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Poultry Genetics


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    This publication provides information on the Cornish-Rock crosses in outdoor production, discusses several slower-growing breeds and provides information on hatcheries that offer these alternative breeds.three chicks

Poultry have a rich history of diversity; however, the large-scale poultry industry has focused specifically on hybrids for meat or egg production. Meat birds have been selected for rapid growth and high yield and, in the U.S., the industry works almost exclusively with these commercial fast-growing hybrids. The Cornish x White Rock cross is used for broiler (meat chicken) and the Broad Breasted White in turkey production.

The fast-growing broiler hybrid produces a large amount of meat with an efficient conversion of feed to meat, growing to market weight of 5.0-5.5 lbs in as little as 6 to 7 weeks. However, the bird is subject to congestive heart failure and heart attacks and often has difficulty walking due to leg disorders. The Broad-Breasted White Turkey hybrid grows so fast and has such a large breast that the birds cannot mate naturally and artificial insemination is needed for reproduction. There is discussion that these hybrids, while impressive meat producers, have been pushed too hard; however, they are used in both conventional and niche production in the U.S. Health of these birds can be improved by slowing growth.

In Europe, commercial slow-growing hybrids are common for specialty markets and are, in fact, required in organic production. Although slow-growing birds may take as long as 12 weeks to grow to market weight, they do not have metabolic and lameness problems.

Although hybrids are almost exclusively used now, in the past, standard-bred birds were used or single-crosses. But genetic companies realized that they could strengthen their intellectual property if they produced double-crossed hybrids. But genetic companies began producing double-crossed hybrid birds, which will not reproduce offspring like themselves if crossed–they do not “breed true.” Instead the producer must buy breeding stock from the breeding company. This provides a biological lock which protects intellectual property.

American standard-bred birds for meat production include Barred Plymouth Rocks, New Hampshires, Delawares, etc. Turkeys include the naturally-mating Bronze, Bourbon Red, Narragansett, etc.. The terms “heritage” or “heirloom” is also used to refer to these standard-bred birds. In the U.S., standard-bred chickens and turkeys have not been selected for meat production since the 1950s and therefore grow very slowly and have a low yield of meat; however, there is renewed interest in selecting them for meat production while maintaining a natural rate of growth.

Slow-growing hybrids and standard-bred birds tend to be active birds that forage in outdoor production systems. Modern fast-growing birds are not well adapted to alternative production because the birds were selected for the sedentary life of indoor production; they are relatively inactive and not able to handle the rigors of outdoor production. If fast-growing birds are grown with outdoor access, it is important to protect them against excessive heat or cold, which limits them to seasonal production.

Selection for fast growth and high yield may have also impacted the eating qualities of the meat. Because birds are slaughtered at an early age, the birds are very tender but flavor may be lacking in the meat. Alternative genotypes, including slow-growing hybrids and standard-bred birds, may have more flavor and firmer texture.

In egg production, the large-scale industry uses white leghorn-type hybrids and brown hybrids. Standard-bred layers for egg production include the Leghorn, Araucana, etc. and for dual purpose (both egg and meat production) include the Rhode Island Red, Dominque, etc. All layers, including hybrids and standard-bred, adapt to alternative production systems because they have normal rates of growth and are active. However, docile layers are needed for cage-free production to help reduce feather-pecking.

It is important to protect endangered breeds of poultry because many are now at risk of extinction. They were left behind by large-scale industry and fell out of use. Interestingly in livestock breed conservation, “Eat it to Save it.” is the slogan. When consumers eat specialty poultry products, producers have an economic reason to grow these birds. Maintaining diversity in poultry genetics will help producers adapt to new challenges including climate change and the emergence of new disease concerns.

Related Video

Master Breeder Frank Reese comments on the adaptation of turkey breeding to large-scale production.


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This page was last updated on: January 26, 2015