killed by chemicals but this form of control is extremely expensive. Some chemicals, in fact, can kill humans. Therefore, we do not normally recommend the use of chemicals for controlling the growth of bacteria in milk and;
There are different types of bacteria. These can be divided into a series of groups according to their growth habits and spoilage mechanism. For example, there are the:
- Acid-forming bacteria;
- Gas-forming bacteria and;
- Peptonising bacteria – bacteria which destroy proteins.
From this it can be seen that milk, which is a highly nutritious food, is susceptible to contamination by bacteria. One simple way to preserve milk is to cool it. Although this method does not preserve the milk indefinitely, it will preserve it for a short time.