Phenotypic and genetic parameters of fleece traits and live weight in South Australian Angora goats

Abstract

Heritability and phenotypic correlations for traits of Angora buck and doe yearlings (mean age 13 months) were derived from 572 half-sib records of 30 sires. Estimates of heritability ranged from 0 for percentage of medullated fibres (MF) to 0.45 for greasy fleece weight (GFW). Oven dry yield (ODY) was not very heritable (0.02), live weight (LW), staple length (SL) and fibre diameter (FD) lowly heritable (0.13, 0.13 and 0.14, respectively), while face cover score (FC), kemp score (K) and clean fleece weight (CFW) had moderate to high heritabilities (0.24, 0.36 and 0.38, respectively). Most phenotypic correlations among different fleece traits and with live weight were positive and significant. GFW was strongly correlated with CFW (0.99), whereas GFW and CFW were moderately correlated with LW, FD and SL. Correlations of FD with LW, SL, ODY and MF were positive with values of 0.23, 0.28, 0.30 and 0.39, respectively. Heritability estimates were obtained for production traits of does ranging in mean age from 13 to 73 months. Estimates were similar to those obtained for yearling bucks and does, except for MF, which was greater than 0 (0.39). Repeatability values for the same production traits of does were also estimated, being moderate (0.39 to 0.45) for GFW, CFW and MF, low (0.18 to 0.30) for FD, K, FC and LW and very low (0.03 to 0.08) for ODY and SL. The heritability estimates suggest that GFW and CFW would respond effectively to mass selection at yearling age, but that genetic responses to selection in FD, SL and LW would be smaller. Selection against medullated fibres in the fleece (at ages greater than yearling) and face cover on the animal should also result in genetic improvements in these traits.