Quality of milk

By the quality of milk we mean the amount protein and fat in milk..

How the feeding affects the milk quality

The farmers said that the roughage is the basis in input of energy and nutrients, and normally it covers the energy demand. In the biggest part of the lactation, the yield is so big that you have to use concentrate in addition to cover the need for energy, protein, vitamins and minerals. To produce milk of good quality, it is essential that silage is good.

A farmer: "The quality of silage is very important for me, because my milk is used for making cheese".

Wrong fermentation can give wrong taste in milk. Good and right feeding is important so milk should have a right content of fat and protein. Silage has a huge meaning for this. 

Roughage, especially roughage of less good quality, could be very filling. Huge amounts of it can therefore in some cases confine the absorption of energy and nutrients to a high productive dairy cow. Too little roughage however, will affect the normal rumen function. This will affect  milk yield and will reduce the fat percent in milk. Farmers think that feed rations with roughage that contains 35-40% dry matter, gives the highest daily milk yield and normal fat percentage in milk.  A bigger part of roughage will lead to reduced milk yield, and less den 50% roughage will lead to reduced fat percent.

Milk protein

Low level of milk protein can be caused by lack of energy or protein in feeding. If there is not enough energy compared to protein, a cow isn't able to use protein either. A Dutch farmer explained that a rumen should get fast enough energy (starch and sugar) inable to use all of the fast protein. A cow should also get enough slow energy (NDF) so that a cow doesn’t have to start using protein for energy later on. NDF also improves a function of a rumen. A Finnish farmer we met told that their cows used to get a high amount of protein. Once they reduced the amount of protein in feeding protein content in milk got higher even though milk production stayed the same.

The feeding should also contain enough protein. The nitrogen efficiency can be improved with a good balance in feeding and increasing the amount of sustainable protein. The amount of sustainable protein is quite small but  farmers told us that they use for example soya, turnip rape and leguminous plants for more slow protein. Bigger portion of protein in concentrates is more sustainable than in grass silage.

If the protein level is too low, you should check if the quality of silage corresponds to the one in the feeding plan, feed cows more energy or increase the amount of concentrated feed.

Different volatile fatty acids (VFA), the decay products of carbohydrates in a rumen, affect the composition of milk in different ways. One of the farmers we met in Holland told that a failed preservation of silage can cause higher amounts of undesirable VFA.

Cow starts to use protein for glucose (blood sugar) production if she doesn’t get enough VFA named propionic acid.  This reduces the production of milk protein. A farmer we met in the Netherlands fed his cows commercial product with propionic acid for forty days after the calving.

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Page updated 16.5.2006