Meet the milk fatty acid groups
Jay Giesy, Technical Service Specialist, [email protected]
We now have the ability to routinely evaluate the profile of butterfat as an indication of how it’s being made by the cow. With milk fat analysis, we can assess how well the rumen is functioning and gauge what impact overall management is having on rumen conditions. This can be especially useful when butterfat numbers are less than ideal, or when dealing with milk fat depression.
Milk fat analysis essentially breaks down the butterfat number into key groups of milk fatty acids: de novo, preformed and mixed.
- De novo fatty acids (short chain) are made in the mammary gland then secreted in milk fat.
- Preformed fatty acids (long chain) come from the diet or are mobilized from body stores.
- Mixed fatty acids (medium chain) can be made in the udder or come from the diet.
The milk fat analysis numbers help us understand two things:
- How the rumen bacteria are fermenting the carbohydrates that provide volatile fatty acids (VFA’s) as precursors to make milk fat.
- How dietary fats in the ration are handled in the rumen by rumen microbes.
To understand this interaction better, it’s helpful to review how the rumen reacts to fat. Rumen bugs don't like unsaturated fat, so they try to convert them to saturated fat through a process called rumen biohydrogenation. Under normal conditions, this conversion process follows a preferred “yellow brick road” of sorts. However, when rumen conditions are altered, rumen bugs can take unsaturated fats down ‘a dark path’ producing trans-fat intermediates. As little as 2 to 4 grams of these trans fats can limit a cow’s ability to make de-novo (short chain) fatty acids in the udder – reducing bulk tank butterfat by 0.5% units (e.g. 3.7% to 3.2%).
Milking the Analysis for Actionable Metrics
We can leverage the milk fatty acid profile analysis as a helpful management tool. If milk fat percent and de novo fatty acids are both high, we can be confident that diet and management are keeping the rumen on the yellow brick road and all is going well. Oftentimes, we’ll utilize these numbers to troubleshoot a herd that has moderate or low bulk tank milk fat percent. In many cases, de novo fatty acid content will be low when high levels of unsaturated fatty acids are used in the diet and there are challenges with dining experiences. This combination creates a strange paradox in nature; feeding too much of the wrong fat to a cow can cause her to produce less fat in her milk!
A different scenario is one I saw recently where a herd’s butterfat was a lackluster 3.55 percent, but de novo fatty acids were well above the alarm levels. In this instance, cows responded in milk fat percent, to the addition of a protected bypass fat source. Over four weeks, both mixed and preformed fatty acids increased to above the alarm levels and overall fat test rose to 3.85 percent.
Reach out to me and my team at Contact Us - Cargill Dairy Dreams to learn more about milk fatty acid analysis or if you’d like to start testing your herd.