Polledness is a genetic occurrence whereby animals from a mainly horned cattle breed do not develop horns. If left to chance a polled animal would not come along in a horned breed very often. Where horned bulls and cows mate, only one in 20,000 calvings would result in a polled calf. So polling is the process of selective matings between polled animals so as to increase the number of polled animals in a traditionally horned breed.
The polled gene (P) is actually dominant over the horned one (p). So, if a bull has two polled genes (PP), homozygous, then all of its resulting calves will be polled. Also if a bull has one polled and one horned gene (Pp), heterozygous, it will also be polled. However, if it is heterozygous polled (Pp), it will pass either the polled or horned gene on, resulting in half of its calves being horned and half of them being polled.
Scurs
There are additional genes that affect horn-like growths called scurs on an animal’s head. Scurs are incompletely developed horns which are generally loose and movable beneath the skin, not attached to the skull. They range in size from small scab-like growths to occasionally being almost as large as horns. Because the gene for scurs is transmitted separately, it has no effect on the presence or absence of horns. Not all horned cattle carry the gene for scurs and not all polled cattle lack the scur gene. Scurs can cause a lot of confusion for someone who expected the calves of a polled bull to all come completely polled. It is important to remember that scurs are controlled by a different set of genes and can occur on polled bulls.
The gene for scurs is expressed differently from the gene for polledness. The sex of the animal has an effect on how scurs appear. They are more common in bulls than cows. In males, the scur gene is dominant, meaning that if only one of the two genes is for scurs, the bull will be scurred. So it is easy to tell if the bull is carrying the scur gene and eliminate it from the herd.
For cows, however, the scur gene is recessive, meaning that she must possess both genes for scurs in order for the cow to be scurred. If the cow possesses only one scur gene she will not have scurs but has a 50% chance of passing the scur gene on to her calf. This is why you would hear of animals being either ‘smooth polled’ or ‘scurred’.
Benefits
There are obvious benefits from working with polled cattle in terms of less risk of injury as well as stress on the calf and the cost of dehorning. However, there is another benefit that largely goes unnoticed but which is important in today’s world of €uro-Stars.
The ICBF reflects the benefits of polledness in its breeding indexes. Polledness has an economic weighting of €5.95 in the Replacement Index. All animals, apart from Aberdeen Angus (AA), must be genotyped to establish their polledness status before a polledness contribution can be included in their index. All AA animals will be given a polledness contribution depending on the percentage AA in their breed makeup before they are genotyped. Once genotyped and the polledness status can be properly established, AA animals will either receive the homozygous (€5.95) or heterozygous (€2.97) value.
Genotyped homozygous polled animals (all progeny polled) receive the full contribution of €5.95.Genotyped heterozygous polled animals (half of progeny polled) receive half of the contribution of €2.97.All non-genotyped AA animals receive a percentage of the full contribution depending on the percentage AA in their breed makeup. For example, an animal that is 62.5% AA will receive a polledness contribution of €3.72.All genotyped AA animals will either receive the homozygous or heterozygous contribution depending on polled status.In the past, polled cattle were considered to be behind their horned counterparts in terms of quality and performance. However breeding programmes around the world have greatly reduced that gap. Indeed, the number of polled beef and dairy bulls available in Irish AI, although small, is still far greater than it used to be and appears to be growing every year.
AI Bulls
Angus and Hereford have always been the most well known breeds for polledness. However, in recent years the percentage of polled animals is increasing across many different breeds. Outside of Angus and Hereford, a total of 180 polled AI bulls have been used in Ireland to-date. They range across 18 different breeds, with Simmental having the most with 49 polled AI bulls coded to-date. Traditionally breeders would have just brought in a small quantity of semen from particular polled bulls for their own pedigree matings. Now it is becoming more common for AI companies to carry semen of polled bulls from these other breeds as well as standing such bulls in their studs.
Polledness is a genetic occurrence whereby animals from a mainly horned cattle breed do not develop horns. If left to chance a polled animal would not come along in a horned breed very often. Where horned bulls and cows mate, only one in 20,000 calvings would result in a polled calf. So polling is the process of selective matings between polled animals so as to increase the number of polled animals in a traditionally horned breed.
The polled gene (P) is actually dominant over the horned one (p). So, if a bull has two polled genes (PP), homozygous, then all of its resulting calves will be polled. Also if a bull has one polled and one horned gene (Pp), heterozygous, it will also be polled. However, if it is heterozygous polled (Pp), it will pass either the polled or horned gene on, resulting in half of its calves being horned and half of them being polled.
Scurs
There are additional genes that affect horn-like growths called scurs on an animal’s head. Scurs are incompletely developed horns which are generally loose and movable beneath the skin, not attached to the skull. They range in size from small scab-like growths to occasionally being almost as large as horns. Because the gene for scurs is transmitted separately, it has no effect on the presence or absence of horns. Not all horned cattle carry the gene for scurs and not all polled cattle lack the scur gene. Scurs can cause a lot of confusion for someone who expected the calves of a polled bull to all come completely polled. It is important to remember that scurs are controlled by a different set of genes and can occur on polled bulls.
The gene for scurs is expressed differently from the gene for polledness. The sex of the animal has an effect on how scurs appear. They are more common in bulls than cows. In males, the scur gene is dominant, meaning that if only one of the two genes is for scurs, the bull will be scurred. So it is easy to tell if the bull is carrying the scur gene and eliminate it from the herd.
For cows, however, the scur gene is recessive, meaning that she must possess both genes for scurs in order for the cow to be scurred. If the cow possesses only one scur gene she will not have scurs but has a 50% chance of passing the scur gene on to her calf. This is why you would hear of animals being either ‘smooth polled’ or ‘scurred’.
Benefits
There are obvious benefits from working with polled cattle in terms of less risk of injury as well as stress on the calf and the cost of dehorning. However, there is another benefit that largely goes unnoticed but which is important in today’s world of €uro-Stars.
The ICBF reflects the benefits of polledness in its breeding indexes. Polledness has an economic weighting of €5.95 in the Replacement Index. All animals, apart from Aberdeen Angus (AA), must be genotyped to establish their polledness status before a polledness contribution can be included in their index. All AA animals will be given a polledness contribution depending on the percentage AA in their breed makeup before they are genotyped. Once genotyped and the polledness status can be properly established, AA animals will either receive the homozygous (€5.95) or heterozygous (€2.97) value.
Genotyped homozygous polled animals (all progeny polled) receive the full contribution of €5.95.Genotyped heterozygous polled animals (half of progeny polled) receive half of the contribution of €2.97.All non-genotyped AA animals receive a percentage of the full contribution depending on the percentage AA in their breed makeup. For example, an animal that is 62.5% AA will receive a polledness contribution of €3.72.All genotyped AA animals will either receive the homozygous or heterozygous contribution depending on polled status.In the past, polled cattle were considered to be behind their horned counterparts in terms of quality and performance. However breeding programmes around the world have greatly reduced that gap. Indeed, the number of polled beef and dairy bulls available in Irish AI, although small, is still far greater than it used to be and appears to be growing every year.
AI Bulls
Angus and Hereford have always been the most well known breeds for polledness. However, in recent years the percentage of polled animals is increasing across many different breeds. Outside of Angus and Hereford, a total of 180 polled AI bulls have been used in Ireland to-date. They range across 18 different breeds, with Simmental having the most with 49 polled AI bulls coded to-date. Traditionally breeders would have just brought in a small quantity of semen from particular polled bulls for their own pedigree matings. Now it is becoming more common for AI companies to carry semen of polled bulls from these other breeds as well as standing such bulls in their studs.
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