The Poll Highland

Inheritance of the poll/Horn gene

Horn poll parentage

Parents and its offspring

In long haired cattle without horns of European ancestry, the trait of being polled or having horns is determined by one pair of genes. One gene in the pair is inherited from the dam and the other from the sire. The polled gene (P) is dominant to the horned gene (p). If an animal has two polled genes (Pp) homozygous, or one polled and one horned gene (Ph), heterozygous, it will be polled. However, if it is heterozygous polled (Ph) it may pass either the polled or horned gene on to its offspring. The only situation when an animal will be horned is when it possesses two recessive horned genes (HH), homozygous horned. Table on the right had side illustrates the expression of a poll or horned animal and what genes and traits can be expected to be passed to the offspring from the various mating.If an animal of European breeding has horns then you can determine from visual observation that it is homozygous for the recessive horned gene. However, if the animal is smooth polled or scurred it is impossible to determine from visual observation if it is genetically homozygous polled (PP) or heterozygous polled (Ph). The homozygous polled bull with two polled genes will sire only polled calves. Only through the offspring produced can the number of polled genes be determined. The best test of a bull for breeding to horned cows is to mate the polled bull in question to horned cows. A polled bull bred to horned cows that produce one or more horned calves is heterozygous polled (one recessive gene for horns), regardless of how many polled calves are produced. The Table below gives the probability of a polled bull being homozygous polled if no horned calves are produced from a mating with horned cows.

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The offspring will inherit one gene from each parent, chosen randomly. If it carries either one or two poll genes, then the animal will be poll. If the parent is a Ph (Carrying a poll gene and a horn gene), it can pass on the poll or horn gene depending on the other parent.
 The 3 Genes combination (Pp) = Homozygote Poll, (Ph) = Heterozygote Poll or (Hh) = Horned are highlighted (In brackets)

Identifying calves that are horned or poll

is not always easy. Feel the top of the head of the newborn calf, you can usually feel the horns under the skin; they will feel like matching little bumps under the skin where the horns would be. If you can' feel them it is most likely a poll calf. Check a week later to be sure. A peaked poll indicates an animal that is naturally poll. Calves which have a rounded almost flat head are indicative of them developing horns later usually coming through the skin by 6 weeks of age. Six weeks of age is a good time to dehorn as this is before the horn attaches to the skull bone. Dehorn: There are several ways to dehorn your calves and the preference of method is up to the individual. Different methods are as follows - As calves you can scallop the horn buds out with a tool at about 6 weeks old OR burn them with either an electric or gas de-budder.It is all over in a couple of minutes and the calves recover very quickly. Older Cattle - You can simply cut the horns off with the wire cutting method, or cut them off with the dehorner. Or you can cut the horns off with a sabre saw; it lessens the bleeding of the horn. Use the white fine metal cutting blade. It is definitely advisable to do this in winter as the flies will be a problem in summer.
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Each parent has 2 horn or poll genes, and will pass on one gene each to its offspring. Sire Dam Offspring Horned (Hh) + Horned (Hh) = Horned (Hh) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Horned (Hh) + Poll (Ph) = Horned (Hh) or Poll (Ph) ~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Horned (Hh) + Poll (Pp) = Poll (Ph) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Poll (Ph) + Poll (Ph) = Poll (Ph) or Poll (Pp) or Horned (Hh) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Poll (Pp) + Poll (Pp) = Poll (Pp) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Horned (Hh) +Horned (Hh) = Horned (Hh) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Poll (Ph) + Horned (Hh) = Horned (Hh) or Poll (Ph) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Poll (Pp) + Horned (Hh) = Poll (Ph) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Poll (Ph) + Poll (Ph) = Poll (Ph) = or Poll (Pp) or Horned (Hh) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sire Dam Offspring Poll (Pp) + Poll (Pp) = Poll (Pp) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~