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NIRS provides rapid feed-ingredient analysis

Cost of $40,000 can potentially be paid off within six months on a moderate-size beef or hog operation

The technique of Near Infrared Reflectance Spectrometry (NIRS) analysis is set to change the way livestock producers evaluate feed ingredients and have their rations formulated. Because this technology provides a rapid assessment of a wide range of nutritional parameters, such as energy value, dry matter and protein, the economic value of ingredients such as cereals and oilseeds can quickly be calculated. It can even measure the nutrient values of forage and manure.

So what is NIRS and how does it work?

“NIRS is based on light energy from a tungsten bulb reflecting off molecules in the grain or other substrate and the light that is reflected back is measured,” explains Mary Lou Swift, research scientist, feed quality, at Alberta Agriculture and Rural Development, who has worked on NIRS for many years. “It relies on establishing a relationship between the pattern of energy absorption by chemical bonds within the sample and an animal or laboratory bioassay reference method.” She notes that, in most cases, whole grains or other ingredients are used for the analysis.

Swift is working with Dr. Ruurd Zijlstra and Dr. José Landero at the University of Alberta, whose focus has been on developing calibration equations for the DE content of wheat and barley. “Energy is the most costly component of the diet and the digestible energy (DE) in barley may vary by as much as 20 per cent,” notes Zijlstra. “Assessment by bushel weight is inaccurate as it only accounts for 14 per cent of the variation in energy content in barley, while chemical analysis is moderately accurate but is costly and also takes a long time.”

Wheat and barley tests

The group has developed an NIRS calibration model for energy digestibility in wheat and barley, which is unique in North America. “NIRS technology requires reference samples with a wide variance in the component of interest in order to calibrate the instrument,” says Zijlstra. “The reference point for DE is fecal DE or in vitro DE measurement. You have to develop a relationship between the NIRS ‘fingerprint’ and fecal DE by regression analysis, in other words NIRS is not a direct measurement, it’s a secondary method.”

In total 221 barley and 99 wheat samples were selected based on genetic background and physical and chemical characteristics. Digestible energy was measured by feeding the grain to pigs and measuring fecal DE. It was also measured in the laboratory and scanned using an NIRS machine.

“The relationship between the NIRS values and the other measurements is very accurate,” Zijlstra says. “Work will continue in our lab to add sample data to existing calibration models in order to increase their robustness in terms of sample variation.

“For barley, the variation in DE may be from 2,700-3,500 kCals/kg at 90 per cent dry matter, although the majority of samples will be in the range of 2,900-3,400,” Zijlstra says. “Each 100 kCals is worth $10 per tonne.” With higher ingredient prices the value of accurate measurement is high, he stresses. “Not only is it important to know the value of the energy in grain in order to avoid overpaying for it, but also making a wrong assumption about nutritional value has implications for pig performance.”

Lysine-to-energy ratio

In addition, being able to achieve the correct lysine-to-energy ratio in pig diets is very valuable. “If energy is low relative to protein, then excess protein will be broken down, which is inefficient and also increases nitrogen content of the manure,” says Zijlstra. “On the other hand if energy is higher than the value used for formulation, there will be insufficient protein relative to the energy value, resulting in slower growth, which is also costly.”

Ron Gietz, provincial pork specialist with Alberta Agriculture and Rural Development, says that based on the energy value of Alberta barley samples at current market prices, hog producers will frequently be paying up to $17 per tonne too much for some barley loads and $11 per tonne below energy value for others. “The difference from best to worst barley is worth at least $8 per hog and that’s often the difference between profit and loss in this industry.”

With the move to phosphorus-based manure management regulations in Manitoba, the use of NIRS can help to ensure that rations contain the correct level of available P in order to reduce its excretion. NIRS is also being used to measure the nutrients in manure, both to facilitate accurate nutrient application and to minimize environmental impact.

NIRS is not new technology, but in recent years it has become affordable, which has led to more widespread use in the feed industry. Now, with machines costing in the region of $40,000, which can potentially be paid off within six months on a moderate-size beef or hog operation, their use is expanding considerably.

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