The Science Behind Bypass Fats in Dairy Farming

Providing the right nutrition is absolutely crucial for maximizing milk production and keeping dairy cows healthy. While grains and forages supply important energy, fiber, and nutrients, supplementing with fats can offer a real production advantage. But not just any old fat will do; that’s where specialized bypass fats come in. 

What Makes a Fat a “Bypass” Fat?

The word bypass refers to these fats’ unique ability to avoid being completely broken down by microbes in the cow’s rumen (the first stomach compartment). Instead of being fully degraded there, a significant portion of bypass fats are able to travel on and get absorbed further down the digestive tract.

This is an important distinction from regular fats and oils which tend to be almost entirely utilized as energy by rumen microbes in a process called bio-hydrogenation. Bypassing this extensive rumen degradation means more of the fatty acids remain intact to provide nutritional benefits directly to the cow’s own tissues.

Different Types & Techniques

There are a few major ways fats can be rendered relatively inert and “bypass” the rumen fermentation process:

Physical Forming

Creating an inert, indigestible outer coating or matrix physically protects the inner fatty acids from rumen bugs until reaching the small intestine.

Common examples: Calcium salts/soaps of fatty acids, hydrogenated fats, or oils.

Chemical Alteration  

Changing the fat’s chemical structure via hydrogenation or other processes renders it less susceptible to breakdown by rumen microbes.

Common examples: Prilled fatty acids, hydrogenated triglycerides.

For any bypass fat source, minimizing its breakdown in the rumen while maximizing its digestibility later on in the small intestine is the key goal. Sophisticated manufacturing techniques allow this bypass capability to be achieved.

A Concentrated Energy Source

According to the experts over at Energy Feeds International, the primary benefit of feeding bypass fats is their ability to safely increase the energy density of a dairy cow’s diet. Since they are not degraded and used as fuel by rumen microbes first, more of their caloric payload gets absorbed and utilized as metabolizable energy by the cow itself.

With the extremely high energy demands of producing large volumes of milk daily, this extra energy reservoir helps lactating cows to avoid negative energy balance. It also provides more available nutrients for boosting components like milk fat and protein.

Superior Bioavailability

Not only do bypass fats contribute more net energy than conventional fat sources, but their unique fatty acid profiles often render them more digestible and bioavailable.

Most contain high levels of palmitic and other saturated fatty acids that have a higher intestinal absorption efficiency compared to polyunsaturated fatty acids found in many plant and seed oils. Some are designed to mimic the fatty acid composition of butterfat itself for optimal utilization by the cow.

Finding the Right Fit

Not all bypass fat products are created equal when it comes to their degree of rumen protection, intestinal digestibility, and overall nutritional impact. Calcium salts, hydrogenated products, and prilled fats all have slightly different characteristics.

This means carefully evaluating ration formulation and working with qualified bovine nutritionists is critical. The optimum bypass fat source and inclusion rate depends on many factors like:

  • Specific production goals (e.g., increasing components, repro performance, etc.).
  • Stage of lactation and nutrient requirements.
  • Potential interactions with other dietary ingredients.
  • Cost considerations.

Following recommended guidelines on maximum inclusion thresholds (usually under 2 lbs. per cow per day) is also important to avoid potential downsides like depressing fiber digestibility.


When incorporated thoughtfully alongside high-quality forages, concentrates, protein sources, vitamins, and minerals, bypass fats complete a well-rounded nutrition program designed to fuel your herd for sustained peak productivity.

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