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A full-scale breeding program was commenced in 1958, with commercial shipments in Canada and the US in 1959 and in Europe in 1963. [7] As a second example, color sexing broilers was proposed by Shaver in 1973. The genetics were based on the company's breeding plan for egg layers, which had been developed in the mid-1960s.
Broiler breeder farms raise parent stock which produce fertilized eggs. A broiler hatching egg is never sold at stores and is not meant for human consumption. [9] The males and females are separate genetic lines or breeds, so that each line can be selected for optimal traits for productivity in either females or males, rather than a single line in which a compromise is reached between female ...
Poultry farming is the form of animal husbandry which raises domesticated birds such as chickens, ducks, turkeys and geese to produce meat or eggs for food. Poultry – mostly chickens – are farmed in great numbers. More than 60 billion chickens are killed for consumption annually.
Poultry breeding has produced breeds and strains to fulfil different needs; light-framed, egg-laying birds that can produce 300 eggs a year; fast-growing, fleshy birds destined for consumption at a young age, and utility birds which produce both an acceptable number of eggs and a well-fleshed carcase.
Selective breeding has been responsible for large increases in productivity. For example, in 2007, a typical broiler chicken at eight weeks old was 4.8 times as heavy as a bird of similar age in 1957, [36] while in the thirty years to 2007, the average milk yield of a dairy cow in the United States nearly doubled. [36]
Following the Treaty of Wanghia between the US and China in 1844, oriental poultry breeds were imported to New England, and Rhode Island became the nation's first major poultry center. [3] Cross-breeding between English and Asian birds created new breeds still common today, like the Barred Plymouth Rock.
The vertical integration of the egg and poultry industries was a late development, occurring after all the major technological changes had been in place for years (including the development of modern broiler rearing techniques, the adoption of the Cornish Cross broiler, the use of laying cages, etc.).
An example of this is in the Eurasian bullfinch which exhibits relaxed selection and sperm competition. The sperm of these males have a lower velocity than other closely related but polygamous passerine bird species and the amount of abnormalities in sperm structure, length, and count when compared to similar bird families is increased.