Hello
There are different types of whey: liquid and dried whey.The retention of protein level plays an important role to the quality during the manufacturing process and is counting as a feedstuff. Sweet whey is less stable than liquid whey during storage. It will lose up to 40% of its nutritional value if stored longer than 24 hours. That�s why liquid whey has a lower nutritional quality than sweet whey. In my country there are many pig units, trying to avoid the high production costs, feeding the liquid whey as a supplemental protein in the diet of gestation sows. Whey powder is a dried whey considering as a by-product of cheese manufacturing and a kilogram contains about the same amount of nutrients as 14 kg of liquid whey. Dried whey is usually added to diets of weaning pigs as a source of milk protein. The addition levels is 10% or more in the complete rations of piglets. In the photo, brownish color indicates the caramelization through an excessively heated. This lowers the feeding value of the product. Although some good quality whey may have a pinkish or yellowish color from carry-over of the cheese color but the most desirable is white color of the dried whey. Another critical point should take in consideration about the whey quality is the amount of lactose and minerals removed from the dried whey will affect the actual amount of protein. Delactose whey is not recommended for use in baby pig diets. Usually, I recommend skim milk because the level of protein in whey is lower than dried skim milk (12 vs 33 percent). Also, levels of whey higher than 10 percent tend to cause bridging in feeders when the diet is in meal form. However, the biggest benefit of using the whey is usually cheaper source on a per unit of protein basis than dried skim milk. Finally, the main quality factors to look are the content of lactose, protein, ash, color, salt and lysine.
Thanks

Dear Dr. Macromichalis,
I agree with your article, but when talking about whey, main target is to provide lactose, not protein. Of course if whey is overheated or have a bad taste it can provoke feed rejection, but in these moments of high prices of dairy products, I would be more interested in knowing opinions about the interest or not of replacing sweet whey by other lactose sources or other ingredients, such are acid whey, permeate, lactose, etc. I think it is possible without loosing performance.
Dr. Saltykov