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.