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Benefits and drawbacks of feeding pasteurized milk to calves

Ellan Dufour for Progressive Dairy Published on 06 November 2019

When selecting a liquid feeding program for growing calves, there are benefits and drawbacks to consider, including nutrient intake targets for growth goals, program management, economics and potential disease risks.

Pasteurized whole milk is an option that can be used for a dairy calf’s liquid diet. This whole milk can be sourced on-farm from the saleable bulk tank milk, transition milk, mastitic milk and other non-saleable antibiotic-containing milk. Pasteurizing and feeding non-saleable milk – essentially waste milk – can be an effective, cost-efficient method for utilizing an otherwise unusable product, provided it can be managed properly.

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How pasteurization works

A primary concern when feeding waste milk to calves is the bacterial load that may be present in the milk. Pasteurizing waste milk has been recommended in order to reduce bacterial contamination and limit the spread of diseases that can be transmitted through milk. Pasteurization is a method of exposing this waste milk to specific temperatures for specific amounts of time in order to dramatically reduce the pathogen load prior to feeding. (See Table 1.)

Pasteurization time and temperature guidelines

It is important to note that pasteurization is not a sterilization technique. Recent research has demonstrated that any remaining bacteria in pasteurized milk has the ability to proliferate to exponential levels if holding temperature and/or feeding time is mismanaged. Additionally, pasteurizing highly contaminated milk may allow certain varieties of viable pathogenic bacteria to survive the pasteurization process.

Types of pasteurizers:

  • Batch pasteurization uses a vat or tank with a heating element that heats the milk. Agitators are used with batch pasteurization to eliminate cold spots within the tank. This system typically heats the milk for longer periods of time at lower temperatures, as compared to high-temperature short-time (HTST) units. Thereafter, milk is cooled and can be fed to calves.

Advantage:

  • Low-cost

Disadvantages:

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  • Large batches may take several hours to pasteurize
  • Manual cleaning process
  • Continuous flow or HTST pasteurization circulates milk through a network of heated coils for a rapid increase in temperature. This HTST system can be equipped to rapidly cool milk to feeding temperature once pasteurization is achieved.

Advantages:

  • Rapid pasteurization

  • Cleaning process may be automated, using a system similar to that used in milking systems

Disadvantages:

  • Expense
  • Requires an adequate supply of hot water
  • Colostrum pasteurization is typically done in a batch pasteurizer held at 145 degrees Fahrenheit for 60 minutes to effectively kill bacteria while also preserving high-quality colostrum components. Both time and temperature parameters for colostrum pasteurization should be carefully followed. When compared to raw milk, colostrum is extremely high in both protein and fat content. High-temperature, short-time pasteurizers will denature important proteins, such as immunoglobulins, and will thicken colostrum, making cleaning and maintenance of the system very difficult to impossible.

The benefits of feeding pasteurized waste milk:

  • Reduced disease transmission: Heating milk to 161 degrees Fahrenheit for 15 seconds is effective at killing Staphylococcus, Streptococcus, Salmonella, E. coli, Listeria, Mycobacterium paratuberculosis (the organism responsible for Johnes disease) and Mycoplasma bacterium. Reducing bacterial exposure to calves can lower morbidity and mortality rates while also reducing the opportunity for pathogens to spread throughout a calf barn.

  • Utilization of waste milk: Unless fed to calves, waste milk is seen as a loss to dairy producers. Utilizing waste milk to feed and raise calves allows producers to avoid potential economic losses, disposal challenges and environmental concerns that may arise during the discarding process. The profitability of a pasteurization system is dependent upon many factors, including labor, equipment, installation, maintenance, energy costs, number of calves, amount of waste milk available and other variable costs.

  • Opportunity for improved calf health and performance: Calves fed pasteurized milk have fewer scouring days and respiratory problems when compared to calves fed unpasteurized milk due to the significant reduction in pathogen load. Studies also show calves fed pasteurized milk have greater average bodyweight gain than calves fed unpasteurized milk.

The drawbacks of feeding pasteurized waste milk:

  • Intensive management required: Compared to a milk replacer feeding program, feeding pasteurized milk to calves requires thorough research on what type of pasteurization system is best suited for the farm prior to purchase. Infrastructure needs to be considered in order to properly harvest, store and transport both pre- and post-pasteurized milk, to avoid contamination and reduce pathogen load. Strict pasteurization, sanitation, maintenance and monitoring protocols need to be set up and strictly followed.

  • Failure of pasteurization: Routine monitoring of the system is vital to ensure failure of pasteurization is avoided. Pasteurization failure can occur due to a number of causes, including human error, malfunctioning and/or contaminated equipment, heating and cooling inadequacies or unusually high bacteria counts in the pre-pasteurized milk. If fed to calves, improperly pasteurized milk can quickly lead to calf morbidity and mortality.

  • Inadequate waste milk supply: Due to the inconsistent and sometimes unpredictable number of cows producing waste milk, and the number of calves fed milk at any one time, there may be times when the supply of waste milk available for all calves is inadequate. As such, it is imperative to have a strategy in place in the case the waste milk supply may be limited. Options available include utilizing a milk replacer, a milk extender or pasteurizing saleable milk. Older calves are more tolerant of diet changes than young calves. A common suggestion is to switch the diet of older calves during waste milk shortages, with the goal of limiting diet changes as much as possible in order to avoid digestive upset in younger calves.

  • Inconsistent nutrient composition: Unlike milk replacer, the nutrient composition of waste milk is variable. This inconsistency has the ability to cause digestive upset in calves, especially in young calves. The suggested quality goals of pasteurized waste milk are found in Table 2.

Quality goals of pasteurized waste milk fed to calves

  • There are several products in the market that work to mitigate the inconsistent nutrient composition of waste milk, which include:

Fortifiers: increase the vitamin and trace mineral content which is often deficient in whole milk. Medicated and non-medicated additives are typically optional.

Extenders: increase total milk volume if waste milk supply is short. Extenders also provide additional vitamins, trace minerals, protein, and fat. Economical milk replacers are often used as extenders. Medicated and non-medicated additives are typically optional. Pasteurized milk with high bacterial counts should never be fed to calves in the event of inadequate waste milk supply.

Balancers: high protein, low fat product that alters the protein-to- fat ratio of waste milk, resulting in increased protein. Often fortified with necessary vitamins and trace minerals with medicated and non-medicated options available.

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Pros and Cons of pasteurizing & feeding waste milk to calves

There isn’t a one-size-fits-all option when it comes to selecting a liquid feeding program for growing calves. Major factors to consider when establishing a program should include targets for nutrient intake in relation to growth goals, ease of managing the program, economics and potential disease risks.  end mark

References omitted but are available upon request. Click here to email in editor.

Ellan Dufour
  • Ellan Dufour

  • Dairy Research Nutritionist
  • Hubbard Feeds
  • Email Ellan Dufour

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