Silhouette

Brian Reeder

An Overview

The silhouette is the outline of the bird. It is a solid black image that focuses attention on the outline of the form.

The definition of ‘silhouette’ from Wikipedia is: “silhouette; the image of a person, an object or scene consisting of the outline and a featureless interior, with the silhouetted object usually being black. Traditionally, a silhouette is a form of artwork, the term originating in the 18th century and applied to portraits or other pictorial representations cut from thin black card.”

In poultry breeding, we use the silhouette to understand how the various traits we are selecting for in our lines create a unique outline, recognizable when completely devoid of detail.

All the classical exhibition breeds are recognizable by silhouette alone if you have much experience with poultry at all. A glance at the silhouette of a Polish makes self-evident what is being indicated, and so too with the Cochin or the Japanese Bantam. Each of the junglefowl shows unique and discernable silhouettes, and while some Asian Game strains are called jungle fowl, their silhouette makes it immediately apparent that they are not really jungle fowl at all, but very modified domestics.

When lines are well selected for the expression of their target form genes, combinations occur that are very recognizable, once you have some familiarity with the breeds either through maintaining them or seeing them regularly at shows.

The common denominator is the silhouette, the outline of the bird, regardless of any factors. Certainly, some recognizable color varieties immediately tell you what you are likely seeing, such as mille fleur, but the D’Uccle is recognizable based on its outline rather than only one of the breeds many color varieties.

There are instances of overlap with some breeds. Some bantam Cornish might be hard to tell apart in silhouette from some Japanese Shamo bantams while some of the simple formed breeds, being jungle fowl like in form, can be harder to tell apart in silhouette unless you are very familiar with them.

Many of the American breeds are very similar in silhouette, but this should come as no surprise as they all have common ancestry through Chinese fowl imported in the mid to late eighteen-hundreds.

These again can be harder for the un-experienced to tell apart. However, a Rock and a Cochin are not mistakable for the other and are immediately distinguishable by their outline, and neither would be mistaken for an Onagadori, whose silhouette is vastly different from the other two. So how can we begin to understand how the Genes of Form and Feathering come together to make the silhouette?

Silhouette as Composite of Form and Feathering Traits

Three groups of heritable factors come together to make the silhouette: skeletal, muscular and feathering. This is not to imply that any of the genes within any given group is related in any way, only to put them into three easily recognizable groups to make our purpose of understanding the silhouette easier. The subject of the genetic factors of these three categories is complex and some of these factors are quantitative in nature.

With the release of my latest book, ‘An Introduction to Form and Feathering of the Domestic Fowl’, I have documented many of these factors. I have classified the heritable factors I discuss by the three categories that make up the silhouette; skeleton, muscles and feathering with the comb-type crowning the silhouette. I will list here from the contents some of the genes I discuss in the book that relate directly to the silhouette.

Genes of Form and Feathering

Skeleton

Wild Type

Extension

Shortening

Horizontal/Vertical

Tail Bud, Tail Angle and Taillessness

Polydactyly

Muscle

Wild Type

Muscle Increase

Muscle Decrease

Feather

Wild Type

Fast and Slow Feathering

Feather Shortening

Feather Lengthening

Feather Count

Feather Thickness

Hen feathering

Leg Feathering

Vulture Hocks

Tight and Loose Feathering

Hookless

Frizzling

Crest and Tuft

Muff and Beard

Ear Tufts

Nakedness

Comb and Wattle

Single Comb

Rose Comb

Pea Comb

Duplex Comb

Buttercup Comb

Composite Combs

Comb and Wattle Size

As you can see, there are many heritable factors involved in the three categories that make the silhouette. The discussion of those genetic factors is too long for this article, but we can briefly consider the three categories and how they come together to make the silhouette.

Building The Silhouette

The skeleton is the structure upon which all else is based. The skeleton genes will determine how everything else is distributed. The muscles are arranged upon the skeleton and it is the skeleton that determines the plains of the form, the angles that determine the kinesthetic orientation and the center of gravity.

Skeletal genes can make a shortened form with short extremities (neck, legs, etc) and a forward tilted orientation wherein the center of gravity is to the front of the body, or skeletal genes can make a vertical form with long extremities and the center of gravity directly over the legs.

These are but two extremes and a wide range of phenotypes are seen in between them. The wildtype skeleton of the jungle fowls is generally horizontal with the center of gravity to the center of the body, just in front of the legs, over the front toes. When excited, jungle fowl may raise the front part of the body and the center of gravity shifts back slightly centering over the legs. When they travel in brush they drop the front of the body down and the center of gravity shifts forward slightly. The three major stances of jungle fowl are exaggerated in the many phenotypes seen in the domestic fowl. These variations all originate in the skeletal genes.

Once the skeleton is in place, the muscles layer on the skeleton and fill out the form. The level of muscling, either increased or decreased, fills out the body of the bird.

To get a good idea of how muscling can change the form, think of this progression; Modern Game - Jungle Fowl - Cornish. The jungle fowl represents wildtype while the Modern Game is muscle decrease and the Cornish is muscle increase. These two variations on wildtype are quantitative, so this is not a case of two simple genes. It is also important to bear in mind that feathering can disguise muscling. Loose feathers on decreased muscling can mimic muscle increase. Extremely profuse breeds such as Cochin may appear robust, but this is too often not through muscling. The surest method to determine muscling in any bird that is not tight-feathered is to simply handle the bird. Marek’s Virus can cause muscle diminution and this can often be mistaken for muscle decrease as in Modern Game.

It is not the same and many breeds that are small or profusely feathered show the effects of Marek’s that shouldn’t. Marek’s virus is common in our poultry but recent research shows there to be several variations of genetic resistance for Marek’s, so selection for resistance can eliminate that form of undesirable muscle diminution.

Feathering is the glory of our fowl. Feathers define birds. There are many feathering genes in our domestic fowl. The most important and fundamental variation is tight, hard feathering and loose, soft feathering. The subject of feathering in the domestic fowl is complex and there are several quantitative factors.

Since it is such a large topic, it is impossible to discuss here, but I cannot stress enough how vital the feathering genes are to the finished silhouette. Just image what a Cochin might look like with no feathers, as compared to what a Cornish would look like with no feathering. Finally, the comb genes make the crown that sits upon the head of the silhouette. While the comb is a small point in the overall silhouette, it is the finishing touch.

Applying the Silhouette to Breeding

Silhouettes are easily made in any paint program. I use a free version of Gimp. Using a picture of your own bird in a side stance, use the paintbrush to white out the background and then blacken in the bird. You may need to increase the screen image size at times and you will need to use variable sizes of the paintbrush, but it is very easy to do. Once you have turned your bird into a silhouette, find or make a silhouette of show winning birds or standard images.

Compare your bird’s silhouette to the standard and/or exhibition winners. In this way, you can find the weak points in your bird’s overall form and aim your breeding toward correcting the problem areas. It is very helpful in selecting birds for phenotype to become acquainted with the desired silhouette as well as the silhouettes of your own birds. This can be an invaluable tool in selecting toward the desired type in any breeding endeavor. It is also a wonderful way to step back from color selection and consider the form. I hope you try making your own silhouettes. I believe you will find it a useful tool in the breeder’s toolbox.

Press Release: An Introduction to Form and Feathering of the Domestic Fowl

Press Release: An Introduction to Form and Feathering of the Domestic Fowl

Sunday May 22, 2011

An Introduction to Form and Feathering of the Domestic Fowl
By
Brian Reeder

This informative new volume is the second release in Mr. Reeder's series of guide books to breeding and genetics. Specifically dealing with the Domestic Fowl, the ubiquitous chicken, this volume deals with form, complimenting the first book in the series, 'An Introduction to Color Forms of the Domestic Fowl'.

In this introduction to the genetics of form and feathering of the domestic fowl you will find a straightforward method that allows anyone, beginner or advanced hobbyist, to understand how the major genes of forms and feathering come together to create the silhouette that is the hallmark of each breed. Beginning with a discussion of the skeleton genes, then moving to muscling genes, feather genes and finally to comb genes, an understanding of the layers that make the silhouette is revealed. From this system of understanding how the silhouette is formed, one can then understand what really makes one breed unique from another.


All of the genes presented herein are found in the commonly seen exhibition breeds and many hobbyists will be familiar with these breeds, but may be less familiar with the genetic factors involved. This volume is a wonderful tool for learning the basis of how the breeds are made, how their respective forms are derived from separate genes of form and feathering, and how those genes all come together to make the form of any given breed. Many genes are required to derive each type and the combination of those many genes creates the silhouette. As you will see from the many silhouette illustrations on this book, once you know a breed, it is instantly recognizable from the silhouette alone.


In addition to the discussion of the genes, there is a discussion of basic genetic concepts and of the complex and often confusing method of quantitative that is very applicable to many of the genes described herein. This book presents a very clear system for learning about the genetics of form and feathering in the domestic fowl and is written to be understood by the young and beginners alike.

Available at Authorhouse.com and Amazon.com

An Excerpt from the newly released... 'An Introduction to Form and Feathering of the Domestic Fowl'

Quantitative Traits and Selection Methods

By
Brian Reeder


Quantitative traits are common in the phenotypes of domestic fowl. Unlike qualitative traits that produce the classic 1:2:1 pattern of inheritance, quantitative traits vary over a continuous range and are the result of alleles of two or more genes. Large numbers of birds are needed to select for traits of a given preferred combination. In observing a group of birds, one should note the range of expression of a given trait. As an example, let us consider the single comb for a moment. When I say single comb, we all have a basic agreement about what that word means. It is a blade comb, flattened with triangular teeth or points at the top row. In this basic regard, the description is exact, but we all know from observation and experience that the expressions of the single-comb can range tremendously. Combs can be huge and tall and very thick, or they can be large and thin, flopping easily and very susceptible to frostbite. There are tiny single combs that are thick and tiny single combs that are very thin in width.

Some single combs are rough while others are smooth. The numbers of points varies widely as does the exact size and shape of the points and the blade section on the back. Folds, lines, creases and many other strain-specific traits are also seen on this comb type. Some lines of single comb birds are deeply homozygous for their phenotype expression and their single comb expression breeds true and may be very prepotent in outcrosses. Other lines are segregating for a given number of traits and so their single combs are not of one consistent form. Consistent gene expression in the phenotype implies homozygosity for the alleles in question.

As an example, let us say you want to make a small thick comb that does not get frostbite. You have set out a parameter for a trait that may represent more than one gene. You begin by selecting those birds that express the individual traits you want to combine as well as those that are coming closest to the ideal expression.

As you blend each generation, you are looking for intensifications of traits as well as further recombination, working to bring all traits together as homozygous in one population. In each generation you will be looking for an increase of percentage in the given areas of selection, with an eye toward a total increase of multi-trait expressing individuals.

In our single comb example, you would note and select those with rough combs, small combs and thick combs. Those that had two traits combined and those that had three traits combined would also be noted and they would be given some level of preference. Multiple mating schemes could then be employed for both blending traits to get the multi-gene recombinant homozygotes and for intensifying the expression of homozygosity in recessives in general. Each generation should show an increase in the desired traits if your matings are well planned and you know what you are looking for. Each population or line within the over-all group is scored for every trait in the set of traits being selected for. In this way, the percentages of increase for any trait can be gauged in each line of the population.

To manage quantitative selection you need to pay attention to trends in the population. Those birds that show the greatest expression of desired traits are the most likely candidates to further express the trait and for enhancing expression into a more extreme (homozygous for a very specific combination) expression. This is easily done when the background genetics support the expression of the desired traits, especially if many or all of those traits happen to be dominant factors, making their early expression more obvious. Selection for major phenotype groups of factors may actually be practicing some level of selection on many, many more alleles than the simple explanation of single gene traits would imply.

With recessive genes or when both dominant and recessive traits are involved, the production of homozygotes is necessary to see the recessive effect. This can make selection more difficult. In the case of a recessive trait, pedigree is much more important, as recessives cannot be seen in the phenotype. Thus, you may find yourself frequently working with generations that do not express some or all of your desired phenotypic expressions.

The recombination of phenotypic expression in a multi-gene recessive scenario is difficult and requires a multi-pronged approach, patience, good record-keeping, large numbers of birds, and a focus on homozygotes. In this instance, we may only see very small incremental increases in gene expression for the total expression of all involved alleles for several generations. Yet, as later generations reach high expressions of homozygosity, the numbers will tilt and the population expression will begin to be set and express in high percentages.

In summary, quantitative selection is picking those that look the most the way you want them to look and selecting in that direction each generation. You may need to be patient if you are working toward expression of a large number of recessive traits. With dominant traits, you may get faster results due to being able to visually identify heterozygotes. Select for those birds with the most traits you want and as you see some increase (even if just a five or ten percent increase per generation) then you are heading in the right direction.