Characteristics of Angora rabbit fiber using optical fiber diameter analyzer 1 S. A. Rafat,* H. de Rochambeau,* M. Brims,† R. G. The ´ bault,‡ S. Deretz,‡ M. Bonnet,‡ and D. Allain* 2 *Institut National de la Recherche Agronomique, UR631, Station d’Ame ´lioration Ge ´ne ´tique des Animaux, 31326 Castanet-Tolosan, France; †BSC Electronics Pty Ltd., Ardross 6153, Western Australia; and ‡Institut National de la Recherche Agronomique, UE 969 Ge ´ne ´tique Animale Phane `res, Le Magneraud, 17700 Surge `res, France ABSTRACT: An experiment was conducted to de- scribe the characteristics of Angora rabbit fiber using optical fiber diameter analyzer (OFDA). A total of 349 fleece samples were collected from 60 French Angora rabbits. Recorded measurements of OFDA were as fol- lows: mean fiber diameter, CV of fiber diameter, comfort factor, spinning fineness, mean fiber curvature, SD of fiber curvature, mean opacity of fibers, percentage of medullated fibers, mean fiber diameter along the length, and SD of fiber diameter along the length. Com- fort factor is the percentage of fibers less than or equal to 30 microns. The main effects included in the mixed model were fixed effects of group, harvest season, and age and a random effect of animal. Correlations among total fleece weight, compression, and OFDA measure- ments were calculated. Mean fiber diameter was lower than the fiber diameter along the length. Mean percent- age of medullated fibers was very low and ranged from Key words: Angora, fiber characteristic, rabbit, wool ©2007 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2007. 85:3116–3122 doi:10.2527/jas.2007-0109 INTRODUCTION Because average fiber diameter determines pro- cessing performance and end use of wool, it is one of the most important characteristics that determines market price of wool. More rapid, accurate, and efficient meth- ods of measuring fiber diameter are of considerable in- terest for animal fibers (Qi et al., 1994). Angora rabbits produce fibers called Angora, which belongs to the lux- ury animal fibers category. The projection microscope method for measuring fiber diameter in Angora rabbits has been used in some studies (Rougeot and The ´bault, 1 This work was supported by a studentship to S. A. Rafat from the University of Tabriz, Iran. 2 Corresponding author: daniel.allain@toulouse.inra.fr Received February 19, 2007. Accepted July 3, 2007. 3116 0.1 to 7.3%. The mean comfort factor was 97.5% and ranged from 93.3 to 99.8%. The mean fiber curvature was 40.1 degrees/mm. The major changes in Angora fleece characteristics from 8 to 105 wk of age were an increase in fiber diameter, CV of fiber diameter, mean fiber diameter along the length and curvature, and a decrease in compression and comfort factor. The effect of harvest season was significant on some fiber charac- teristics. Mean fiber diameter and the mean fiber diam- eter along the length had a positive correlation with total fleece weight. The OFDA methodology is a method to evaluate fiber diameter, CV of fiber diameter, and bristle content through measuring of the comfort factor. However, OFDA is not adapted for measuring opacity or size of the medulla, or both, in Angora wool and needs a new definition or a special calibration. The spinning fineness should be redefined and adapted for Angora rabbits. 1983, 1989; Qi et al., 1994; The ´bault and Vrillon, 1994; Olmez and Dellal, 2002; Risam et al., 2005). However, differences among studies were due to the influence of fiber properties. The Angora rabbit fleece is made of different kinds of medullated fibers that have a variable cross-section shape between and along the fiber. A rapid method for measuring cross-section characteristics of the different fiber types of the Angora rabbit fleece has been proposed (Allain and The ´bault, 1996). However, this method is not widely used, because it required a skilled operator and was time-consuming. The optical fiber diameter analyzer (OFDA) is capable of providing an acceptable estimation of fiber characteristics in mohair (Lupton and Pfeiffer, 1998), wool (Baxter et al., 1992; Cottle et al., 1996; Peterson and Gherardhi, 1996; Baxter, 1998; Allain and The ´bault, 2000), and cashmere (Peterson and Gherardhi, 1996; Herrmann and Wortmann, 1997). Allain and The ´bault (2000) showed that OFDA may