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title: "2.5.1 Example of a dominant allele in cattle: polled (2024)"
canonical: "https://wiki.groenkennisnet.nl/space/TAB/287605215/2.5.1%20Example%20of%20a%20dominant%20allele%20in%20cattle%3A%20polled%20(2024)"
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In loose housing systems for cattle, the horns of the animals can give rise to serious injuries when animals are fighting. Therefore calves are dehorned when they are some weeks old. But the method is under debate from an animal welfare point of view. In some breeds the animals are polled, they do not have horns. Through crossbreeding the allele for polled is introduced e.g. in the Holstein Friesian population. This allele is dominant, which means that one polled allele is sufficient te be polled. Heterozygous carriers get offspring from which 50 per cent is polled and the calves of homozygous carriers are all polled. It is illustrated in this figure:

![image](media://5a5b260c-a0cd-42e3-bac8-a431a85c40f3)