Genetic and non-genetic variability of OFDA-medullated fibre contents and other fleece traits in the French Angora goats

Within the French selection scheme of Angora goats for mohair production, new criteria for assessment and measurement of medullation were introduced in 1999. An optical fibre distribution analyser (OFDA) has been routinely used for measuring distribution of fibre diameter and medullation content and at the same time, a new method of scoring medullation was defined. The aim of this study was to analyse variability of these new fibre and fleece characteristics in French Angora goats. The dataset was extracted from the on-farm performance recording system and included 1505 records from 1419 animals of both sexes from a total of 36 different farms. OFDA kemp (or coarse medullated fibres) and med (or other medullated fibres) contents increased significantly with age and with large variation among farms and years of production. Heritability estimates of greasy fleece weight (GFW), mean fibre diameter (MFD), CV (coefficient of variation) of fibre diameter, OFDA kemp and OFDA med content were 0.25, 0.51, 0.29, 0.32 and 0.23, respectively but smaller for medullation score (0.14). High favourable genetic correlations were estimated between kemp and med OFDA content (0.70), as well as between kemp score and kemp content (KEM) (−0.70). These results will be used to estimate breeding values of animals and to improve the efficiency of selection against medullated fibres by using OFDA medullation measurements routinely within the genetic improvement programme for Angora goats in France.