It’s the ultimate recycling story -- one that could boost a dairy farm’s sustainability and possibly even carbon credits, while maintaining excellent nutrition and production. Feeding liquid whey could be the way to bundle these multiple benefits in one package.
Whey is a co-product from cheese and yogurt production, and it’s often readily available in dairy-concentrated regions where dairy manufacturing is centered among the cows. It was once considered a total waste product, until value-added processing techniques converted and stabilized it to capture its nutritive merits in more portable and storable forms.
Now, dried whey powder, permeate, and whey protein concentrate are widely used in everything from pet food to calf milk replacer and baked goods to bodybuilding supplements.
But due to logistics and storage challenges, an estimated 40-50% of whey produced in the U.S. is still discarded – often discharged as sewage. In addition to wasting nutrients, this practice can create a high biological oxygen demand that must be managed carefully to prevent water pollution.
Enter the humble dairy cow. She produced the original foundations of whey, and she can consume and recycle the elements that remain. In terms of dairy nutrition, whey is a highly concentrated energy source because it is made up of 60-70% lactose. It also provides a moderate amount of protein (6-8%) and is rich in calcium, phosphorus, sodium, and potassium.
Liquid whey typically contains about 15-30% solids, which means it adds a good deal of moisture to a TMR. It’s also a rumen-friendly feedstuff in that its lactose is readily fermented and can enhance microbial protein synthesis – as long as it is balanced in the TMR to prevent acidosis. Its sodium and potassium levels also need to be monitored to maintain DCAD balance.
Dairy nutritionist Paul Dyk, MSc, PAS, owner of Forward Dairy Consulting, LLC, Fond du Lac, Wis. and partner with GPS Dairy Consultants, works with several clients who successfully feed fresh whey. “It’s an excellent and economic source of sugar that can replace higher-cost ingredients,” said Dyk.
He shared the two largest challenges with feeding whey are constancy and storage. “There can be a lot of variability in whey, so you definitely want a supply that comes from a single cheese type to ensure a relatively consistent product batch-to-batch,” Dyk advised.
Sweet whey, with a pH of about 6.0-6.7, is a co-product of hard cheeses like cheddar, Swiss, and mozzarella that are produced with a rennet-based coagulant. Acid whey is the result of lactic-acid-based coagulation of products like Greek yogurt, cottage, and ricotta cheese, with a substantially lower pH ranging from about 4.0-5.1, plus higher mineral content.While straight whey is usually not shipped directly to the dairy, whey permeate (less protein) and delactosed permeate (DLP -- some lactose removed) are common liquid products being delivered to dairies.
Dyk said the perishable nature of whey is the other factor that can make it difficult to feed. “A dairy feeding liquid whey will need bulk-tank storage agitate it, and at least 7 days’ worth of storage capacity,” he advised. “The source plant will generally want to move it out as quickly as possible, so you’ve got to be equipped to manage it on your end.Turning the whey over weekly while agitating can keep the product fresh.”
He has seen dairies successfully embrace fresh-whey feeding, generally at about 1-4% total dry matter in the TMR. “Depending on the circumstances, a cheese plant might even be willing to give it away, but there is the investment in trucking and storage that have to be factored in,” Dyk stated.
For lactating rations, dried whey is an alternative that can still make sense in the commodity mix, with advantages in storage, shelf life, and precision in the ration.
Researchers are also looking at alternative strategies to maximize the value of whey. Among the innovative projects in progress are utilizing whey as a fermentation and moisture substrate for silage; using new methods like ion exchange to process and purify condensed whey products; and extracting the water from weigh for drinking and wash water on dairies as an antidote to water scarcity.
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