Chamberlain, Amy2018-01-312018-01-312017-11-10https://hdl.handle.net/10182/8972The absence of horns in Bos taurus is under the genetic control of the autosomal dominant Polled locus which has been genetically mapped to the centromeric region of cattle chromosome 1 (BTA1). The position of the Polled locus on BTA1 has been identified and candidate causal mutations have been identified. Recently it was demonstrated that there are at least two different alleles at the Polled locus in cattle. For example, a 202-base pair (bp) insertion-deletion (InDel), referred to as P202ID, has been identified in various cattle breeds, including cattle in Scandinavia, Scotland, England, the Channel Islands and France (regions North of the Alpine region). Little is known about breed to breed variation, other than the identification of a Holstein Polled mutation occurring at 932 kb, and that this overlaps with a Simmental Polled locus at 212 kb. Using a polymerase chain reaction – single strand conformational polymorphism (PCR-SSCP) approach, 876 New Zealand (NZ) cattle from five British cattle breeds (South Devon, Belgian Blue, Hereford, Shorthorn and Holstein-Friesian) were sampled, of which 467 were investigated to validate a polled/horned gene test developed by the Lincoln University Gene Marker laboratory. Three PCR-SSCP banding-patterns were identified, and these were typically found in homozygous polled (BB), heterozygous polled (AB) and homozygous horned (AA) cattle. Phenotypic data for polled/horned was available for all 467 cattle, so the accuracy of the gene test was calculated for each breed studied. A high level of confidence can be held when using the gene test in breeds such as the South Devon (100%), Shorthorn (100%) and Belgian Blue (96.5%), but a lower accuracy was observed with Hereford cattle (73.5%). The Holstein-Friesian cattle that were typed were true to phenotype (100%), but the result is less reliable as the sample size was small and no polled Holstein-Friesians were typed. Overall these results suggest that the gene test has the ability to identify polled and horned genotypes in South Devon, Belgian Blue and Shorthorn cattle, but it requires further refinement for Hereford and Holstein-Friesian.enphenotypegenotypehomozygousheterozygousHerefordSouth DevonBelgian blueShorthornHolstein-Friesianpolled locuspolled cattlehorned cattleBos taurusPCR-SSCPDissertationANZSRC::060499 Genetics not elsewhere classifiedANZSRC::0702 Animal ProductionQ112933415