Genetic parameter estimation and genome-wide association study of fiber characteristics for cashmere goats in the United States

There are currently no genetic selection tools available to cashmere producers in the United States, presenting an opportunity for improvement of cashmere fiber characteristics through the development and implementation of such tools. Cashmere producers submitted sheared fiber samples to the Texas A&M Bill Sims Wool and Mohair Research Laboratory in San Angelo, Texas for the measurement of mean fiber diameter (MFD), standard deviation of diameter (SDD), coefficient of variation of diameter (CVD), curvature (CURV), standard deviation of curvature (SDCurv), coarse edge micron (CEM), spinning fineness (SpinF), and percentage ≤ 19 µm (Perc_19). Staple length (SL) and greasy fleece weight (FW) were measured by individual producers using a ruler and scale, respectively. Pedigree records were provided by collaborating producers and all goats were genotyped on the Goat GGP 70K BeadChip (Neogen Corp.). Variance components for each trait were estimated using the BLUPF90 suite of programs and a mixed animal model that included significant fixed effects: age at cashmere collection (year), sex, and contemporary group (farm x testing year). Estimated heritabilities for MFD, SDD, CVD, CURV, SDCurv, CEM, SpinF, Perc_19, SL, and FW were 0.49 ± 0.07, 0.27 ± 0.07, 0.29 ± 0.07, 0.48 ± 0.06, 0.38 ± 0.07, 0.36 ± 0.07, 0.45 ± 0.07, 0.50 ± 0.07, 0.48 ± 0.07, and 0.52 ± 0.19, respectively. In general, repeatability of cashmere fiber traits were moderate to high. Both phenotypic and genetic correlations varied between pairs of traits. The genetic correlations MFD had with CVD, SDCURV, SL, and FW were unfavorable and warrant consideration to avoid antagonistic correlated responses to selection. Significant single nucleotide polymorphisms (SNPs) were identified for cashmere fiber characteristics. Several genes located within the QTL region (± 50 kb) of these SNPs have previously been associated with fiber production or related biological processes. These results suggest that cashmere fiber traits are heritable, and genetic improvement of cashmere fiber production is feasible. This study could provide a foundation for the future development of a genetic selection tool for U.S. cashmere producers.