Dairy At Glance
What is a Rumen Bypass Fat?

What is a Rumen Bypass Fat?

Rumen bypass or "protected" fats are processed dry fats created for easy handling and mixing in animal feeds. Normally all dry fats have high melting points, making them insoluble at rumen body temperature as such, dry fats are not as much "protected" as completely insoluble in the rumen such that they have little impact on rumen fermentation.

 Just after calving there is a reduced feed intake in the cows. While there is increasd energy and protein requirements to sustain milk production. This deficiency often results in a mobilisation of body condition during the early stage of lactation. This negative energy balance phenomenon is inevitable in most dairy herds, which can lead to critical situations like;

(1) A decline in milk production,
(2) Fertility problems and
(3) Increased risk of metabolic illness - particularly ketosis.

Most dairy farmers are also well aware that any improvements they can make in providing extra energy for milk production pre-peak will pay dividends in production terms throughout the lactation. The logical solution is to provide an energy boost. The most efficient way to achieve this is to increase the energy density of the daily ration available to the cow and using a by-pass fat is one way to do so, without the worry of complications with acidosis. However, not all by-pass fat options are equal.


By-Pass Fat is the most energy dense nutrient available; however, fats with low melting points are already liquid in the rumen and can depress rumen fibre digestion and affect intake as well as reducing the absorption of magnesium and calcium. The deleterious effects of fats on rumen activity can be overcome with the use of by-pass fats. By-pass fats do not interfere with rumen function because they have a higher melting point enabling fat particles to bypass the rumen unaffected and to be absorbed in the small intestine.

As on date, there are only three methods of producing dry fats for animal feeds.  One acceptable method for producing a bypass fat is to hydrolyze the fatty acids from tallow, partially hydrogenate them, and then prill them in a spray-chilling tower.

The most widely used and effective method for producing a rumen bypass fat is to react vegetable fatty acids with calcium oxide to form insoluble calcium soaps. Within the feed industry, these calcium soaps, or salts, appear on feed labels as "calcium salts of long chain fatty acids." Fatty acids distilled from palm oil processing are most commonly used to make calcium salts, because these fatty acids are produced in the greatest quantity worldwide. By far, calcium salts of palm fatty acids (PFA) are the highest quality and best understood bypass fat for dairy cattle.

Because large amounts of dietary fat will eventually reduce feed intake of any animal species, feeding guidelines for feeding bypass fats are generally in the range of 1 to 2 lb per cow daily. Performance goals and ration cost will generally be the dominant factors in determining how much bypass fat to feed.

Akshay Sadana

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