Inbreeding and its effects on fleece traits of Inner Mongolia cashmere goats

• Linear and quadratic effects of inbreeding on fleece characteristics were studied.
• The average inbreeding coefficient for the whole population was 4.01%.
• Inbreeding results in a slightly curvilinear depression on cashmere weight and fiber length.
• Inbreeding decreases fiber diameter.
• Inbreeding appeared not importantly affect the estimation of genetic parameters and breeding values for the fleece characteristics.

The objective of the present study was to evaluate the level of inbreeding and its effects on fleece traits in Inner Mongolia cashmere goats. Data of 36,901 records for 23 year (1990–2012), collected from the breeding flock of Inner Mongolia cashmere goats maintained at the Arbas stock farm, were used in the analyses. The traits studied were cashmere weight (CW), fiber length (FL), and fiber diameter (FD). The average inbreeding coefficient for the whole population was 4.01%, ranging from 0 to 35.94%. The mean rate of inbreeding was 0.32% per year for all animals. To investigate the effect of inbreeding on phenotypic values, genetic parameters and estimated breeding values, two different models including no measure of inbreeding and individual inbreeding coefficients Fi (linear and quadratic) were take into account. The results suggest that both cashmere weight and fiber length increased at low levels of inbreeding, but decreased when levels of inbreeding were higher than 12.5% and 4.4%, respectively, while FD became thinner with any increase of Fi. Moreover, the estimation of genetic parameters and breeding values for the studied characteristics was essentially unaffected by inclusion of Fi in the model.