Download The Making of the BBRed Rosecomb

The Making of the BBRed Rosecomb
© 2000 Katherine Plumer
*Author’s note: this essay was written for a college English class–a group of people who
knew nothing about chickens. I’ve revised it slightly.*
Author’s note: the gene symbols used within this essay are probably not those that are used
by the science community. Oh well. I have chosen to use symbols that make sense to me.
Also, I make no guarantees as to the accuracy of all the information printed here. This is
what I have seen, but I can’t guarantee that I know what I’m talking about. I am not a
geneticist and don’t completely understand all this stuff anyhow.
Seven years ago I started playing with genetics. What I lack in real genetic knowledge I think
I’ve made up in real experience. I still can’t quite define words like “locus,” but I know how to
work with certain colors. I will attempt to explain here my experience with developing the
black breasted red color pattern on the Rosecomb breed.
I started out with two breeds of bantam chickens: Rosecombs and Old English Games. My
Rosecombs were black, and my Old English were black breasted red (hereafter abbreviated
BBRed), two very different color patterns. So the challenge was to put the BBRed color on
the formerly black Rosecomb body type.
Not only did I have to deal with another color that was already present (this is not like
painting a blank canvas), but the two breeds have some real differences in body type.
Rosecombs are short-backed and long-tailed. Old English are longer-backed and shortertailed, with much shorter and harder feathers. Rosecombs are slightly bigger. Rosecombs
have a different comb type, called a rose comb, which is dominant to the single comb of an
Old English. Rosecombs also have very large white ear lobes, whereas Old English have
small red lobes.
A Refresher Course in Inheritance
(skip this part if you know all this stuff)
I think everyone has heard about Mendel’s experiments with the pea plants. I’ll just stick with
that example and offer a little refresher course in Mendelian and non-Mendelian genetics.
Mendelian genetics were first proven true for something other than pea plants by breeding
for specific comb types in chickens. Flowers are probably a little easier to picture though.
Every trait (flower color, for example) has two genes that code for it. Genes that follow the
Mendelian patterns of inheritance come in two forms: dominant and recessive. Dominant
genes are abbreviated with an upper case letter (PP for purple flowers) and recessive traits
are abbreviated with a lower case letter (ww for white flowers).
Genotype: This refers to the actual genetic makeup of the organism.
Phenotype: This refers to what the organism looks like, regardless of its genes.
Dominant: Let’s say we’re dealing with true breeding purple flowers (meaning they are
100% “pure,” or homozygous, for the purple gene). If two of these purple flowers are
crossed, they will continue to produce 100% purple flowers. If a homozygous purple flower is
crossed with a white (recessive) flower, all the offspring will appear (phenotype) purple. The
dominant purple color is “stronger” than the white gene.
Recessive: As in the previous example, let’s say you breed a pure purple flower to a white
one. White is recessive. In the first generation all offspring would look purple (though each
would carry one gene for white, even though that gene is masked by the dominant purple
gene). If you bred those offspring together, one fourth of them would be white! Recessive
traits only show if the organism has BOTH genes for that recessive trait.
Homozygous: This means that both the organism’s genes for a particular trait are the same
(like PP for homozygous purple, or ww for homozygous white).
Heterozygous: This means that the organism’s genes for a particulate trait are different.
Using the example of these flowers, Pw (a cross between purple and white) is heterozygous.
Although genotypically it carries the white gene, it would be phenotypically purple, since the
dominant gene is the one that’s expressed.
That gets a little more complicated though if the organism does not follow Mendelian
genetics. Then you have to deal with co-dominance and incomplete dominance. These
genes are inherited the same way as a dominant gene; they just look different.
Co-dominance: Again I’ll stick with something easy to picture: flowers. Suppose you have a
type of flower were red (abbreviated RR) and white (abbreviated WW) are BOTH dominant
(genotype RW). If you breed them together the genes produce an equal mixing of color, and
you’ll get pink flowers.
Incomplete dominance: But suppose you have another type of flower where white is
recessive (ww), but red is not quite dominant (RR). In other words the incompletely dominant
trait is not strong enough to hide the recessive one. If you breed these flowers together, the
offspring would be splotched with red and white. Because white is only recessive, it is not
strong enough to dilute the red color, but the red is not strong enough to completely cover
the white.
Now let’s talk chickens.
F1, or First Generation
I should first admit that when I first started this project my intention was really not to develop
a new color in Rosecombs. I also knew absolutely nothing about genetics. I just wanted to
see what would happen if I crossed the two breeds. A year later, with some encouragement
from other poultry breeders, I set out to work with color genetics.
BBRed is an incompletely dominant color. Black is recessive. In other words, black will only
breed true if bred to black. If bred to a dominant color, black will be hidden, to reappear after
a heterozygous cross (like the heterozygous purple flowers producing white offspring). Since
BBRed is incompletely dominant though, it does not fully cover up the black, like the red and
white splotchy flowers. Please note that I did not discover the ways that these colors work.
It’s been known for many years.
Since my intention was not originally to work on developing a new variety, I made the
mistake of only using two birds as the parent stock: a BBRed Old English male named Bert,
and a Black Rosecomb female named Rose. If I could start over, I would use at least two
males, and at least two females with each male. But oh well, I can’t go back and redo it now
that I am this far into it. I hatched eight chicks out of those two birds. Four were male and
four were female.
The F1 offspring were all heterozygous, an intermediate color form I call “black-red.” Males
looked somewhat similar to BBReds, though darker, with more striping in the hackles, and no
wing bay (similar to brown red). All the females were black with a hint of red in the hackles.
All the F1 offspring had rose combs, though very poor quality, and their ear lobes were small,
with excessive red markings. As far as type, they looked a lot like Old English, but they had
rose combs. They did not have the short backs and large tails needed in the Rosecomb
breed.
F2, or Second Generation
I knew that if I crossed the heterozygous offspring from the first generation together, I would
get the BBRed color pattern that I was hoping for (since at this point I really was trying to get
BBRed Rosecombs). But I would still have to deal with incorrect body and comb type.
I kept the best F1 male (the one with the least amount of red in his ear lobes) and bred him
to the four F1 females. About twenty chicks hatched, and as expected about five of them had
single combs instead of rose combs (since single is recessive to rose, the heterozygous
cross produced one-quarter single combs and three-quarters rose combs). They all had
small white ear lobes, with varying amounts of red showing through. None had the short
back that is required of the Rosecomb breed.
The second generation produced quite a few colors. Three females came out BBRed, though
far too dark. One male was BBRed, but as luck would have it he died before breeding
season. Several males were black-red (like the first generation), and some were black. Quite
a few females appeared black, but I could not tell which were homozygous (pure) black and
which were heterozygous black (meaning they only appeared black, since they also carried
the gene for BBRed). I also hatched one surprise, a brassy back female. This was totally
unexpected, but I was happy to see that I was starting to develop two colors! Unfortunately, I
do not know enough about genetics to explain how that color happened to show up.
F3, or Third Generation
I had no “rules” to go by to tell me what to do. I just had to guess which birds to use to get
the desired color and type. So what I had at this point was the right color and the wrong body
type. I knew that if I continued to breed the birds together there was no way I could improve
their type, because they were still 50% Old English. So I decided to cross them back to pure
black Rosecombs to shorten their backs and increase their tail size, as well as improve their
combs and ear lobes.
The three BBRed females, as well as the brassy back female, were placed with a black
Rosecomb male. I would have put the BBRed male with black Rosecomb females, but since
he died…I couldn’t. Instead I selected the best looking black-red male to use instead, and to
this day I wonder if anything would have been different if I had been able to use a BBRed
male at this stage of the game.
The offspring were similar to those in the first generation, regardless of which mating they
were from (since color is not sex-linked in this case). All females appeared black, though
some were heterozygous and some were homozygous. Some males were black
(homozygous) and some were black-red (heterozygous). They started to look a lot more like
Rosecombs in this generation. Their tails were large, as were their white ear lobes. They had
good rose combs, but their backs were still a bit long.
F4, or Fourth Generation
This generation was similar to the second generation. I kept the best black-red male, and
bred him to the eight best females, although I could not distinguish black females from blackred females because they look almost exactly the same. It did not matter to me if these birds
had a black mother or a black father, since the genotype is the same either way.
From this cross I hatched one BBRed male and a few BBRed females (all a bit dark), a trio
(one male, two females) of excellent brassy backs, and numerous blacks and black-reds.
They looked really good in just a matter of years, and the BBRed male even won Reserve of
Breed at a well-known show. In just four years, I had developed two new colors of
Rosecombs.
F5 and later generations
I sold all but the BBReds and brassy backs. I have just been breeding the BBReds to each
other since then. To avoid weakening from inbreeding I occasionally make a small outcross
to another variety of the same breed (like blue breasted red Rosecombs). This just keeps
them a little more genetically diverse. They look great now. Their body shape is identical to
that of the black Rosecombs, and their color gets better every year, though still not as good
as you would see on a BBRed Old English. They will continue to improve, though, and be
more consistent in quality with every generation.
The brassy backs have done well too. Though they were not what I intended to develop, I
have done so anyway, and last year I bred them back to black Rosecombs to try to get their
ear lobes a little bigger. Within a few years I should be able to get brassy back Rosecombs
accepted into the American Bantam Association standard so they can compete with the
other varieties at shows.
I am now eight generations into my tinkering with chicken genetics. I am happy with what I
have achieved. Rosecombs used to exist in many more colors (twenty-six) than they
currently do (usually only four colors seen at shows), and since none of that old stock is still
alive I am doing what I can to bring them back, and throw in some new colors too while I’m at
it. I will probably keep doing this sort of thing for my whole life if I can. This might sound
strange but it’s really satisfying to see the colored Rosecombs making a comeback now. I
guess maybe this is just what happens when you have an interest in art and chickens…