Genetic evaluation of fiber length and fiber diameter from Inner Mongolia White Cashmere goats at different ages

The purpose of this study was to estimate the genetic parameters for fiber length (FL) and fiber diameter (FD) in Inner Mongolia White Cashmere goats (IMCGs) across age groups to determine whether genetic improvement of these fleece traits can be attained by early selection. Data on FL and FD were collected for analysis from 2008 to 2012 on IMCGs at the ages of 1–5 years. The 6851 repeat records of 3251 Inner Mongolia Cashmere goats were analyzed. These goats were descendants of 104 sires and 2172 dams. Genetic parameters for FL and FD in IMCGs from 1 to 5 years old were determined using the average Information Restricted Maximum Likelihood (AIREML) method in a multivariate animal model. Estimates of direct additive heritability for each fleece trait were significant across all age groups. The values were 0.19, 0.34, 0.21, 0.23 and 0.18 for FL, and 0.40, 0.39, 0.29, 0.38 and 0.29 for FD from 1 to 5 years old, respectively. The genetic correlation coefficients between FL and FD at each age ranged from 0.12 to 0.38, which were low to moderate. However, the genetic correlations for FL or FD were positive and high for all pairwise age comparisons, ranging from 0.75 to 0.99, and most values for a given trait between any two age classes exceeded 0.85. The high genetic correlations between yearlings and adults for each fleece trait inferred that selecting stocks at earlier ages may lead to genetic progress and improved fiber quality of IMCGs at later ages.