Optimized Genetic Testing for Polledness in Multiple Breeds of Cattle

Area of Science:

• Animal Genetics
• Livestock Breeding
• Quantitative Trait Genetics

Background:

• Dehorning cattle is a common husbandry practice but raises welfare concerns.
• Selective breeding for polledness is hindered by complex genetics, particularly in Bos indicus breeds.
• Existing genetic tests for polledness, including microsatellite (MSAT) and single nucleotide polymorphism (SNP) assays, have limitations in accuracy and breed applicability.

Purpose of the Study:

• To evaluate the accuracy of current poll testing assays in cattle.
• To develop an improved genetic test for predicting horn phenotype early in life.
• To address ambiguous and undetermined genotype results in existing poll gene tests.

Main Methods:

• Investigated 39,943 cattle across multiple breeds to assess poll testing accuracy.
• Compared a standard SNP-based assay with earlier MSAT haplotyping methods.
• Developed and validated an optimized poll gene test utilizing a robust set of 5 SNPs.

Main Results:

• The standard SNP-based test improved upon MSAT but failed to predict genotypes in 9.69% of animals, predominantly those with Bos indicus influence.
• The optimized poll gene test successfully resolved the majority of previously undetermined genotypes.
• The optimized test achieved 99.96% accuracy in predicting genotypes and can determine PC and PF alleles.

Conclusions:

• An optimized 5-SNP genetic test effectively predicts polledness in cattle, overcoming limitations of previous assays.
• This improved genetic testing enhances accuracy for cattle breeds, including those with Bos indicus genetics.
• The optimized test provides reliable early-in-life prediction, supporting selective breeding and animal welfare.