Test your feed. You have heard it over and over again. But do you do it enough? To some degree it is the results of the report that can indicate how often, or not, you should sample your feed.
NIR verses Wet Chemistry analysis
Sample request forms require you to indicate what analysis you would like to have done. Both wet chemistry and Near Infrared Spectroscopy (NIR) are methods commonly used. Wet chemistry measures the nutritional value using heat and chemicals to break down the forage. For example, NDF is the fiber portion that is not broken down when boiled in a neutral pH solution. This is weighed prior to and following the process and difference is calculated. Although accurate, it is time consuming and not as cost-effective as using NIR.
NIR estimates the nutritional value of the feed using light reflection rather than chemistry to identify and measure amounts of compounds in a sample. The reflectance values are entered into calibration equations which estimate nutrient values. The equations are based on studies which compare split samples for wet chemistry with NIR reflectance. This provides fast, reproducible and cost- effective results with minimal sample preparation by the laboratory providing the service, and allows for timely return of analytical results for the customer. However, if your feed was grown under conditions that are significantly different from those in the calibration set, the accuracy of NIR estimates may decrease
Lately, a new term ‘aNDFom’ has been thrown around in terms of neutral detergent fibre (NDF) evaluations. It varies from NDF in that it is free of ash, which makes it on an ‘organic matter basis’. Some laboratories may be giving you aNDFom values, whereas other laboratories still indicate NDF values. An ashing furnace is used to heat samples to extreme temperatures, leaving a residue of ash, which contains the minerals. This is then weighed and subtracted from the NDF portion, giving the ‘ash-free’ NDF, or aNDFom. Why does this matter? Well, when the NDF is determined, residues of ash are often perceived as part of the NDF value. The variability between NDF and aNDFom varies, as some may have higher ash content due to splashing of soil on leaves due to rainwater, areas prone to flooding, or soil picked up during harvest. This extra step to obtain aNDFom may delay results, but can be valuable to know when evaluating the feed.
Each phase of growth, harvest, storage, or feed-out of a feed involves a quality change, and you have the opportunity to obtain its nutritional value as you see fit. However, to get the most out of your feed, have your feed tested on a regular basis. A simple analysis can go a long way in increasing your bottom line.
By: Anita Heeg, Feed Ingredients and By Products Specialist/OMAFRA