Polled vs Horned Goats
A customer called a little while ago wanting to purchase a few goats and asked about our polled first freshener. His question was specifically regarding whether the polled trait would be carried through the male or the female. Well, good question! For those of you who have not completed a college genetics class, let me answer this as simply as possible – traits (carried in the DNA of chromosomes) come from both parents. It is the combining of those traits that determines whether you will get a polled goat or a horned goat.
Horned Goats.
Nigerian Dwarfs are born with horn buds. If a breeder chooses to leave the kid’s horn buds intact, they will begin breaking through the skin just days after birth and will turn into horns as they continue to mature. They begin growing at a rapid pace. That is why disbudding kids early on is important if you prefer goats without horns.
Polled Goats
goat that is born naturally hornless is called “polled”. There is no disbudding required for these goats. In place of the horns, there are two rounded bumps or nubs that you can feel but they will not grow into horns. Newborn or very young polled kids can often be differentiated among horned kids by the lack of a “swirl” of hair where the horn bud would normally come in. Most horned kids will have these small hair swirls where the buds will start to break through the skin; polled kids usually lack the swirls.
Because many producers like the idea of goats without horns, breeders often times select their breeding pairs specifically for a goat’s genetic disposition that enables them to throw polled kids. Well, here is how it works:
Terms to know:
Traits – different forms of the same characteristic, like eye color.
Genes – the portion of DNA that contains the genetic code for a trait.
Chromosome – genes are located on chromosomes.
Allele – one of two (or more) alternate forms of the same gene. For example, long versus short eyelashes or horns versus polled.
The polled gene is considered dominant, which means, if the polled gene is present at all it will result in polled offspring. A kid can be polled if one or both of its parents are polled. In other words, if both parents are horned, they will not produce polled kids.
The gene for horns has only two alleles or characteristics to consider, polled or horned. We can designate each by these with the symbols P (polled) and h (horned). That means there are only three possible genes that any goat can have when it comes to horns. They are:
PP – This animal is polled and considered Homozygous (two polled alleles). Cannot produce horned offspring, regardless of mate.
Ph or hP – This animal is polled and called Heterozygous (one polled and one horned allele) and carries a recessive gene. Can produce both polled and horned offspring, unless bred to a homozygous polled mate.
hh – This animal is horned. Cannot produce polled offspring unless bred to a polled mate.
Horns are the result of two recessive genes which are indicated here by the lower case hh for “horned”. Although obvious in the chart above, you would not be able to tell the difference in a polled animal that carries two dominant genes from one that carries one recessive gene for horned. This explains how it is possible to breed two polled animals and still have some offspring with horns. This would indicate that both parents carry a recessive gene for horns.
Sound complicated? It’s not, until you start considering nature and statistics. For instance, if you had a horned female (hh) and a heterozygous sire (Ph), you have the potential for 50% of the kids to be polled (see chart above). However, in any one year you could get all horned or all polled or a combination of polled and horned. This exact scenario occurred with one of our doe’s last year. Two breeding seasons ago, she was bred to a polled sire. All three kids were horned. Last year she was bred to the same sire. When triplets were born, the two doelings were polled and the buckling was horned. With that knowledge, you can ascertain that the mother doe was (hh) and the sire was (Ph). From this information you can conclude that you have 50% chance of getting a polled kid when using this sire with a horned dam.
So, to answer my customer’s question in the first sentence – will our polled doeling (Ph) throw polled kids? The answer is yes; 75% of the kids will be polled if bred to a sire who has a heterozygous gene (Ph) and 50% of the kids will be polled if bred to a horned sire (hh). But now you just have to wait for nature to roll the dice as the percentages don’t always hold true in a particular year.