Influence of feed ingredients upon the prediction of protein in animal feed‐mixes by near‐infrared reflectance spectroscopy

Mixed feeds are composed of a wide variety of constituents incorporated to a basic grain formulation. The composition varies depending on daily price fluctuations in commodities. The components most frequently encountered in the feed industry include the cereals, wheat, barley, maize and oats. Protein concentrates include soya bean and rapeseed meals, meatmeal and fishmeal. Roughage is provided by dried grasses and other forage such as lucerne (alfalfa). Other additives are present in the form of vitamin and mineral supplements and antibiotics. Due to differences in mean particle size, particle size distribution and bulk density the slopes of instrument response to composition show significant differences between commodities. The influence of addition of various commodities to basic grain calibrations is illustrated for wheat, barley and maize calibrations. Successful application of near infrared reflectance spectroscopy technology to the analysis of mixed feeds for protein has been achieved using a Neotec Model 41 GQA, by preparing separate calibrations for cattle feeds (with and without urea), pig and poultry feeds.