When selecting a feeding programme for your calves there are pros and cons to consider before making the move: disease risk, nutrient intake for growth performance, and economics. You may think that pasteurisation is the best option for your system and so it may be, but it might be worth reading on to consider some of the myths about pasteurising.
What is the purpose of pasteurising
The purpose of pasteurising is to heat the milk to a temperature that safely decreases the pathogens in the milk. Most commonly used on farms in the UK is batch pasteurisation and when the temperature reaches 65.5°C and is maintained for 30 minutes it is suggested that this is adequate time to destroy 95.5% of the diseases and pathogens whilst keeping the important nutrients intact. (Stabel, 2001)
Myth 1 - ‘Pasteurising whole milk kills 100% of the bacteria’
Wrong. Pasteurising is a great way of improving the quality of your milk, but bacteria can still be present even after pasteurisation. Although pasteurisation reduces the microbial load it is not sterilisation!!
And a high bacterial load in your milk will not be eliminated by the process (Taeasg, 2020). If not stored correctly after pasteurisation bacteria will grow rapidly, therefore, cleanliness, sterilisation and good milk management are essential. If there is to be a delay between pasteurisation and feeding then cooling the milk in temperatures between 10-20°C is essential, the bacteria in the milk will begin to replicate in the warm weather if this process is delayed. (Holm & Laue 2020)
Myth 2 - ‘Calves get all the best nutrients from pasteurised milk’
Wrong. One of the main benefits of feeding CMR is consistency. The fats, proteins and solids can vary significantly in whole milk, making it difficult for the calf to maintain a consistent diet, this can cause digestive upset for the calves. Consider using a Brix refractometer to determine the solid content of your whole milk.
It is recommended to add two points to the value of your Brix reading. So… if the number on the Brix reading is 10.5 it would be advised to add 2.0 which would bring your solids to 12.5. It is important to check this on a daily basis to ensure there is no high variability. The suggested quality goals are shown in the table below.
| Parameter | Goal |
| Standard plate count | <20,000 cfu/ml |
| Total solids | >12% |
| Fat | >3.5% |
| Protein | >3.0% |
Table 1: Quality goals of pasteurised waste milk fed to calves
(Hubbard Feeds, 2018)
Myth 3 - ‘It is cheaper to feed pasteurised milk’
Consider the costs. The costs of collecting milk, pasteurising, and storing milk before and after pasteurisation must be evaluated before you consider installing pasteurisation equipment. The capital cost must be assessed, cost will vary depending on the pasteuriser choice, size and capacity along with which manufacturer you choose, not forgetting the cost of electricity and water once installed, it costs approximately £0.56/day to run the pasteuriser (e.g. water, heating).
Things to consider:
- Is the existing hot water heater working (and is it hot enough)?
- Are there any special electrical requirements?
- Water supply
- Drainage requirements
- Purchase and installation costs
- Training farm staff to properly use and clean the equipment
- Time/labour to use and clean equipment
- Variable costs
- Servicing
- Moving and storing milk before and after pasteurisation
- Monitoring performance
Myth 4 - ‘Pasteurisation eliminates the trace of antibiotic milk’
Wrong. If deciding to use pasteurised waste milk, maybe you should think about this one. Antibiotics are not affected by pasteurisation, be careful because calves can develop an antibiotic resistance.
One study showed that calves fed pasteurised waste milk had an increase in antibiotic resistance compared to calves fed whole milk, it can also be unpalatable to the calf, increasing the concern of poor calf growth.
Summary
Feeding pasteurised milk can be a good source of nutrition for calves which, if fed correctly, can produce a low cost, high-value feed for calves. Success in pasteurising whole milk is the ability to control the milk before and after pasteurisation to avoid contamination. Considering all of your options and weighing out the pros and cons is important to make sure this is the right decision.
