The move to chlorine-free cleaning detergents in milking parlours and bulk tanks has not been without its challenges.
A rise in total bacterial counts (TBC) and thermoduric bacteria has been observed on plenty of farms, despite a huge effort by farmers and milk quality advisers on addressing the issues.
High levels of bacteria in milk reduces the processing quality of that milk.
Thermoduric bacteria are heat-resistant, meaning they survive the pasteurisation process, which then reduces the shelf life of the products made with the affected milk.
Different processors have different standards but all processors either penalise high bacterial counts or incentivise low bacterial counts.
High bacterial counts indicate poor hygiene
Typical requirements are for milk to have a TBC of less than 30,000 cfu/ml and a thermoduric count of less than 300,000 cfu/ml.
High bacterial counts indicate poor hygiene. This bacteria can come from either the milking equipment itself or from the cow through dirty teats.
Chlorine was a very effective cleaning agent but since it is no longer allowed to be used in cleaning milking equipment, some farmers are finding that bacterial counts are creeping up, which would indicate that the milking equipment is the problem.
However, chlorine-free wash programmes may not be the only cause for this, so it’s no harm to evaluate cow-related factors first.
This is especially true in the case of thermodurics, as soil-contaminated teats are seen as a major factor in high thermoduric levels.
If washing teats, it is essential that they are dried also
Bacterial levels on teats tend to increase in wet weather when cows are dirtier with soil and faeces on legs, udder and teats.
In these instances, cleaning and drying the teats before milking may be necessary where a problem needs to be tackled.
If washing teats, it is essential that they are dried also. Otherwise, bacterial levels in the milk could increase as wet teats will make the bacteria more mobile.
Hot and dry weather, like that experienced in July, can also be a problem for thermoduric levels, particularly when cows are grazing tight and close to the soil surface.
More often than not, the main problem is due to some issue in the plant and/or the bulk tank.
The first port of call should probably be the bulk tank – is it washing correctly and using the correct amount of detergent? Is it cooling the milk quickly enough? Are there too many partial milk collections, meaning it’s not getting washed often enough? Is the water hot enough and is there enough of it in the wash cycle?
Milk advisers or service technicians can advise on how to adjust the settings on the bulk tank to take in the right amount of product
The changeover to chlorine-free wash routines has meant the amount of product required to be sucked up by automatic wash units on bulk tanks has changed.
Milk advisers or service technicians can advise on how to adjust the settings on the bulk tank to take in the right amount of product.
It’s important to check and calibrate chemical uptake rates regularly as, sometimes, chemical tubes can get blocked. This is a common problem with chlorine-free products as the viscosity of many of these products is greater, meaning they are slower to move in the pipe. Another common issue is the chemical drum running empty and not being observed until there is a problem. The use of clear drums or sensors can help with this.
According to some milk quality advisers, when it comes to the plant the common denominator in most problem cases is insufficient hot water. This is usually a combination of not enough hot water or having plenty of water but at too low a temperature.
In terms of volume, the requirement is for 9l to 10l of hot water per unit. So a 16-unit milking parlour will require between 144l and 160l of hot water.
The starting temperature should be 750C to 800C, the mid-cycle temperature should be 550C to 650C and the end cycle should be 450C to 550C after eight to 10 minutes of circulating time.
A common problem is for hot wash circulation times to be too long. This results in the hot water removing milk stone and other deposits only for these to be re-deposited as the wash starts to cool down again.
A trick commonly used to increase the temperature in the hot wash cycle is to pre-heat the pipelines with warm or hot water before starting the hot wash
Best policy is to complete a task during the hot wash cycle that takes 10 minutes and when that task is complete, move to the rinse cycles. At least then the wash times will be consistent and not too long.
A trick commonly used to increase the temperature in the hot wash cycle is to pre-heat the pipelines with warm or hot water before starting the hot wash.
This can be done as part of the initial rinse or as a secondary rinse with a smaller quantity of water.
This warm rinse increases the temperature of the pipework, so less heat will be lost in the main hot wash.
Alternatively, let the first 15l to 20l of the main hot wash run to waste before adding the chemicals to the wash trough. The first 5l of the wash should run to waste as this will contain a high proportion of deposits and shouldn’t be re-circulated through the system.
The requirement for extra hot washes for chlorine-free wash routines is putting extra pressure on water heating systems and adding extra cost on to farmers.
Teagasc says that water heating accounts for 23% of energy use on dairy farms. There is always debate around the best system for heating water.
In Britain and New Zealand, it is more common to find gravity-fed water heaters for providing hot water
Teagasc says that for the majority of farmers, electrical water heaters on night-rate electricity will be optimum in terms of installation and running costs where up to 300l of hot water is required daily.
One of the problems with many of these electric water heaters is that as hot water exits the tank, cold water enters which tends to lower the temperature of the water in the tank.
In Britain and New Zealand, it is more common to find gravity-fed water heaters for providing hot water.
These are generally sited above wash troughs meaning the wash troughs are filled quickly with hot water and there is less opportunity for the water in the tank to be diluted with cold water.
The key requirement when considering instant water heating is to have adequate flow rate
Instant hot water systems do away with the need for hot water to be stored.
These systems usually use gas or oil burners to instantly heat water to the required temperature.
The key requirement when considering instant water heating is to have adequate flow rate. Gas boilers typically heat water to 850C at a flow rate of 12l/min, meaning it would take 15 minutes to produce 180l of hot water. Therefore, additional heaters will be required or else the water in the trough will be too cold.
Cleaning the vacuum line is a task that should be carried out at least twice a year and/or whenever there is a TBC problem.
Dirt and contamination can enter the vacuum line during the wash cycles or if the receiver jar floods, or more commonly through a damaged milk liner or holes in the pulse tubes.
Over time, bits of debris and milk or muck can build up in the vacuum line and re-enter the milk through the sanitary jar
There should be a drain valve on the lowest point on the vacuum line that allows liquid to drain away. This should be closed when the machine is on but open when the machine is off. If water or milk is seen coming from this, it could indicate a cracked liner.
Over time, bits of debris and milk or muck can build up in the vacuum line and re-enter the milk through the sanitary jar.
Cleaning the vacuum with a hot detergent solution followed by a cold water rinse will help to prevent this from happening. Where more solid dirt has built up, the vacuum line may need to be dismantled and cleaned by a push-through pipe cleaner.
Check the operator’s instructions for how to clean the vacuum line but most types of machines have a valve at the furthest away point, which allows for liquids to be sucked in.
Don’t suck in any more than about 75% of the capacity of the interceptor jar. Otherwise, you risk damaging the vacuum pump. Turn off the machine to let the wash solution drain away before rinsing.