Animal Health & Welfare
- Dairy cow welfare strategy
- Biosecurity and diseases
- Cow Culling
- Pathogens - The cause of mastitis
- Symptoms of Mastitis
- Working Arena - prevention of infection
- Breeding & Genetics
- Business Management
- Grassland Management
- People Management
Plant cleaning routine
Effective post-milking plant cleaning is essential in controlling Bactoscan readings by removing bacteria and milk residues from internal plant surfaces, but also has an important function in controlling the pathogens that can cause mastitis, particularly in systems where high cell-count and mastitic cow groups are milked last. Poor cleaning techniques are likely to result in the spread and proliferation of pathogens from one milking to the next, particularly those bacteria capable of surviving higher temperatures and those which can colonise poorly-sanitised internal plant surfaces where cleaning has been ineffectual.
For effective cleaning and disinfection it is advisable to perform the full hot wash routine after every milking, and not just on a once-per-day basis. All the water used in the washing routine must be of drinkable quality, or it may harbour bacterial contamination.
Modern high-throughput parlours with wide-bore pipes require particularly-efficient cleaning systems; some of these are automated but they still require checking to ensure than the system is operating adequately. Systems are also fitted to ensure than all internal surfaces are cleaned properly; they produce turbulence in the washing solution and introduce 'air slugs' into the wash and must be switched off during milking.
The post-milking routine is best performed immediately milking is completed, before milk deposits begin to form; this takes advantage of the residual heat in the system from the milk flowing through the pipes. British Standards stipulate a minimum of 18 litres of hot water per milking unit for plant washing and having sufficient boiler capacity - and timing hot water production - is crucial. Sanitizing external surfaces in the parlour such as the cluster units is also important in reducing mastitis pathogens and other bacteria.
In the UK circulation cleaning is the more popular means of parlour cleaning, and it is comprised of several steps:
- Residual milk is drained from the pipes into the bulk tank.
- A rinse cycle of warm water at around 40°c to wash any further milk residues from the pipes, which is cycled once and run to waste. Enough water should be used to ensure the rinse water runs clear before the next stage in the process. Cold water is not ideal as it allows residues to congeal in the pipes and removes essential heat from the plant.
- A wash cycle using a chlorinated alkaline detergent which can break down protein and fat deposits so that they can be removed from the system, carefully following the manufacturer's instructions. Generally, hot water around 70°c is cycled through the plant until it exits the system at that temperature. Then sufficient detergent should be added and the solution circulated for five to eight minutes at 60-70°c. If water nearer the boiling point is used it may render the detergent less effective at removing protein deposits, and at temperatures below 40°c, fat deposits begin to solidify and form inside milk pipes. To avoid the build-up of mineral deposits, the alkaline detergent should periodically be replaced with an acid-based milkstone remover, particularly in hard water areas.
- A cold rinse, which may contain a disinfectant; usually sodium hypochlorite if none is present in the detergent. A maximum concentration of 50 parts per million of hypochlorite should be used as higher concentrations will damage parlour rubberware. Enough clean water should be used to ensure that the hot wash solution has been washed out of the plant.
An alternative acid boiling wash may be used, where water over 96°c is used, cycled once and run to waste with dilute nitric of sulphanilic acid added to prevent deposit build-up. This method is quicker and uses fewer chemicals but is unpopular in the UK due to the cost of heating large amounts of water.
Dump buckets, lines and separate cluster units used for milking mastitic cows or those undergoing antibiotic treatment should not be overlooked. In some systems they may be included in the plant washing routine but are usually washed by hand. This means that their cleanliness can be checked, as they are important items which are implicated in the spread of mastitis pathogens.
The correct function of the washing equipment is part of a dynamic milking parlour test. It is important to regularly check that the system is functioning correctly; for instance, that the jetters are not worn, broken or blocked; and that airlines are washed twice yearly, as stray milk may occasionally enter them.
Most bulk tanks are fitted with automated washing systems to be used every time they are emptied but their efficacy should not be taken for granted.