What should be done to have clean milk?

Griffin Kosgei milking his Dairy cow at his farm in Ngata, Nakuru county. [Kipsang Joseph, Standard]

Dear Daktari, Thanks so much for your good articles on animal production and health. I like how you simplify otherwise technical topics into a very readable language. Kindly educate us a little bit on how to handle milk to avoid contamination. [George Kambaki, Maralal]

Thanks, George, for reading the Smart Harvest and also for your good question. Milk is a very sensitive product and there are various points during its production, handling and storage where contamination can happen. It is important to identify these points and put in place control measures to avoid contamination. 

Fecal particles from soiled teats, udder and the tail switch. The person doing the milking or handling milk after milking can also be a source of contamination through soiled hands or dirty milking equipment and dirty environment where the animal lives or where the milking takes place. 

Because the animal itself can be a source of contamination; the first step in ensuring clean milk production is by keeping the animal clean. Then the area where the animal is kept should also be clean, have sufficient space and with good aeration and ventilation. The building should be designed in a way that the fecal waste is quickly drained away.

Environmental pathogens are a main source of mastitis in herds. Environmental bacteria (such as E. coli and the environmental streptococci) are often present in organic bedding sources and wet, muddy cow shades. Animal Husbandry practices that reduce teat end exposure to these organisms will reduce the risk of developing mastitis. Bedding sources that are clean, dry and comfortable will minimize pathogen growth. Inorganic bedding such as sand is often the best choice for reducing pathogen numbers. 

It should be a routine practice to examine milk from individual animals separately before mixing them if you are milking from more than animal. Only animals in good general health status and specifically udder health must be milked. If you suspect an animal is sick; it should be milked last. Thoroughly sanitize after each milking.

Milk from these animals must not be used for human consumption. Before the milking process ensure that the udder, the teats and adjacent parts are cleaned with warm water. Further cleanliness can be assured through removal of udder hair. It is a good practice to routinely remove udder hair once a month or more often if necessary. Cleaning of teats before milking helps to remove both visible soiling (faeces, bedding, mud, residual post milking disinfectants) and bacteria which could contaminate the milk. Dry wiping is not recommended as research shown that this method removes very few bacteria.

Fore-milking milk from each animal must be checked for physical/chemical/organoleptic abnormalities. Fore-milking assists early detection of mastitis; removes potentially contaminated milk from the teat canal and stimulates milk let down. Fore milking is adequate if 2-3 streams of milk are expressed.

Last but not least do not milk animals that are undergoing medical treatment and which are still within the prescribed withdrawal period. Low temperatures are used to preserve milk. This should be done immediately after milking by cooling it to 8 0C . This avoids the growth and multiplication of bacteria that cause spoilage. 

Post-milking teat disinfection reduces the transmission of contagious mastitis pathogens and is still widely used. Finally, the last step in an effective milking routine is to ensure that the cows remain standing for at least 30 minutes after milking is completed fresh feed can be given to encourage this behaviour.

[Dr Othieno is a veterinary surgeon and currently the head of communications at FAO-Kenya. The views expressed here are his own]