I have just finished a chapter on lactose for my forthcoming book. At the same time, I was talking with a feed manufacturer in Canada regarding the maximum levels of lactose in piglet diets. This combination of activities reminded me that lactose remains an inconclusive subject for most nutrition professionals.
We know since the 1950s that piglets thrive when dairy products, such as whey and skim milk, are added in simple corn and soybean meal diets. Since then, we have developed more complex diets with sophisticated protein sources, immunoglobulins and a plethora of additives. In addition, in many parts of the world, growth-promoting antibiotics have been withdrawn. All these have created some confusion.
First, some believe that piglets do not require lactose when offered otherwise complex diets. This is not correct. Research conducted at Ohio State University from Dr. Mahan’s laboratory provided some pioneering work on lactose, demonstrating that piglets benefit from lactose irrespective of diet complexity. Perhaps under commercial conditions we can get by with less lactose, but piglets still require it.
Second, some professionals have reduced or removed lactose when diets were first deprived from growth-promoting antibiotics. Lactose is a natural laxative, and, as such, it promotes the appearance of soft fecal material. Not to be confused with pathogenic diarrheas, but nevertheless disturbing when antibiotics were first banned. Nowadays, however, antibiotic replacements and feed formulation changes have reduced or eliminated the risk of pathogenic diarrheas. As such, it is alright to bring lactose levels to higher levels so as not to deprive piglets from a valuable nutrient.
When it comes to lactose, the more the better.
In brief, when it comes to lactose, the more the better. This is the golden rule, only to be violated by feed cost constrains. As for the minimum, there is no single recommendation. As lactose levels drop, feed intake is reduced, with all known consequences on animal gut health. So, lactose is a good investment. Luckily, there are viable alternative sugars, so lactose equivalents can be used in areas that do not produce dairy products, such as in China and other countries.