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Inheritance of proportionate dwarfism in Angus cattle
M R Latter1, B D H Latter, J F Wilkins
1NSW Agriculture, Agricultural Research and Advisory Station, Grafton, New South Wales. M.Latter@uq.edu.au
Australian Veterinary Journal
|April 25, 2006
Summary
Congenital proportionate dwarfism in Angus cattle is inherited as a dominant autosomal gene with incomplete penetrance. This genetic trait affects cattle breeding and herd management.
Area of Science:
- Veterinary Genetics
- Animal Breeding
- Quantitative Genetics
Background:
- Congenital proportionate dwarfism has been observed in Angus and Angus crossbred cattle.
- The genetic basis of this condition was initially detected in beef herds in New South Wales.
Purpose of the Study:
- To determine the mode of inheritance of congenital proportionate dwarfism in Angus cattle.
- To investigate the genetic mechanisms underlying this heritable trait.
Main Methods:
- Controlled breeding studies were conducted using carrier Angus bulls and unrelated cows of diverse breeds.
- Matings included carrier sires to their unaffected daughters and an unrelated Piedmontese bull to carrier daughters.
- Affected and carrier individuals were analyzed for chromosomal abnormalities.
Main Results:
- Angus dwarfism was successfully reproduced under controlled conditions, confirming its heritability.
- The high incidence of affected offspring (0.38) from matings to unrelated dams is inconsistent with recessive inheritance.
- Both paternal and maternal transmission were observed, ruling out strict imprinting.
- No gross chromosomal abnormalities were detected in affected or carrier individuals.
- Dominant autosomal inheritance with incomplete penetrance was indicated by experimental matings.
Conclusions:
- The mode of inheritance is a single autosomal dominant gene with incomplete penetrance (0.75 +/- 0.12).
- Two genetic models are compatible with the data: a high-frequency unstable mutant or a dominant allele with modifier loci.
- Penetrance may be higher in matings involving carrier daughters of the affected Angus bulls.
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