Recessive and dominant inheritance patterns associated with synonymous differences in wool fibre curvature and medullation

ABSTRACT

Segregation into lustrous and wild-type birth coats suggested both dominant and recessive inheritance patterns associated with birth coat and subsequently with low wool fibre curvature at lamb and yearling shearing. The hypothesis that these phenotypes also differ in the proportion of medullated fibres (%) was tested here. Progeny expressing dominant segregation of lustre at birth showed significant differences in medullation of lambs wool (P < 0.001), where 42.3% (SEM ± 6.5%) of fibres were medullated in the lustrous phenotype, and 4.8% (± 1.0%) in the wild-type. Medullation at yearling shearing had declined to 19.7% (± 5.3%) and 1.8% (± 0.3%) respectively but the significant difference prevailed (P < 0.001). Progeny expressing recessive segregation of lustre also exhibited more medullation as lambs (54.6% ± 6.0%) with only 9.5% (± 2.6%) in the wild-type (P < 0.001). Again, medullation declined in yearlings but the difference (P < 0.001) between phenotypes remained (22.6 ± 8.2 vs. 4.0 ± 1.7%). For both inheritance patterns medullation increased as fibre diameter increased in lambs wool (P < 0.001), but across the range of fibre diameter observed, more fibres were medullated in those lustrous at birth (P = 0.001).

KEYWORDS:

• Wool bulk
• hairy
• woolly
• crimp
• lustre

Acknowledgements

Hayley Lloyd identified three of the sires found on Lincoln Research farm, and it was her persistence that allowed us to bring these findings to light. We are also very grateful to Alison Waugh who brought to our attention the original lustrous sire carrying the recessive gene and Issi Anderson who bred Razzle and retained him as an entire male.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Ministry of Business, Innovation and Employment [C10X0710].