Feed nutritionists may be patient people, but never when it comes to waiting for amino acid measurements for their next diet formulation. Rapid analysis with near infrared (NIR) offers a fast option for amino acid testing that can be just as reliable as reference analysis in the laboratory. Animal nutritionist Dr Robert Payne, of amino acid supplier Evonik, explains.
by Richard Mills
Evonik produces amino acids for feed and has over 50 years experience of analysing amino acids. Today they test around 15,000 samples a year. And while wet chemistry reference methods remain the gold standard, rapid tests with NIR are increasingly important in delivering timely results to customers to help in the creation of the best possible diets.
In 1995, Evonik launched a service for testing amino acids based on NIR. Called AMINONIR®, it took off and quickly expanded beyond the walls of the Evonik laboratory to include the supply of calibrations for customers’ own NIR instruments. The instruments a
re connected in a network, with the Evonik laboratory at the hub. The network is growing constantly and now includes around 360 NIR instruments located in feed mills and analytic laboratories around the world.
The first calibrations were released in 1996 and today a wide range of tests cover 80% of feedstuffs in use. One of the oldest is the 16-year-old soybean meal calibration, which is based on over 800 samples. “The growth in the use of the calibrations has been particularly strong in recent years,” says Payne. “We are seeing an almost ubiquitous acceptance of NIR for analysis of amino acids and recognition of the quality of our calibrations.”
Reference data for samples used in building the initial calibration for a particular raw material.
NIR equipment and calibration for amino acid testing
Payne describes how NIR instruments used for amino acid analysis need a broad spectral range, particularly in the upper range. “We point out to our customers that not all systems are suitable, even though the price of some may be attractive,” he says. “What is interesting is that some customers start getting into NIR because of the need to test amino acids, and then find out about the many other things NIR can do for them, which is a great success.”
Calibration spectra for a particular raw material. The ability of an instrument to measure in the upper wavelength range is crucial for amino acid analysis.
A suitable instrument is one thing, but the even the best hardware is useless without the right calibration – “the backbone of NIR,” as Payne calls it. The calibration data is founded on a solid platform of reference testing at the Evonik wet chemistry laboratory, with at least 50 samples required for a calibration. “Any supplier of NIR calibrations for amino acids should be able to supply statistics showing that they are backed by good, solid wet chemistry tests,” says Payne. “These must cover a wide range of sample types and origins from around the world. That way you get all the variables – the good, the bad and the ugly. The calibration is then tested against independent samples. As we see samples that don’t fit, we start to revise the calibration. Of course, we want the calibration to be as strong as possible, so this revision is an ongoing process.”
Even calibrations that include samples from around the world, such as the 16-year-old soybean meal calibration, can be improved, and it has become something of a sport for laboratory staff to find occasional outliers that will make calibrations stronger.
The number of wet chemistry samples required for an NIR calibration varies depending on the application. For example, poultry by-products have a lot of variation and need more samples. Statistics show a very strong correlation between wet chemistry and NIR, with most amino acid tests within 2%. For certain amino acids that are difficult to measure with wet chemistry, the variation is a little higher.
Correlation between wet chemistry and NIR.
The perfect feed formulation
Given that the chemical analysis foundation is in place, Payne is confident of the ability of NIR to make a significant difference in diet formulation. “Virtually real-time information takes you a step closer to being able to create that perfect formulation,” he says. “Feed constitutes 50 – 60% of costs in meat production. Managing that aspect is so important for the entire industry, and NIR is critical for success.”
All essential amino acids in feed ingredients can be measured for around 80% of all feedstuffs.
While Evonik has calibrations for all essential amino acids in the majority of feedstuffs, there is still much work to be done. Just one area Evonik islooking into is a measurement for the effect of heat damage on amino acids. A simple example is the reaction of sugars with amino acids that occurs when a piece of bread is toasted. The reaction gives a nice crisp coating, but also reduces the nutrient content of the bread. The effect of heat in the feed production processes is thus of great interest to feed millers.
According to Payne, there are few technical limitations when it comes to achieving even more with NIR. The main frontier lies in the all-important data collection. “In terms of limits, NIR has virtually none, as long as you have a good calibration,” he concludes.
AMINONIR from Evonik Industries
AMINONIR® is a Near Infrared Reflectance Spectroscopy (NIRS) service tool for predicting the crude protein and amino acid content of the most important raw materials.
The service includes the supply of calibrations for an existing NIR machine at a customer’s site. Provided that the equipment meets the Evonik’s standard or higher, Evonik applies its standardisation technique to the local system, which allows the customer to get amino acid predictions within an hour.