MARKET MILK

Module 3. Clean milk production

Lesson 5
MILKING PROCESS AND ENVIRONMENT

5.1 Practices Related to the Milking Process

5.1.1 Udder washing

• All udder washing and cleaning should be done gently so as not to damage the orifices and clefts between the quarters of the udder.

• For all washing, two buckets (one with plain water and a second, which carries the disinfecting solution) with two separate cloths for both the purposes are required. A third bucket with a mild detergent solution and a third cloth is recommended for wiping the teats after milking.

• The first wash with tepid water should remove all dirt particles from the udder. A gentle detergent solution may be employed to remove persistent dirt. If the dirt is wiped off with a wet cloth, the cloth should be wrung outside the bucket.

• During severe winters, lukewarm water is recommended for udder washing to avoid chills. This also conditions the animal to let down the milk. The temperature of the wash water should be below 55°C.

• Addition of hypochlorite solution (500 ppm) helps to disinfect the udder. Solutions of quaternary ammonium compounds (200 to 400 ppm) are better substitutes due to their less harmful effect on tissues. Under Indian conditions, the easily available Dettol or Savlon may be diluted as per the manufacturers’ instructions and used to disinfect the udder and teats.

• After washing, these organs should be dried before milking. A different wash cloth as well as drying cloth is recommended for each cow. The towel used should also be washed after each milking and disinfected by boiling from time to time.

• Disposable paper towels may be used instead of cloth. However, under the Indian conditions, these may be impractical.

• The udder and teats should be wiped with clean cloth dipped in detergent solution after milking.

5.1.2 Hygienic practices during milking

• The milking should be complete, with no milk left in the udder after milking.

• The first few ml of milk should be discarded, as this contains a large number of microorganisms.

• This forestripping should be collected in a cup or a utensil and not thrown on the floor, so that flies and other insects may not be attracted towards it.

• Milking should be done with full hands, quickly and completely, followed by stripping, if so required. Milking operation should be complete in 7-8 minutes. In farms with more than 8 high-yielding cows, it is preferable to use a milking machine. If the herd exceeds 100, a separate milking parlour will ensure better hygiene.

• Unhygienic practices such as dipping the fingers in milk and then wetting the teats to soften them should not be permitted.

• Milking with the full hands and not with the knuckles is preferred as the latter leads to more chances of teat injury.

• Sick cows should be milked at the end to prevent infection.

• The animals should be dried off 60-70 days before calving.

5.1.3 Hygiene of milking utensils

• All milking utensils should be of uniform size.

• They should have small mouths to avoid external contamination.

• They should be made of a non-rusting and non-absorbent material such as aluminium or galvanized iron. Stainless steel would be ideal, but for the cost considerations. The use of vessels such as empty dalda tins, pesticide/insecticide containers, teapots etc. should be avoided.

• The utensils should be free from dents, cracks and crevices.

• The utensils should be scrubbed and cleaned before and after each milking.

• The detergents and chemicals used should be non-injurious to health, and non-abrasive to hands. At farm level, use of washing soda coupled with exposure to sunlight or rinsing with scalding water or use of detergents-cum-disinfectants such as iodophors is recommended.

• The cleaned vessels should be placed inverted for complete drainage of water after milking, so as to avoid contamination from bacteria of the air, insects, rodents, mosquitoes, reptiles etc.

• In villages where milk collection is carried out by co-operative societies, the use of community milking byres/parlours with facility to clean and disinfect udders/teats as well as milking equipments under the supervision of the society officials is recommended.

• Milk should immediately be transferred from the barn to an appropriate place.

5.2 Practices Related to the Environment

5.2.1 Hygiene of milking environment

The places, where housing, feeding and milking of the animals are done, need special care in order to minimize contamination of the milk. In the animal house system, the animals are housed during winter and milked in the same building. This system has been practiced in temperate countries for many years, the extent of its adoption varying in different countries according to climatic conditions. The animal house is a specialized building, which should be carefully designed and constructed so as to provide comfortable and healthy housing facility for the cows and at the same time to enable them to be milked in clean conditions.

The animal house should be situated at an appropriate site. Water should be available in plenty and drainage facilities must be there. There should be ample ventilation in the shed with enough space to house all the animals. Proper drainage system is an essential feature of every animal house to facilitate collection and disposal of liquid wastes so as to prevent contamination of milk. There should be isolation boxes or separate accommodation for sick animals and animals about to calve.

5.3 Feeds and Milk Contamination

Clean milk production must also ensure that feedstuffs offered to animals are not a potential source of contamination. Proper nutrition can decrease new mammary infection rates by improving the animal’s immunity. The usefulness of antibiotics and drugs against mastitis and other diseases in animals have rendered them almost indispensable in veterinary medicine. The administration of these substances, however, results in the secretion of their residues into milk. The consumption of such contaminated milk has physiological and technological implications. Once antibiotics and drugs find their way into milk, it is difficult to get rid of them. Heat treatment is not usually effective. Processes such as ultrafiltration (UF) can help considerably, to reduce the antibiotic load of milk. Use of specific enzymes (such as penicillinase to inactivate penicillin) may be useful in salvaging all components of the contaminated milk, albeit, at some extra cost. However, under the Indian scenario, the best and more economical method would be to follow stringent preventive measures listed below.

• Antibiotic administration to infected animals should only be done under veterinary supervision.

• Clinical cases should be treated as soon as they occur.

• Cases of sub-clinical mastitis should be treated at herd level at the beginning of the dry period.

• Each preparation of antibiotic used for the treatment of milch animals should be tested for determining the maximum interval before all traces are secreted.

• The appropriate withholding time, usually 72 h should be observed.

• Regular monitoring of the raw milk supplies by means of suitable test method and penalties for the delivery of contaminated milk is essential. (Unfortunately, there are not enough inexpensive farm level tests that may be used to detect extremely low levels of residues that sophisticated tests are capable of detecting).

The use of pesticides to control any pest, including unwanted species of plants or animals during the production, storage, transport, distribution and processing of food, agricultural commodities and animal feeds leads to the retention of these products or their derivatives in the product. Such residues pose serious threat to public health by entering into the milk when these materials containing pesticides are used as cattle feed. Organochloropesticides (OCP) including DDT (dichlorodiphenyl trichloroethane), BHC (benzene hexachloride), chlordane, heptachlor, aldrin, dieldrin, endosulphan are fat soluble, persistent and not readily excreted by the animals except into milk. Being insoluble in aqueous media, they are unavailable for microbial degradation or detoxification. They remain stored in the animal body fat for long periods in an unchanged form. These pesticides are metabolized at the time of lactation or stress and transported into the milk. The toxicological effects of consuming food products containing pesticide residues include cellular and genetic damage to animals and human beings, blindness, tumerogenic effects, damage of liver function, premature onset of labour, intra-uterine growth retardation and infant mortality.

Selected Readings

Singh, R.R.B., Sabikhi, L., Patil, G.R. and Sharma, N. 2003. Clean milk production – Strategies and interventions. NDRI Publication No. 10/2003.
Wadhwa, B.K. 2000. Pesticide residues in milk and milk products: Safety aspects of quality assurance. Indian Dairyman. 52(3): 17-20.
Yadav, J.S., Grover, S. and Batish, V.K. 1993. A Comprehensive Dairy Microbiology. Metropolitan, New Delhi.