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Updated coding for Polled animals

 Polled cow imageRecently Holstein Australia’s Board moved to revise the way Polled animals are identified within the Australian Holstein herdbook.

With most AI sires and high ranking North American females being identified using the system used by Holstein USA, Holstein Australia (HA) has adopted the same system in order to keep things as simple as possible for breeders. Please remember animals with the World Holstein (WHFF) codes may still be seen from time to time.

The trait of being polled in dairy cattle is in fact dominant meaning that an animal only needs to get one polled gene from its parents. This is referred to as heterozygous. Animals with two copies of the polled gene are referred to as true polled or homozygous.

What this means is that for an animal to be polled it only needs to receive a copy from one parent. Animals who have one or both parents as true polled (PP) will always be polled.

The diagram below (sourced from dairybullsonline.com) shows the probabilities of polled and horned calves from each potential mating. Horned animals receive the horn gene from both parents.

Polled Image 

(Source: dairybullsonline.com)

The table below shows three distinct groups of animals that exist within the population.

Polled Table

About the US and HA codes

PO (Polled Observed) means that the breeder has observed that the calf is polled but no genetic testing has been done to confirm this. Breeders will be able to accurately identify calves that are born polled and to help maintain the integrity of the PO status HA will fully subsidise the cost of testing for 1 in 50 calves that breeders identify this way.

PC (Polled Confirmed) means animals that have been DNA tested and confirmed as having one polled gene.

PP (the two P’s Indicating two polled genes) means animals that have been DNA tested and confirmed as having two polled genes.

PF (Polled Free) is for animals with polled parents but is either observed by the breeder as having horns or identified through DNA testing.

Conclusion

This is an exciting time for polled breeding in the Holstein population as the quality and quantity of both true polled males and females increases giving breeders the opportunity to reduce or even remove the need to dehorn from their operation without compromising overall genetic merit.