Milk is not just milk. Season, geography, cow breeds and feeding strategies are just some of the factors that influence the ingredients in Danish dairy milk.

In collaboration with a number of Danish dairies, researchers from Aarhus University have analyzed more than 700 milk samples to learn more about exactly how wide the variation is in the composition of Danish dairy milk.

Over a period of two years, samples were taken every month from 15 different dairies' silo tanks throughout Denmark, from Bornholm in the east to Zealand, West, North and South Jutland. In addition to conventional milk, organic and biodynamic milk and a number of other lines adding up to a total of 35 lines of milk sampled.

Groundbreaking study

There has been made several previous studies of cow-level variations in milk constituents, but no large-scale, published studies of milk variation at the silo level in Denmark has been made. Until now.

In the studies, researchers have looked at the milk's protein composition, content of vitamins, minerals, fatty acids, metabolites and a number of more complex milk components. Several of the measured parameters have never before been measured in Danish silo milk, and the project therefore also contributes with completely new knowledge about the ingredients in Danish milk.

"The idea of DanMilk has been to delve into the different ways we produce milk in Denmark. What does that mean for the content and not least the variation in the ingredients in the milk. And what contributes to these variations?" asks Professor Lotte Bach Larsen from the Department of Food Science at Aarhus University, who has been in charge of the project.

She elaborates: "The quality and ingredients are significant factors when it comes to further processing. The ingredients affect the milk's ability to coagulate and become cheese. It also is important for the dairies to know the natural variation in the milk’s composition because some is concentrated or can have influence on the processing," she says.

PhD project

Part of the DanMilk project is a PhD project entitled "Diversification in protein and micronutrient profiles of bovine milk relative to primary management factors," which was written by Natacha Veje Róin. The PhD defense also marked the official end of the DanMilk project.

The PhD project has specifically investigated the variations across production systems.

"One of the things we see most clearly is that the variations are greatest in the organic and biodynamic milk, where conventional milk is more uniform all year round," says Nacha Veje Róin and elaborates:

"For example, we can clearly see that the seasonal variation in the milk components is clearly linked to production form and especially feed."

Conventional milk is more uniform compared to organic and biodynamic milk, where seasonal variations in especially feed have an impact on the composition of ingredients and product quality.

The PhD project has resulted in three scientific articles published in International Dairy Journal and Journal of Dairy Science. In addition to the PhD project, a number of bachelor projects and master theses have also been completed under DanMilk.

More types than ever

The project has provided valuable new knowledge about Danish milk.

"We have mapped almost all the lines that exist in Denmark, and that in itself is groundbreaking. The fact that we have mapped this diversity and what it means for the properties of the milk - and how those properties can change from day to day in some cases," explains Professor Lotte Bach Larsen.

But the composition of the smaller, non-conventional milk types has also been thoroughly studied.

"We have looked at the breadth, but we have also looked at the more special lines to see what diversity there is in Danish milk," she says.

The variations in milk present both opportunities and challenges - namely opportunities for differentiation and challenges with variations in production due to the milk raw material. The different characteristics are particularly interesting to investigate now that supermarket choice is wider than ever before.

More sustainable future

The analyses have shown that biodynamic milk has a higher content of vitamin E, vitamin B2 (riboflavin) and another fatty acid profile compared to conventional milk. On the other hand, the analyses showed that conventional milk has a higher content of lactose, selenium and vitamin B12 compared to organic and biodynamic milk.

In general, what matters most for milk constituents are management, feed and breed. Feed matters most for fatty acid composition and metabolites while cow genetics matter most for protein variation.

The project is also an important step towards better utilization of the whole raw material - and thus a more sustainable milk production in the future. This is especially important in the part of the industry that uses powder-based ingredients, which is used in the production of infant formula, among other things. Here, there are very strict requirements for specifications.

"If you as a producer fall outside the specifications, the end product is discarded, but if you can predict it, you can use the milk for something else and thus create a more sustainable production in the industry," explains the researcher.

A future with feed additives

Although the project is the first of its kind in a Danish context, Professor Lotte Bach Larsen hopes it will not be the last. DanMilk finds its inspiration in a number of large Swedish studies that have been carried out at regular intervals, where it has been possible to follow the development of ingredients.

And this is particularly interesting at the moment, explains the researcher. There are a lot of special things happening in feed supplements for cows in relation to climate adaptation. Therefore, the study can also serve as a kind of baseline measurement.

"Because we don't really know what it means for the milk constituents at the silo level," she says.

Therefore, she hopes that it will be possible to repeat the study in five years to be able to answer what the increasing focus on sustainability means for the ingredients in the milk of the future.