Evaluation of mean fiber diameter measurements by FibreLux micron meter and OFDA2000 in Texas and Intermountain west wool

Objective measurements of wool, specifically mean fiber diameter (MFD), plays an important role in the selection of replacement animals and the marketing of greasy wool. The FibreLux (FL) was designed for field use and will be a cost-effective instrument for producers if it compares favorably to the OFDA2000 on U.S. wool samples. The aim of this study was to compare accuracy and precision of the FL to the OFDA2000 for measurement of mean fiber diameter of U.S. wool. We hypothesized that MFD accuracy of the FL vs. OFDA2000 would be within manufacturer recommended 0.8 μm specifications in U.S. wool samples. Wool from animals originating from two distinct regions was used in this study. Side samples from Montana, Wyoming, and South Dakota (n = 998; 21 flocks) and Texas (n = 883; 11 flocks) were measured on the FL and OFDA2000 at the Montana State University Wool Lab (MSU) and the Texas A&M AgriLife Bill Simms Wool and Mohair Research Lab (AgriLife), respectively. The FL and OFDA2000 were strongly correlated (P < 0.001) at both MSU (r = 0.89) and AgriLife (r = 0.93), yet differed (P < 0.001) between the two laboratories. At MSU the FL measurements were 0.25 μm greater (P < 0.001) than the OFDA2000. The opposite was found at AgriLife, where the FL measurements were 0.21 μm less (P < 0.001) than the OFDA2000. At MSU, the slope of the geometric mean regression coefficient did not differ (P = 0.111) from unity. In contrast, AgriLife underestimated MFD by 0.9 μm for 15 μm fibers and overestimated MFD by 0.7 μm at 25 μm (P < 0.001). Samples coarser than 25 μm indicated that the FL can provide useful measurements above the specified range. Standard error of predictions were 0.94 and 0.67 μm for MSU and AgriLife, respectively. The FL variance components were greater than the OFDA2000, with the greatest source of variation was from multiple staples within the same fleece, and reload error was greater for FL than OFDA2000. We believe the FibreLux will be a useful tool for on farm measuring of MFD in U.S. wools.