How's Your Fat Looking?

Energy provider, cell growth supporter, organ protector and vital component for nutrient absorption and hormone production. FAT plays a starring role in animal production and performance. So, it’s likely you think about it all the time. Like the excitement experienced by a child on Christmas morning, you anxiously await the sound of the fat truck pulling into the feed mill, right?

Okay, let’s admit it, fat is not the most exciting element of animal production. There is nothing thrilling, entertaining or “sexy” about fat. As producers, however, we cannot overlook the dramatic impact fat – and its quality – can have on animal health and performance. 

The preservation of fat quality is incredibly important. If you ask feed mill managers and nutritionists about their main concerns regarding fats and oils, most will say quality, variability and value. Did you know that each of these key drivers can be dramatically impacted by the oxidation process?

Oxidation is an irreversible process where fatty acids are attacked by free radicals and oxygen is absorbed. This process results in conversion of fatty acids into harmful byproducts, including peroxides and aldehydes. These toxic contaminants in fat, when fed to animals, may lead to internal oxidative stress, negative gut health implications, reduced performance and immunity challenges for the animal.

Variability in the Market

Understanding the quality of incoming fat is the first step in effective fat management. Oxidation and its effects are irreparable, so it is important to purchase high-quality fat and to maintain that quality. Kemin offers customers the ability to analyze their fat and oil samples for oxidative parameters. This analysis provides an estimation of both the current degree of oxidation and the potential for future oxidation – ultimately, a way to watch out for your bottom line.

Over the years, large variability in oxidative parameters has been noted in animal fats and vegetable oils evaluated by Kemin. In 2017 alone, Kemin Customer Laboratory Services (CLS) analyzed 266 fat and oil samples. Parameters included peroxide value, secondary oxidatives (hexanal + 2, 4-decadienal) and oxidative stability index (OSI). The summary of the testing results for animal fats, vegetable fats and blended fats are below. 

The variability of the current state of oxidation was measured as peroxide value and total secondary oxidatives (Figures 1, 2 & 3). As oxidation takes place, peroxides are formed and consumed. Secondary oxidatives form as peroxides break down and are consumed as oxidation takes place. As a general guideline, fats and oils should contain a peroxide value less than 5 milliequivalents per kilogram (meq/kg) and a total secondary oxidative value less than 50 parts per million (ppm).1 This is indicated in Figures 1, 2 & 3 by the shaded box.

Figure 1. Peroxide value and total secondary oxidative value for animal fats analyzed by Kemin CLS from January to December 2017 (n=84).2

Figure 2. Peroxide value and total secondary oxidative value for vegetable oils analyzed by Kemin CLS from January to December 2017 (n=143).2

Figure 3. Peroxide value and total secondary oxidative value for blended fats analyzed by Kemin CLS from January to December 2017 (n=39).2

Good Quality…But is it Stable?

Outside of the initial quality of the fat or oil, producers must also consider stability. Depending on how stable a fat is, it may take very little exposure to pro-oxidants like oxygen, heat, light, metal ions and enzymes to quickly degrade quality. The 266 samples above were also tested by Kemin CLS for their potential for oxidation (stability) using OSI (Figures 4, 5 & 6). A longer OSI time represents a delay in onset of oxidation and can therefore be interpreted to represent a more stable product.

Figure 4. Number of samples initiating oxidation at different times, analyzed by oxidative stability index (OSI) at 100°C (n=72).2

Figure 5. Number of samples initiating oxidation at different times, analyzed by oxidative stability index (OSI) at 100°C (n=119).2

Figure 6. Number of samples initiating oxidation at different times, analyzed by oxidative stability index (OSI) at 100°C (n=38).2

As you can see, samples of animal fats, vegetable oils and blended fats tested by Kemin CLS had a large variability in both current oxidative status – quality – and future potential for oxidation – stability. So, what can be done to help? An antioxidant may be used to increase the stability of fats and oils prone to oxidation.



1Verleyen, T. 2010. Oxidation key issue in use of oils and fats for feed.

2Kemin Internal Document, 18-00054.

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