Genetic aspects of greasy wool colour assessments in Merino sheep

Author: Daniel J. Brown

Article Type: General Articles

This is an article written for the International Journal of Sheep and Wool Science by Daniel J. Brown

Extracts from report

Wool colour is an important determinant of wool price, especially in fine and superfine Merinos. While objective measurement is not routinely available on farm many Merino breeders subjectively score sheep on greasy wool colour on farm for selection purposes. This study examines subjective greasy wool colour scores from an industry data set. Wool colour scores ranged from 1 to 5, with a score of 1 being superior (whiter) to a score of 5.

Conclusion

Subjectively assessed greasy wool colour is moderately heritable and moderately repeatable. One measurement in the sheep yard or shearing shed would facilitate genetic progress in these traits. The correlations with other important traits are such that progress in all traits is possible, although small unfavourable genetic correlations exist between wool colour scores and body and fleece weight. Further research should also examine the relationships with clean colour plus other non-fleece components of greasy wool (wax, suint) for better understanding of the genetic relationships involved. None of the published studies have examined a full set of these traits. Given that the expression of wool colour is significantly affected by the environment, investigation of possible genotype by environment interactions is desirable prior to implementing into the national genetic evaluation. To facilitate this research and the incorporation of these traits in an across flock genetic evaluation a simple standardised measurement technique is required. With appropriate scoring standards and training in place a subjective score from 1 to 5 as used in this study appears adequate. Such standards already exist from sire evaluation sites and could be used by the wider industry.