The inheritance of fibre traits in a crossbred population of cashmere goats

Genetic parameters were calculated for fibre traits measured on patch samples taken at 5 months of age on a crossbred population of cashmere goats, comprising goats of Scottish feral, Icelandic, Tasmanian, New Zealand and Siberian origin. Within-strain heritabilities,fitting genetic origin as a covariable, were: live weight, 0.71 (s.e. 0.08), fibre diameter, 0.63 (0.07), diameter standard deviation 0.43 (0.08), log (patch cashmere weight), 0.60 (0.06), log(estimated annual cashmere production), 0.51 (0.07), and fibre length, 0.49 (0.15). Including between strain information increased these values to 0.74, 0.68, 0.45, 0.73, 0.67 and 0.57, respectively. Maternal effects for all fibre traits were negligible. Expressions were derived to relate cashmere weight to fibre diameter and length, using functional relationships between these traits. Logarithmic regressions showed cashmere weight to be proportional to diameter(2.7), indicating that selection to reduce fibre diameter will have a disproportionate effect on cashmere weight. Analyses of subsets of the data confirmed this and showed that correlated responses to selection can be accurately predicted by considering the functionally related fibre traits on the log scale.