Breeding Chickens for Egg and Meat Production
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By Doug Ottinger – Let’s face it. Few of us raise poultry in our backyards because there is some great financial advantage in doing so. Some of us do it because of fascination. Some for showing birds. Others to provide healthy food. And a few of us raise eggs or meat for small markets.
If you like to breed your own birds for eggs or meat production, or are fascinated by cross-breeding birds and seeing what new external traits show up from all of those hidden genetic factors, this article just might be for you.
Time Needed to Fully Establish a Trait
A general rule-of-thumb is that it takes at least five generations to firmly establish a trait in a line of birds. This is only a guideline. Some traits might take three generations to establish. Others might take seven or eight generations. The main thing is to not get discouraged if the trait you want to establish does not firmly establish itself quickly. Be patient and don’t give up.
Breeding for Eggshell Color
As far as chickens are concerned, did you know that there are only two colors of eggshell? The two shell colors of chicken eggs are white and blue. This blue color is the result of a dominant genetic trait. The dominant gene factor, for this trait, was discovered by the noted geneticist, Reginald Punnett, in 1933. He assigned the gene symbol O to the trait, and we still use it, in our genetic coding today. The blue color of the shell is caused by a pigment called oocyanin, which is a byproduct of bile. Some chickens carry the gene that puts this color into the eggshell, but most do not. The pigment is actually mixed into the composition of the shell, so the shell itself is actually blue throughout. But what about brown, green, and olive eggs? The brown pigment, protoporphyrin, which gives the color, or hues, to the shells of brown, green and olive eggs, is actually only on the outside of the shell and is not part of the calciferous compound that constitutes the actual shell. Just as the paint on the walls in your house is not an actual part of the drywall or plaster, the brown and green hues on the shell are not a part of the actual shell formation. These colors are applied to the eggshell, in the uterus portion, in the chicken’s oviduct, after the egg is formed.
A patriclinous trait is a genetic trait heavily influenced by the paternal side. A matroclinous trait is a genetic trait heavily influenced by the maternal side. Did you know that the intensity of the brown color on the eggshell is heavily influenced by the hen’s paternal ancestry?
This brown pigment is actually from the breakdown of hemoglobin in the blood. The making of brown eggs is controlled by several genetic factors in the birds. The traits are neither dominant nor recessive. They are somewhere in-between. When dark-brown egg-laying breeds are crossed with white-egg producing breeds, the resulting female offspring produce eggs that are in-between in color. However, if a brown-egg breed is crossed with a blue-egg breed, the resulting female offspring will lay eggs that are shades of green. If very dark-brown egg-layers are crossed with blue-egg birds, the resulting female offspring will produce eggs that are a dark olive-green color. The genetics of these crosses were first researched, and reported on, by Punnett, in his reports on the genetics of blue egg-production, in the early 1930s.
Eggshell Quality is also Genetically Linked
Eggshell quality is crucial whether the eggs are produced for eating or hatching. Poor-quality eggs often do not hatch well. They are also more prone to rapid deterioration when stored as a food product. Shell quality is one of the easiest things for a poultry keeper to change. Most obvious is to provide your birds with an adequate supply of calcium and other trace minerals. Ability to process calcium into a high-quality eggshell is a genetically linked trait. Research as early as 1909 showed eggshell quality was linked to heredity and selective breeding. Research continued into the 1930s and beyond, all with the same findings. Traits of poor shell quality were easy to correct in breeding flocks and often markedly improved within three generations of selective breeding. If you’re breeding at home, you should not use eggs of poor shell quality unless they are the only ones available to reproduce a certain trait.
Comb Selection May Be Important
A chicken’s comb is actually considered to be an external organ. Made of highly specialized and highly vascularized tissue, the comb helps maintain proper body temperature. The arteries and veins crisscross each other in such a manner, that heat exchange continually takes place between them. As blood is pumped through the comb, a series of shunts open and close to regulate the flow.
Chicken combs come in many different forms with nine types recognized by the American Poultry Association. Some combs are the result of clearly dominant or recessive genes. Pea combs and rose combs are dominant. Straight combs are recessive. Other types are the result of genes that are neither fully dominant or recessive. In reality, there are at least 36 basic variations of chicken combs.Choosing to breed birds that are environmentally fit for the region where you live is one way to practice responsible livestock stewardship. It is also a practice that will help you develop your own sustainable breeding program.
Body Size
If you raise and breed purebred fowl, there are standard weights and body conformations established for that breed. Even if you enjoy the results of crossbreeding, you still have to concentrate on desirable body sizes. If you have several different types of birds and just let them breed at random, you will end up with an amalgamated mess, including all colors of feathers, all sorts of combs, undesirable ranges in egg size and production levels, as well as a vast range of variance in body conformation and sizes. From a genetic standpoint, such a flock can be interesting. However, the reality is that such a breeding program is also a nightmare if you are trying to establish set traits for home egg or meat production. Such flocks have a way of losing desirable traits that you may want them to keep. From a genetic standpoint, there may be one plus because such flocks seem to have a “survival of the fittest” condition when it comes to staying well and avoiding disease. However, what you lose in other traits may not make up for it. If you’re breeding your own birds for meat or eggs, you do not have to meet someone else’s set standards or mandates. You are free to make that determination for yourself. However, by and large, one of the best things that you can do in your breeding program is to find a desirable body size and type that seems to get you the desired results. From a production standpoint, this is much more important than working on other traits.
Dwarf Birds
Other than owning and raising bantams, most people will never deal with other dwarfing genes or factors. Most poultry owners know when you breed a bantam with a larger bird, the resulting offspring generally grow to be a size between the two parents. At one time, it was thought that there was one, incompletely dominant, dwarfing gene responsible for the smaller size in bantams. More recent research indicates that several modifying alleles, all working together, are more likely responsible for this trait. One type of dwarfism that’s useful in the commercial meat bird industry is a sex-linked recessive dwarfism. While it is considered recessive, females, which have only one of the genes in their genetic makeup, are still about 32 percent smaller than birds that don’t have the gene. When bred to normal-size males, all of the offspring are normal size. This trait has been introduced in some broiler lines, to produce hens for breeding that consume less feed and can be kept in smaller enclosures. About 18 to 20 percent of the European meat bird industry now uses these hens. Because this type of genetic material is proprietary for industry, it is closely guarded, and it is unlikely that many people will be able to procure these birds for home breeding projects.
Sources:• Hutt, F.B., PhD., D.Sc., Genetics of the Fowl, McGraw-Hill Book Company, 1949. Jull, Morley A., Poultry Husbandry, McGraw-Hill Book Company, 1951.• https://en.wikipedia.org/wiki/Dwarfism_in_chickens • http://sellers.kippenjungle.nl/page3.html Chicken Genes of Common Interest • https://www.uspoultry.org/ • Wole A, et al., Genetic Parameters of Egg defects and Egg Quality in Layer Chickens, Oxford Journals, Science and mathematics, Poultry Science, vol. 91, issue 6, pp.1292-1298 • Zhang, L.C., et al., Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, PR China. Report printed in Poultry Science, 84:1209-1213. Published 2005. • Evanhoe, Rebecca, So Ordinary yet so Versatile, Eggs are a Complex Scramble of ChemicalCompounds; Chemical and Engineering News, August 21, 2016; vol. 84, no.34, p. 49.
Originally published in Backyard Poultry and regularly vetted for accuracy.
