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Milk Components

Milk components can be very important, a very tell-tale sign of what you are doing or how good the ration is balanced.

First, we need to know what some average fat and protein values are for different breeds of dairy cows.

We will focus on Holsteins because they are the most common breed of dairy cattle. Average Holstein milk should contain about 3.6%, 3.7% fat and about 3.2% protein. When these deviate, or if they are higher, we are really not concerned. But when they get lower than this, when milk fat is depressed, usually it is a problem with the ration. A cow gets the milk fat or the fat she secretes in milk, from two different places. About half of it comes from the acetate and butyrate fermented or produced in the rumen through fermentation. The other half comes from lipids absorbed into the blood from the diet or body fat she is mobilizing.
Low fat tests can be due to two things. One could be an energy shortage. Usually this is about three to five months in milk and, generally, it is characterized by very thin cows and milk fat somewhere between 2.5% and 3%. Protein will also usually be depressed and this means we have an unbalanced ration. Another time we can encounter low milk fat is called milk fat depression at it can actually occur at any stage of lactation. When we look at the cows, they appear to be in good condition. But milk fats are severely depressed. At times can be less than 2.5%. However, milk protein is usually higher and sometimes we have off-feed conditions. Usually if this milk fat depression condition occurs, it is due to too much grain and too little fiber in the diet. These differences are exaggerated a bit if you look at the energy shortage 3% fat, milk fat depression 2.5%. Anything less than 3.5% fat in a Holstein, on an average herd basis, we either have an energy shortage or a milk fat depression problem.

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