IMPORTANCE OF MILK HYGIENE IN VETERINARY PUBLIC HEALTH PERSPECTIVE

IMPORTANCE OF MILK HYGIENE IN VETERINARY PUBLIC HEALTH PERSPECTIVE

Bidyut Prava Mishra

Assistant Professor

Department of Livestock Products Technology, C.V.Sc & A.H., OUAT, Bhubaneswar-751003, Odisha

INTRODUCTION

Milk is highly nutritious and rich in proteins with high biological value, essential fatty acids, vitamins and minerals and plays an integral part of human nutrition. It occupies a very special position in vegetarian people’s daily diet. Human milk can be substituted by the cow milk for the nourishment of infants and young growing children. Starting from new born baby to the immunocompromised old aged people, milk can be easily metabolized and utilised inside the body. Milk obtained from a healthy animal always free from any contamination and may not be responsible for transmission of any disease causing agents to human body through consumption of milk. But, sometimes milk may act as a vehicle for transmission of many zoonotic diseases, when milk is obtained from any infected animal. In some other instances such as, contaminated milking environment, infected milk handlers, uncleaned milking utensils or exterior surface of the dirty animals may be responsible for the contamination of fresh milk during milking or during processing of raw milk in the milking barn. Due to lack of personal hygiene of the milk handlers during milking, many disease causing agents get transmitted to milk and from milk to humans through consumption of those contaminated milk. So, to reduce or to prevent the transmission of such disease causing agents to human being through milk, strict sanitary and hygienic practices should be followed at each step of milk collection, chilling, processing, storage and distribution.

Milk may be defined as wholesome, fresh, clear lacteal secretion obtained by the complete milking of one or more apparently healthy udders, excluding that obtained within 15 days before and 5 days after calving or such periods as may be necessary to render the milk colostrum free, and containing the minimum prescribed percentage of milk fat and milk solids-not-fat. According to Prevention of Food Adulteration Act (PFA, 1955) milk may be defined as the normal mammary secretion derived from complete milking of healthy milch animal without either addition there to or extraction there from. It shall be free from colostrum.

Hygiene

It was derived from “hygeia” which means goddess of health, is a Greek word. It is the science of health and embraces all factors which contribute to the healthful living of an individual.

Milk hygiene

The science concerned with production of clean wholesome milk which is free from bacteria or other disease causing organisms which may produce disease among consumers or cause the milk to spoil too quickly and to preserve in fresh state until it is taken from farm to consumer.

Public health

It is the art and science of preventing diseases, prolonging life and promoting human health and efficiency through organized community effort such as sanitation, vaccination, diseases treatment etc. Public health is nothing but human herd medicine.

Veterinary public health

Veterinary public health is a component of public health activities devoted to the application of professional veterinary skills, knowledge and resources to the protection and improvement of human health. (WHO/FAO1975). The contribution to the complete physical, mental and social well-being of humans through an understanding and application of veterinary medical sciences (WHO/FAO, 1999).

The field of milk hygiene has 4 important components to preserve and improve human health.

• Preventing the transmission of diseases from animal to man.
• Preventing the communicable diseases of human to be transmitted through contaminated milk.
• Preventing diseases and physical defects that may arise from malnutrition.
• Improving the nutritional status of man, in general, infants, children and mothers in particular.

IMPORTANCE OF MILK HYGIENE

• Milk is a vital food for human and it is very close with life and culture of human beings. It is consumed by human of all ages including very old people, infants and lactating mothers.
• It is also intimately related to religious and socio culture of people. Like in Odisha curd is used as panchamruta in Sankranti, makhan related to lord Krishna and rasogola was invented in Odisha.
• So the quality of such an important food item is very important which safe guard the interest of both consumers and milk producers.
• By improving the milk quality, the consumers get nutritional value. The producers of milk are also benefited by producing quality milk by which they can get better price and can expand their business. Milk price is also dependent on the quality of raw milk.

SOURCES OF CONTAMINATION

1. Milk is secreted from mammary gland in almost sterile condition but gets infected during milking, cooling and storage.
2. Milk is an excellent medium for bacteria, yeasts and moulds because.

• It furnishes all nutrient requirements.
• It contains adequate moisture (85-90%).
• It has a favorable pH (6.5-6.7) most of organisms grow in a pH rang of 5.6-5.7.

3. The multiplication pH pathogenic organisms depend on storage temperature and presence of other competitive bacteria.
4. Several pathogenic bacteria may not multiply freely in milk but diseases producing ability of bacteria depends on initial load of bacteria, storage time, temperature, processing method.
5. Milk gets contaminated once it leaves alveoli and reaches teat canal. When milk is exposed to the teat, it gets contaminated from environment.
6. The key source of contaminations is

• Animal itself.
• External environment of a cow.

ANIMAL ITSELF

Normal microflora of udder- mostly Micrococci is predominant. followed by Micrococci, Streptococci, Bacillus, Coliformis, Pseudomonas, Proteosus type organisms.

Disease condition of cow-In mastitis, clinically affected cow shed 10 million of bacterial cell itself.

Animal suffering from bovine or human diseases may excreta the causative agent in milk lake My bacterium bovis, Brucella abortus, Coxiella brunette, Clostridia, Leptospira etc.

Body coat of cow-Common organisms like Bacillus and Coliforms coming from soil, dung, bedding material present on body coat contaminate milk.

External surface of udder and teat-Staphylococcus aureus mainly present on the surface of udder.

EXTERNAL ENVIRONMENT OF COW

1. Cow shade and milk barn -Materials like soil, manure, bedding material feed residues are physical contaminants which are sources of spores of Clostridia and
2. Rhodents, flies and insects are also source of physical contamination in the shade.
3. Water-It is an important source of contamination of various faecal bacteria like Coliforms, Pseudomonas, faecalstreptococci, Clostridia, spores of Bacillus, Corynbacterium, Salmonella, Shigella and Vibrio cholera.
4. Milker and milking practices – Common organisms like Coliforms and Staphylococci pass from uncleaned person handling the milk.
5. Milking utensils -These contribute largest portion of organism in milk.
6. Micrococci, Gram (+) spore forming and non-spore forming bacteria, Gram (-) rods are present on surface of utensils.
7. Storage and transport condition of milk –Appropriate cold chain facility should be maintained during transportation and storage of milk. Pseudomonas, Streptococcus, Enterobacter and E. coli are pre dominantly observed during faulty storage and transportation condition.
8. Machine milking – It is a potential source of thermoduric bacteria.
9. Processing plants- Commonly found organisms in air in dairy environment are yeast, mould, Micrococci, Coliforms, Corynbacterium, Streptomyces, spore or non-spore forming rods, Staphylococcus. In Indian condition, Micrococci is predominant organism.

MILK -BORNE ZOONOTIC DISEASES

Many fatal zoonotic diseases (brucellosis, tuberculosis, Q-fever, toxoplasmosis etc) as well as infectious diseases get transmitted to human beings through consumption of unpasteurized milk. To maintain food safety, milk must be obtained from disease free animals and also strict sanitary and hygienic practices should be adhered during each step of the production chain of milk and milk products. Animals may excrete a huge amount of disease causing agents during the incubation period only when no clinical signs of disease will be observed by the animal. So, on a routine basis, milk samples should be collected from the milking animals to detect the presence of any infection in the animal body. Some pathogens in animal body may remain as a normal intestinal flora and may not be responsible for development of any disease condition in them but when that flora contaminate the milk, they may get transmitted to human being through faeco-oral route and causes severe form of diseases. e.g. E. coli 0157:H7, tuberculosis, brucellosis etc.  E. coli 0157:H7 remain as a normal intestinal flora in animals but when enters into human body through consumption of milk contaminated with faecal material of animals may cause bloody diarrhea, renal failure and even death in case of high doses of intake. Also tuberculosis and brucellosis infected animals used to shed organisms in the milk during the incubation period of the disease in animals. The diseases such as brucellosis, tuberculosis, anthrax, leptospirosis, cow pox, pseudo cow pox, staphylococcus aureus, Q-fever, E. coli infection, FMD virus, salmonellosis, actinomycosis, listeriosis, hepatitis, campylobacteriosis etc. get transmitted from infected animals to milk and from milk to human being upon consumption. Some diseases such as staphylococcal infections, streptococcal infections and diphtheria etc., also get transmitted from infected milk handlers to animals and from animals to milk and from that contaminated milk to human being upon exposure through consumption of those contaminated milk. In another category, some diseases such as typhoid, paratyphoid, cholera, enterovirus infections, infectious hepatitis, adenovirus infection, shigellosis etc., may get transmitted from infected milk handlers to milk directly in the milking barn and from milk to human being through consumption of those contaminated milk. Besides contamination of milk through pathogens, it also may get contaminated by some physical contaminants such as addition of dung, bedding materials, animal hairs, dust of the milking barn, dusty animal feed materials etc. in the milking premises. Uncleaned and non-sanitized milking equipment, milking containers, milking pails and other equipment may also contribute to the addition of disease causing agents into the milk. Some chemical compounds that are used as feed and water additives such as insectides, fungicides may find their way into milk and contaminate it. Use of internal and external parasitic drugs, antibiotics, growth hormones etc., during animal growth and production system also provoke the excretion of these residues in milk and as a source of contaminant to the human beings. Some contaminants may migrate from the processing equipment and packaging materials into milk and milk products and contaminate the milk and dairy products.

STEPS FOR HYGIENIC MILK PRODUCTION

Animals should get vaccination regularly against common infectious diseases which are expected to pass through milk to human being. At every 6 months’ interval, health status of the milk handlers should be checked and should get vaccination annually against some common diseases which can get transmitted from them to milk as well as animal. During any disease condition they should not be allowed to work inside the milking premises. They should be provided with adequate training regarding how to maintain personal hygiene and sanitary practices during working inside the milking plant and processing unit. Animals having contagious diseases should be removed from the production chain. Milk handlers should use gloves, face mask, head gears and aprons and clean clothes while handling milk and milk products to avoid contamination of product from their side either through sneezing, coughing or fall of hair or dandruff etc. into milk. The milking barn should be provided with adequate ventilation facilities and it should be kept neat and cleaned to avoid air contamination to milk. Adequate cold chain facilities should be provided during storage and transportation of milk and milk products. Cleaned and properly sanitized containers should be used for storage and distribution of milk. Proper processing techniques should be followed to avoid contamination of processed dairy products.

CONCLUSION

Hence to reduce the chances of transmission of zoonotic diseases to human being through consumption of milk and milk products, hygienic measures should be followed starting from the point of production to till consumption. Prevention and control strategies should be strictly followed at each and every stage of production process to ensure quality of milk and milk products. Dairy farmers should get appropriate trainings through state government line departmental officers regarding the importance of hygienic practices during milk handling for curtailing the occurrence of milk borne diseases in human population. The dairy farmers at the grass route level also should get aware about the sources of contamination of milk at their farm and also various steps to prevent those contaminations at their level in the milk through various capacity building trainings for clean milk production. Minimum withdrawal period for various veterinary drug residues should be followed by dairy farmers to reduce their level in the milk.  So, by adopting milk hygienic practices at each and every step of milk handling and processing will definitely prevent and or reduce the chances of occurrence of milk borne diseases in human society.

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