Variation of mean fibre diameter across mohair fleeces: Implications for within flock animal selection, genetic selection, fleece classing and objective sale lot building

Abstract

The present work was conducted to determine how the average mean fibre diameter (MFD) differences between nine sampling sites vary between sex and flock, to identify differences in MFD variability between sampling sites as a result of between animal and between sire variability and to determine MFD correlations between sampling sites in between animal and between sire variability. Australian Angoras ( n = 300) from two herds in southern Australia were sampled at 12 and 18 months of age at nine sites (mid side, belly, brisket, hind flank, hip, hock, mid back, neck, shoulder). Staples were taken prior to shearing at skin level. For each shearing, differences in MFD between sampling sites, how these differences were affected by property, sex, and sire, and the covariance between sites for sire and individual animal effects were investigated by restricted maximum likelihood (REML) analyses. The median mid side MFD at 12 months of age was Property 1 does 21.9 μm; Property 1 wethers 22.0 μm; Property 2 does 26.6 μm; Property 2 wethers 25.3 μm. The median mid side MFD at 18 months of age was Property 1 does 27.8 μm; Property 1 wethers 27.5 μm. It is concluded that the hip and mid back sites can be recommended for within flock selection (culling) due to their low sampling variability and ease of location. While genetic selection at any central/upper sampling site should be effective for bringing down the average MFD, it might be unwise to exclusively use any one particular site all of the time. For sale, the brisket fibre needs to be placed into a fibre diameter line two grades coarser than the main body of the fleece. On some properties the neck fibre should be placed into a fibre diameter line one grade coarser than the main body of the fleece. The building of mohair sale lots based on tests from the mid side site or any other sampling site should enable segregation of mohair into lots of different commercial value. However, property specific site differences in the distribution of MFD around the fleece need to be accounted for when creating lots to meet a specified MFD.