Tag: "heritability"

  • Pigment, Curvature, and a Caution About the Assumed Heritability of Phenotypic Fleece Character

    People who process alpaca fiber into products are well aware that dark fleece behaves differently than lighter fleece in processing as well as in many final products. Even if the fineness and uniformity of a batch of dark fleeces is identical to that of a batch of white, for instance, the yarns made from those fleeces will be denser (and heavier) at the same gauge and exhibit less memory, making its performance in end products different than yarns made from light fiber. The reason for the difference is that the fibers making up the fleeces at the darker end of the spectrum of alpaca colors have less curvature than those from lighter-colored fleeces of similar fineness and length. The question is, why? The analysis below hints at a possible answer. more »
  • The Inheritance of and Associations Among Some Production Traits in Young Australian Alpacas

    Phenotypic and genetic parameters for young Australian Alpacas are presented and compared with Alpaca reports in the literature, as well as with estimates for South Australian (SA) Merino sheep. The traits studied were greasy and clean fleece weight (GFW and CFW), fibre yield (YLD), mean fibre diameter (FD), coefficient of variation of FD (CVFD), staple length (SL) and live weight (LW). Most mean values fell within those found in the literature, except for YLD, which was greater in our study. YLD, FD, SL and LW were greater than for Merino sheep, whereas the opposite was true for GFW and CFW. The heritability was high (0.37 or greater) for all traits. The estimate for LW fell within the range in the literature, whereas for GFW and SL our values were greater. Relative to those for SA Merino sheep our estimates were greater for GFW, CFW, CVFD and LW, whereas they were lower for the remaining traits, except for SL, which had the same value. Phenotypic correlations from the literature were in broad agreement with ours. Those from SA Merino hoggets, except for some correlations involving YLD and SL, were in remarkable agreement with ours. The practical implications of the findings are discussed. more »
  • Is Fibre Diameter Variation Along the Staple a Good Indirect Selection Criterion for Staple Strength?

    The coefficient of variation of fibre diameter (CVFD) within the mid-side fleece sample is currently used to predict staple strength (SS) in Merino sheep (4.5 year old ewes). CVFD measures fibre diameter variation both between fibres and along wool fibres. It has been suggested that selection to improve staple strength should concentrate on reducing fibre diameter ariation along the staple, rather than CVFD. Our results indicate that measurements of fibre diameter variability along the staple had low heritabilities to moderate (0.01 to 0.20) and a low to moderate (0.15 to -0.43) phenotypic correlation with staple strength. In comparison, CVFD was highly heritable (0.78) and had a moderate (-0.44) phenotypic correlation with S. This suggests that there would be no advantage in using measures of fibre diameter variability along the staple as an indirect selection criterion for SS compared with the information provided by CVFD measured in a mid-side fleece sample. more »

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