MTT develops an effective solution to a worldwide quality problem in hens’ eggs which causes fishy odour in brown eggs
MTT Agrifood Research Finland has identified in a collaboration with the German Institute for Animal Breeding Mariensee (Federal Agricultural Research Centre, FAL) and Lohmann Tierzucht GmbH a genetic defect, which impairs the quality of brown eggs by producing a fishy odour. The MTT research team has also developed an efficient procedure to test for the defect. Lohmann Tierzucht (LTZ), one of the world’s largest chicken breeding companies, has already begun to apply this procedure, and marketing of the first chicken parent stock free of the defect will begin worldwide at the end of the year.
The fishy taint occurring in brown eggs has caused major problems for chicken breeders, producers and trade in the EU, where most hens’ eggs consumed are of the brown variety. In Finland, however, brown eggs account for less than 10 percent of all eggs sold.
At worst, the smell of rotting fish can be so strong that it persists even the cooking of eggs. When trade buyers find tainted eggs through spot checks, the producer faces significant loss as the entire batch must be withdrawn from sale. The problem is most severe in Central Europe.
The cause of the odour is in a gene which animal biotechnology researchers from MTT mapped. The MTT researchers demonstrated that the genetic defect they had pinpointed is the precondition for the presence of the odour. The result of their findings is to be published in Genomics and can already be viewed at the magazine’s online website. ‘The white chickens do not carry this mutation’ clarified Johanna Vilkki, Principal Research Scientist at MTT and leader of the research team. ‘Furthermore, the eggs of brown chickens do not smell unless chickens which have inherited the genetic defect have been given feed containing an ingredient which triggers the taint, for example rapeseed. Approximately 5–10 percent of brown chickens which consume such feed produce tainted eggs.´
An unequivocal tool for breeding
Through the results of their research MTT have developed a simple and inexpensive procedure for testing chickens. DNA testing is usually done from blood samples, which is not only complicated and expensive, but may also be traumatic for chickens. MTT’s testing procedure only requires one feather to produce an unequivocal result. ‘Cells from the feather shaft indicate whether a chicken has the genetic defect. The procedure makes it possible to select brown chicken lines for crossbreeding to ensure that progeny do not have the genetic defect which causes the odorous taint,’ explains Johanna Vilkki.
An international patent has been sought for the testing procedure. Marketing of selected lines will begin at the end of the year and the first newly-hatched chicks free of the defect will be on sale in August 2006. These hens will be of egg-laying age from the start of 2007. According to Professor Asko Mäki-Tanila, MTT’s Director of Animal Production Research, MTT is currently developing procedures which use molecular genetics to identify hereditary defects in pigs and cattle, too.
Chicken breeding completely phased out in Finland
The discovery of the genetic defect and the development of the testing procedure represent one result of the many years of close cooperation between MTT and Lohmann Tierzucht of Germany, to find solutions to quality defects in hens’ eggs. Germany’s Federal Agricultural Research Centre (FAL) Mariensee also participated in the research. Globally there are now only three chicken breeding companies. Of these, Lohmann Tierzucht is the European market leader. It holds a quarter of the world market and approximately 70 percent of the Finnish market. In Finland chicken breeding was completely phased out some ten years ago.
MTT’s animal biotechnology researchers have previously received international recognition for their work in bovine in vitro fertilization and embryo diagnostics, and in gene mapping in livestock.
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