Dairy Science Department
BS in Dairy Science
The objective of this experiment was to determine how closely related two different near infrared reflectance spectroscopy machines were in analyzing the components of corn silage and alfalfa hay. Near infrared reflectance spectroscopy (NIRS) is a method of analyzing the composition of forages in a fast and repeatable way by exposing a sample to near infrared light and recording which wavelengths are absorbed and which are not. All of the major components of corn silage and alfalfa hay have known absorption rates of near infrared light. By calculating which wavelengths of light are absorbed and which ones are reflected back, a value can be assigned for how much of each component a feed has. Corn silage and alfalfa hay samples were taken between July 3, 2013 and August 7, 2013. There were a total of 79 corn silage samples taken from 36 dairies. Dairies that had multiple samples taken from them were separated by at least 3 weeks to allow for a new part of the pile to be exposed and tested. There were a total of 76 samples of alfalfa hay that were sampled. These samples came from 25 different dairies. The same lot of hay was never tested twice in this experiment. All samples were tested in the AgriNIR Forage Analyzer first. The same sample was then taken and analyzed by Dairy One Forage Analyzing Laboratory. There was a large difference in the results between the two machines. They had disagreement in their test results and the disagreement varied by component. Several components had a low correlation between the two machines, so the disagreement was not linear. Other components had a high correlation, but they had a large difference in actual values.