Low grade or unclean milk normally results in losses. The milk can end up getting spoilt or rejected if one sells to processors as it is unfit for human consumption.
Clean milk should not:
a) Have impurities such as hair or dust.
b) Have odour or any other colour besides white.
c) Have pathogenic organisms that may cause diseases to both human beings and animals.
d) Have chemical residues, especially those used at the farm such as antibiotics and pesticides.
e) Exceed the legal minimum requirement for water (87.3 per cent), butterfat (3.8 per cent) and solid non-fat (8.9 per cent).
In many cases, farmers or farmhands contribute to the contamination of milk.
The main sources of impurities are:
a) The animal: Much of the dirt that goes into milk comes from the cow’s flanks, udder or belly during milking. Therefore, the animals should be clean always to avoid contamination. In addition, the dairy herd should be free from diseases that might spread through milk, for instance, brucellosis. Drug withdrawal periods must also be observed.
b) Milk handling and storage equipment: Milking equipment should be kept clean. When cleaning, equipment should first be briefly rinsed then thoroughly washed before final rinsing to avoid formation of germ-harbouring ‘milk stones’ (denatured milk protein) on the equipment.
c) Environment (especially around the milking parlour): The milking facility should be located in a well-drained area and kept clean.
d) Milkers and milk handlers: All the personnel handling milk must be clean and free of communicable diseases.
The milking programme
A good farmer must have a milking programme and stick to it if he is to get the best quality and quantity of milk. The milking methods should also promote a long productive herd life. The milkers must understand and like the cows to apply proper milking procedures.
A skilled milker should be able to notice if a cow has any problems on the udder, if the animal is on heat or that which feeds less and failure of the milking machine to function properly. The milking process should be organised this way:
The cow should be assembled 15 to 30 minutes before milking starts.
Restrain it using a rope, neck yoke and or hook.
Milking equipment, utensils and feeds should be assembled at conveniently accessible spots to reduce movements during the actual milking process.
Prepare the udder by washing with warm water, testing for mastitis (using a strip cup) and wiping both the teats and udder dry using a clean towel.
Place feeds into the trough if the cows have been conditioned to feed while being milked.
The milking proper is then performed using hands or machine. Be organised so that the session is fast, effective and efficient for higher productivity.
Use the squeezing technique to empty the udder. If stripping is applied, it increases the somatic cell count in the milk besides weakening the teat’s sphincter muscles and irritating the milk canal increasing chances of pathogenic infections.
When squeezing, start with teats in the rear quarters since they give about two-thirds of the total milk per session. The udder should always be emptied completely otherwise subsequent milk production may decline.
Weigh and record the yield before sieving the milk into a holding can for transportation or cooling.
Apply milking jelly on the teats and or immerse them into a teat dip and release the animal.
Using machine milking
Turn on the vacuum supply.
Hold the claws in such a way that they are at one level and the teat cups hang freely downwards. Then place the cups onto the teats starting with those far from you.
When milk flow stops (as seen from the transparent part of the claw), turn vacuum supply off promptly then remove one teat cup. At this point, the cups will slide off the teats easily.
Clean the teat cups by dipping in water to remove milk inside the liner before using them on another cow.
Machine milking is cost-effective as it leads to the reduction of labour costs, reduces incidences of diseases and maintains the shape of the teats and udder.
However, the method comes with high initial costs, can be a source of infection if poorly maintained, requires knowledge of mechanics to operate effectively, works well with cows that have medium-sized teats and udder and it may be hard for a farmer to know the amount of milk produced by each teat or quarter.
Milk production reflex
To make the cow produce more milk, maintain the milking time, be friendly to it — if possible let it recognise the milker — wash the udder, allow brief suckling by the calf and let the animal feed as you milk.
Milk synthesis takes place in the alveoli region of the udder whence water, mineral salts, vitamins and sugar (lactose) are secreted by cells into the alveoli sac with the excess flowing into milk ducts.
The main milk letdown reflex involves activation of the nerves in the skin of the teat that are sensitive to touch and temperature. Neural impulses ascend the spinal cord to the brain where they stimulate the discharge of oxytocin into the blood stream.
The hormone diffuses out of the capillaries in the udder and causes contraction of myo-epithelial cells that surround the alveoli and smaller ducts. The squeezing action forces milk through the ducts to the gland and teat cisterns.
Contraction of the myo-epithelial cells occurs from 20 to 60 seconds after stimulation of the teats. Milking should commence a minute after the initial stimulation. After release into the bloodstream, the effective level of oxytocin lasts for only seven to 10 minutes.
Thus it is important to draw the milk rapidly within this period. On average the entire process should last eight minutes. Ill- treatment, rough handling and or a strange environment should be avoided prior to and during the milking process.