According to Dictionary.com, milk is "an opaque white or bluish-white liquid secreted by the mammary glands of female mammals, serving for the nourishment of their young."
Milk is a sterile product when secreted in the udder of a healthy cow (we’re talking about cow milk). It is loaded with nutrients, which makes it a fertile ground for microbial growth. Due to its susceptibility to microbial spoilage, there is need to adopt clean milk production principles to reduce chances of contamination.
Since more than 65% of all animal protein is directly linked to dairy products, it is important to ensure that consumers get only the best. To guarantee the best quality, there is need to consider the whole value chain. Clean milk production needs to start at the farm, before the farmer milks the product from the animal.
In this article, Olivia Solon suggests the possibility (and availability) of nondairy-derived milk and related products. The term milk has also been used to describe the substitutes used to produce non-dairy beverages that resemble the real product both in color and texture. Indeed, products such as soy-milk, rice-milk, coconut-milk, or even almond-milk have existed for years.
The availability of non-animal dairy substitutes solves the problems of methane gas production in dairy farms. Methane production is a major concern for the environment, as the animals produce lots of greenhouse gas that contributes to the greenhouse effect.
Again, the availability of dairy substitutes solves the ethical problems associated with dairy milk production. One can consume the dairy product without the guilt of knowing that a calf was sacrificed somewhere to enable milk production.
History of Milk
Humans learnt to domesticate animals from as early as about 9000 to 7000 BC. Cattle, goats, and sheep were among the first animals to be domesticated. People then learnt that they could exploit the animals for consumable products such as meat and milk.
Later on, the domesticated animals were used to produce other secondary resources such as hair, wool, skin, and also to provide labor in the farms.
Dairy products used as dressing for burns
Historians believe that domestication of animals originally began in Southwest Asia, from where the practice spread to other parts of the world. Some of the earliest Egyptian records show that the burn treatments consisted of using burn dressings of milk from lactating mothers (specifically mothers of male babies).
Dairy products were historically not a large part of the diet in many parts of the world over a long period. The reasoning for this could have been because the communities never kept animals as they relied on hunting and gathering, or they simply did not keep the dairy species.
Milk consumption became common in these regions comparatively recently, due to the European colonialism and political dominance over much of the world.
The increasing demand for dairy products
With the coming of the industrial revolution, urbanization sprung up and people started moving from the rural; areas to the urban centers. The rising populations in the urban centers created demand for food, and dairy products became very popular. In fact, in the Middle Ages, milk was referred to as the virtuous white liquor because alcoholic beverages were safer to consume than water.
The rising demand for dairy products resulted into increased production of the dairy products to meet the demand for the urban center dwellers. Some unscrupulous traders began to add water into the milk to meet the demands and increase their profits. This not only reduced the quality of the product, but also made it unsafe for human consumption.
Safety Issues Associated with Milk
The rising concerns for the quality and safety of dairy products necessitated standardization in the dairy industry. Consequently, a legislation in 1875 made it illegal to adulterate milk on any form.
Earlier on, Louis Pasteur had developed a method (pasteurization method) to kill pathogenic micro-organisms in food products to make them safe for human consumption. Packaging of properly pasteurized commercial grade milk to make the standard uniform and to reduce contamination of milk later followed.
Packaging assured consumers of quality and safety of the dairy products. These efforts paid off as consumption soon increased by over 90 percent.
Where does milk come from?
By convention, all female mammals should be able to produce milk. However, there are special cases in which some of them are unable to produce. Humans do not produce it for commercial purposes.
There are milk-banks where the expressed commodity is stored and given to infants whose mothers cannot produce milk. This blog is specifically concerned with dairy milk.
FAO documents cow milk as the largest contributor to the commercial dairy products market.
In the West, commercialization of dairy production is very common. The system allows production of large volumes of high-quality milk consistently to meet the high demands for the products. They have automated/semi-automated farms to reduce production costs and to maximize the economies of scale.
Their dairy cattle are pure breeds of high producers such as the Holstein. They have continually improved the cows for increased milk production. Holsteins consist about 90% of the dairy cows in the United States and 85% in Great Britain. Other high yielding dairy cows in the United States are Ayrshire, Jersey, Guernsey, Brown Swiss, and the Dairy Shorthorn.
Subsistence dairy production
In most developing countries, the dairy sector largely lies in the hands of the informal sector players. Subsistence farmers with one or two indigenous cows (producing <10 l/day) produce most of the milk.
The production is very low and is labor intensive. The animals walk long distances to the pastures and watering points. Tropical diseases are also a challenge for the farmers, limiting their capacity to produce more milk.
Luckily, the dairy sector has seen a very big boost in the recent past due to increasing demand for milk and interventions by non-governmental players. Farmers have realized the need to do dairy farming as a sustainable business.
Many farmers have adopted the high yielding exotic breeds that produce more hence increasing the farmer's income. There is ready market for the dairy products in most countries, making dairy farming a lucrative venture.
Other Milk Producers (apart from cattle)
Aside from cattle; buffaloes, goats, sheep, camels, donkeys, horses, reindeer and yaks also produce milk. In fact, people have consumed their products and/or used them for making other dairy products.
Goats, sheep, and buffaloes are relatively high producers globally after cows. Goats milk has a close resemblance to human milk. It can be a better substitute for human milk.
Features of clean milk
- Free from debris and sediments
- Free from off-flavours
- Low in bacterial numbers
- Free of antibiotics and chemical residues
- Should have normal composition and acidity
As we have noted, you can only consider milk to be clean if it comes from a healthy cow. Therefore, every farmer must ensure that the animal is in proper shape health wise and provide clean feeds and water, in the right quantities and at the right time.
At the farm, the housing must be right to avoid introducing contaminants into the products. The milking equipment must be clean and the milkers must be in perfect health to avoid transmitting zoonotic diseases that may compromise quality of the product and safety of the consumers.
Understanding the concept is key to implementation of the principles of clean milk production.
Clean milk production is not only important for public health concerns but also for profit generation at the farm.
Necessity of clean milk production principles:
- Consumers will reject dirty milk at the market. Since you had spent money in feeds, medication and labor, there’s no way you will get your money back. Consumers may even learn to boycott your products if the quality issues persist.
- Dirty milk is extremely difficult to handle because it goes bad pretty fast. You will most probably throw it away due to its short shelf life.
- Dirty milk is a rich medium for the transmission of food borne and zoonotic diseases. Cross contamination with such conditions such as mastitis will reduce productivity at the farm.
- Clean milk helps in controlling the spread of infectious diseases like Tuberculosis and Diphtheria etc. You and I know that a sick nation cannot grow.
- The government will lose revenue from the dairy sub-sector. Considering that the dairy sub-sector contributes 30 percent of the national economy, which contributes 10 percent of the Gross Domestic Product (GDP), this will be a substantial loss.
- Producing clean milk will make you a more satisfied farmer because you know that your consumers are getting only the best products.
Principles of clean milk production
Before we delve into the actual principles, we should understand the kinds and sources of contaminants we’re dealing with. We can classify milk contamination into two broad categories: internal and external factors.
- General health of the cow e.g. presence of mastitis or tuberculosis
- The first few streams of milk may have a higher bacterial load as a result of bacteria that enter the udder through the teats.
- Cow/animal’s body – especially dirt and dung from hind quarters and tail
- Milker – hygiene and habits
- Milking and storage utensils
- Method of milking
- Feed and Water
- Milking Environment
Here is a comprehensive list of the sources of contamination in milk. Clean milk production requires a holistic approach that will address animal health, dairy animal management, nutrition, hygiene, and ancillary equipment.
You should consider the following while implementing clean milk production systems at the farm.
- The dairy animal management activities include feeding/nutrition, housing and health
- Hygiene management entails the cleanliness of the animal, the handlers, the housing, and the milking equipment
- Health of the milker and milking practices used at the farm level
- Check the condition of the milk handling equipment during storage and transport
There are measures at every stage that you should implement to ensure that you produce the best quality milk. You will be able to identify all the critical control points where you will put preventive measures to avoid contamination.
Managing animals at the farm for clean milk production
When you have a healthy cow, it secrets sterile milk in the udder. Contamination begins almost immediately when the milk leaves the udder through the teats as the contaminants get into the milk. Contamination, especially bacterial type, is inevitable. However, there is an acceptable limit for the contamination; a threshold within which the product is still considered safe.
The bacteria that gains entry into the milk will lead to deterioration in quality of the product and affect its suitability for processing into the finished products. For this reason, it is recommended that you pasteurize the milk to kill the spoilage bacteria. Pasteurization does not kill the spores, which can still germinate and cause spoilage in the dairy product.
Moreover, some bacteria will produce toxins, which are very stable and does not degrade during pasteurization. Any milk that has poison before pasteurization will still cause intoxication of the consumers.
It is important to ensure that the animals get proper nutrition and housing. The housing should shield the animals from the extreme weather.
a) Feeding the cows for clean milk production
Feeding is a central activity in dairy animal management. When designing the feeding schedule, ensure that the animals get adequate rest between feeding and milking (at least one hour). The animal feed should be clean and nutritionally sound with all the required nutrients in the right proportions and free from contamination.
During milking, keep the animal busy by providing concentrates.
If you are making your own feeds, ensure you have a balanced diet with all the required nutrients. Avoid products that have traces of contaminants such as pesticides, radionuclides, persistent pollutants, and toxins. Assess all feed additives and drugs you use to treat the cows to ensure they do not cause contamination. Follow manufacturer’s instruction and consult your vet.
Failure to assess all these items will lead to contamination of the dairy products, which can be catastrophic.
In any case, always observe the following points when managing a dairy animal for clean milk production:
- Ensure the feeds and fodder contain no pesticides, insecticides, fungicides, herbicides, aflatoxins, and metals.
- Always store your animal feeds with the minimum allowable moisture content.
- Handle farm chemicals with a lot of care because they can easily find their way into the milk.
- Avoid giving the animal silage and wet crop residues during milking to avoid imparting any off-flavor to the milk.
- Ensure the animal gets adequate supply of key minerals and vitamins.
b) Proper housing for clean milk production
The cow shed is a major source of contamination at the farm due to the presence of dust, mud, dung, and urine. The milking crush/stand needs to be clean because it is a primal source of contamination.
A properly designed cow shed will protect the cow from parasites and pathogens that come through contact. It keeps the unwanted people and animals out of reach and protects the cows from extreme weather.
Design the cow house to facilitate easy cleaning so that you can remove the dung and mud regularly. Water and urine should drain easily. When you keep the shed clean, well aerated and lit, even the flies will reduce since they love dirty places.
Clean the floors regularly and apply disinfectant. You can use one percent bleaching powder solution to prepare the disinfectant solution. Supply adequate amounts of clean potable water, which the cows will drink. You will also use the same source of clean water for cleaning the cow shed and the cows themselves, especially the flanks during milking.
Here are the handy tips for managing the cow shed:
- The cow shed should be well constructed to ward off extreme weather, and well-drained to avoid stagnation of water. Stagnation encourages breeding of pathogens, which cause contamination. Always keep the shed clean and dry.
- Remove all the remains of fodder and feeds. Clean the feeding and watering troughs before every feeding session. Design the cow shed to facilitate removal of wastes. Dispose the manure in a pit or biogas plant.
- Overlay the windows with a wire mesh and a net to keep off flies.
- Arrange the farm in a manner to facilitate easy access of the feed store. Avoid putting up chicken house within the premise of your dairy project, it will contaminate the milk.
- Ensure each animal has enough space for feeding, sleeping and exercising. Provide sleeping mattresses for the cows to avoid injuries from the hard floors. You can fill up gunny bags with sand or sawdust for the sleeping mattresses if you cannot afford the rubber mats for the moment.
c) Animal health management for clean milk production
As you are already aware now, the primary source of clean milk is a healthy animal. There is no way around it; you must just get it right. You should know how to detect the diseases and how to manage each. The best thing that will save you a lot of money is learning to prevent the diseases from ravaging your herd.
Conditions such as mastitis are very difficult to control once they enter your herd. This is because most cows that have the condition are still in the sub clinical stage of the disease. Learn to adopt vaccination and hygiene management for preventable diseases.
You can implement the following measures to promote clean milk production at the farm:
- Examine your animals regularly to ensure your animals are free from contagious diseases such as brucellosis, mastitis, TB, etc
- Identify and separate sick animals from the healthy ones. Treat them separately to avoid spreading the disease to the healthy animals.
- The animals suffering from contagious disease must be kept separate from healthy herd. Sanitary precaution to prevent and control the disease should be adopted.
- Avoid mixing milk from cows with mastitis with that from healthy cows. Always milk the sick cows last and use their milk to feed the calves.
- Vaccinate the animals as regularly as is needful for such diseases as foot and mouth (FMD) and Anthrax. Consult your vet for a personalized advice.
- When cleaning the udders, use disposable towels to dry up the udders. Do not share the towel among many cows.
- The milker should be in perfect health to avoid contaminating the dairy products.
Managing Somatic Cell Counts (SSC) for clean milk production purposes
The Somatic Cell Count (SCC) is a very reliable indicator of milk quality. High SCC is due to the leukocytes (white blood cells) – which are released into the animal’s system as an immune response to an infection.
The most common trigger for high SCC is mastitis infection in cows, which alters the milk composition and reduces the milk yield. If untreated, mastitis can affect the lifetime productivity of a dairy animal. Mastitis milk has a characteristic low lactose, casein, butter fat and calcium but high immunoglobulins, somatic cells, pathogenic bacteria and sodium.
Injuries to the udder will lead to increased SCC since the animal’s immune system produces the leukocytes to intervene. To a great extent, the SCC count will indicate the level of hygiene maintained at the farm. Check the milk after every two weeks for the SCC index to ensure that your herd remains within the prescribed boundaries.
Essentially, SCC is the number of cells (leukocytes) per ml of milk. The boundaries are described as follows:
- SCC of 100,000 or less: – ‘uninfected’/’normal’ cow. Such a cow has no significant losses due to subclinical mastitis.
- SCC of 200,000: – confirmed infection with mastitis. You are highly likely to find infection in at least a single quarter. There is a slight change in milk.
- SCC of 300,000 or greater: – significant infection with visible change in milk observed. Anything over 400,000 is unfit for consumption.
Manage hygiene at the farm and remove wastes such as dung and leftover feeds regularly. This will help you avoid breeding of pathogens that cause infections.
When one animal is infected, separate it from the rest of the herd and treat. Do not mix its milk with the rest of the bulk. Neither should you sell nor consume such milk.
Keep the sick animals clean and comfortable to facilitate rapid recovery and to avoid further spread of the infection.
Managing hygiene of milking equipment and utensils for clean milk production
There are very many equipment and utensils for handling milk at the farm. The milking machines, the piping system, bulking tanks, strainers, teat cups, milk churns and pails, etc., are all critical points of milk contamination at the farm.
Regular cleaning is necessary to avoid accumulation of dirt, which encourages bacterial growth. You must ensure that you conduct thorough cleaning with detergents at the right concentrations and temperatures to eliminate all pathogens.
Use CIP cleaning for the stationery equipment and pipe work. Ensure the detergent concentrations are right and provide enough temperature/contact time for effective cleaning.
Sanitize all surfaces that come into contact with milk after cleaning.
- Clean and sanitize all the milking/milk handling vessels before and after every milking session. Usually, after you have effectively cleaned the equipment after milking, you will only need to sanitize it before milking. Sanitize the equipment at least 20 minutes before you start milking. Do not forget to pour out the sanitizer before adding milk into the container.
- Use detergents that are easy to rinse off the equipment. Soap is discouraged because it is difficult to completely rinse. You can use sodium hydroxide as a sanitizer.
- After cleaning, invert the equipment/utensils to dry up; that way, few bacteria will settle in it.
Managing hygiene for clean milk production
Hygiene is key to determining whether you produce clean milk or not. It transcends across all the stages we have discussed and is a central key in each. Every activity you do at the farm should be geared towards achieving high standards of hygiene.
There are critical points of contamination such as cow teats. Most bacteria take advantage of this window and fall into the milk during milking. The cow may also introduce the pathogens into the milk by dipping its tail or foot into the milk vessel during hand milking.
Dirty workers may also introduce pathogens into the milk. If the workers smoke, the milk will have a tobacco odor, which is not desirable. Similarly, workers should not wear perfumes at the odor will pass to the milk.
Ensuring adherence to high standards of hygiene will help you reduce contamination and produce clean safe milk.
The following are some measures you can implement to improve hygiene at the farm:
- Do not sweep or clean the floors during milking as that may introduce pathogens into the milk.
- The milkers should be in perfect health and free from communicable diseases. They should use head/beard gear to cover their hair or trim it to avoid contamination. Their nails MUST be short and they should wear protective gear while working. They should not smoke near the milking parlor and they should not spit or blow their noses while milking.
- The milker must clean his hands with soap and rinse adequately before milking. He should dry his hands with a disposable towel. I am advocating for disposable towel because they eliminate chances of re-contamination. Hand driers are dangerous because bacteria love warm places.
- Clean the udders before you start milking. Use potable water and a clean towel. Soap is discouraged because it may get into the milk.
- Secure the animal in the crush and use a kick stopper to prevent the animal from spilling the milk or dipping its leg into the milking can. If you are using machine to milk, secure the teats properly and avoid letting air into the system.
- Every milking session should last an average of seven (7) minutes. Desist from the practice of dipping your fingers into the milk to wet the teats. In fact, avoid wet milking if you want to guarantee your milk hygiene.
- Dip the teats into a bacteriocide after milking to avoid bacterial infection. Give the animal some feed or ensure it remains standing for the next several minute until the teat canals close. If they sleep in dirty places immediately after milking, bacteria will have an easy access into the udder.
- After milking, strain the milk through a clean strainer/muslin cloth to remove debris and other foreign matter. A centrifugal separator removes the soil very efficiently. Clean the strainers as regularly as possible. Clean the muslin cloth using detergents and dry it.
- Immediately after milking, weigh the milk and cool to avoid multiplication of bacteria. The milk storage room should not house other chemicals or grains. Deliver the milk to the dairy in the morning or evening to avoid heat of the day. Use a covered vehicle/means of transport to avoid direct sunlight.
- Use seamless aluminium or stainless-steel cans, as they are easy to clean and do not harbor pathogens. Seams create a fertile ground for bacterial multiplication.
- Use clean and potable water at the farm because it is an easy route for contamination since you will be using a lot of it.
- Draw samples using clean equipment and follow all the Quality Assurance guidelines for sampling.
Milk cooling for clean milk production
Bacteria replicates rapidly under warm temperatures. You must chill the milk to arrest bacterial activity and avoid spillage if you are not going to process the milk immediately.
Chilling will enhance the quality of milk before it reaches the dairy plant. You can achieve cooling through various means. The most obvious one is refrigeration. However, not every farmer has refrigeration facilities. In such cases, you can improvise a home-made charcoal cooler or use chilled water.
When you use the chilled water for cooling, immerse the milk churn into a larger container with water. Ensure that the level of water in the outer container is above the level of milk in the churn for an effective cooling. Change the water when its temperatures get warm (use your skin to feel).
Ensure you do not fully cover the top of the milk can to avoid off flavors from accumulating.
If you are selling to the dairy and they pick the milk from a designated place, ensure that the place has a shade to avoid direct sunlight.
After milking, bacterial contamination is the major cause of deterioration in quality. The sooner you arrest it, the better for you.
Here’s the recap of the cooling activities you can implement:
- Cool the milk to less than 5°C immediately after milking. Most bacteria will not multiply at this temperature. Be careful to ensure you cool the milk immediately after milking because if you wait, it will develop acidity, which you cannot remove by cooling.
- Deliver the milk to the dairy within two hours after milking if you do not have the cooling facilities.