Most operations that feed waste milk to calves need to extend or supplement their supply of whole milk, at least periodically. They may have a variable or limited supply of waste milk or they may be looking to ensure a minimum solids level with each feeding. Consequently, they still have a need for a milk replacer type of product.
Formulations of these products vary depending on the farm's objectives. An old standard is a 20% protein, 20% fat milk replacer that can be blended with waste milk and water to extend the supply, or it can be fed directly to calves when the waste milk is used up. Variations on this approach include 22-22 and 24-24, each with a slightly different effect on the protein and fat levels of the final mixture when added to waste milk.
Another approach is to measure or estimate the protein and fat in the farm's waste milk and have a custom formula made to approximate that analysis. This approach attempts to minimize variability in protein and fat from one feeding to the next. Alternatively, a 25-15 is used to match the protein level of waste milk while lowering the fat level in the final mix. An objective here would be to enhance the intake of starter feed.
Extenders and fortifiers provide a special opportunity to take advantage of non-milk proteins. The use of certain non-milk proteins in milk replacer formulas has long been a way of reducing cost while maintaining growth and performance. In this application, since the extender is not the complete diet and is mixed with another milk source, the percentages of non milk proteins such as egg, plasma or wheat can be increased above the normal milk replacer limits, further reducing cost. These specially formulated products should not, however, be fed directly to calves as their only source of nutrition. The level of non-milk proteins may be too high for them to be fed as regular milk replacers.
Regardless of the formula, there is an inherent source of variability when using these products, namely how much water is added along with them. To minimize this variability, many operations use a refractometer to measure total solids in the waste milk and then add the correct combination of water and milk extender to achieve a specific solids level in the final mix.
A refractometer tends to underestimate the solids in non-homogenized whole milk such as waste milk or milk from the bulk tank. A common practice when measuring these fluids is to simply add "2" to the refractometer results.
Whole Milk Extender & Fortifier Calculator
Managing daily variation in total solids of waste milk is much simpler than trying to manage fluctuations in protein and fat. In many situations, the amount of waste milk available and the number of calves that need to be fed change frequently. Figuring out how much powder and how much water need to be added to today's supply of waste milk to adjust total solids for today's number of calves takes a bit of calculating. With a few pieces of information you can do this by hand... or you can use a calculator like the one below, where the formulas are already plugged in and ready to go.
All you do is enter the required values in the red cells and the calculator does the rest. The right arrow points to the results of the calculation, showing how many gallons of water and much powder must be added to the available waste milk to feed those calves for one feeding.. The down arrow points to those results in a chart which is more of a quick reference that shows what to do at various calf numbers and various amounts of waste milk.
Additives. The calculator also lets you choose to include two additives. ClariFly to help with fly control during the summer months, and 7-60 fat, a supplemental energy source for winter months. The inclusion levels of these additives are based on the manufacturers' recommended feeding rates.
Note: negative numbers may show up in the table. In this case, there is excess waste milk for the number of calves and you can't adjust solids appropriately unless you reduce the amount of waste milk being fed.
Using a calculator like this makes the job of calculating daily mix ratios a simple task. You can take the chart out to the mix area for quick reference or work with it in the office to explore different scenarios and determine your future needs.
Download a working copy of the Whole Milk Extender & Fortifier Calculator
If you are interested in tools for economic evaluations of on-farm pasteurization and feeding options you might want to check out Penn State Calf Milk Pasteurizer Evaluator
(updated Jan 15, 2015)