Researchers Look at Genetics That are Linked to Chicken Weight Gain

To help farmers in their quest to increase the weight of their roosters and hens, researchers have been interested in searching for the specific genetics behind weight gain in chickens, known scientifically as Gallus gallus.
Using a distinctive experimentally-bred population, scientists from Uppsala University researched the genetic architecture behind chicken weight. Led by Örjan Carlborg, the research team used two different bred lines of Plymouth Rock chickens to explore weight adaptation. In their study, the researchers used an advanced inter-cross line which was founded by breeding the low and high weight lines after forty generations of selections. In the high-weight line, the average 8-week body weight was 1.412kg compared to the low weight counterparts that weighed 170 g. (About 12 % of body weight compared to the high weight line)
Using the 15th generation of the inter-cross line between the low and high weight lines, the scientists identified 20 genetic loci. Examination of these genetic loci allowed scientists to explain over 60 % of the additive genetic variance for the particular trait.
The researchers further focused on few genetic hotspots (7 of 20 genetic loci), referred to as quantitative trait loci. They found that only two could be mapped to one, well-defined loci; others had linked loci with numerous gene variants. The comprehensive dissection of the loci that contribute to the polygenic adaptations in chicken lines does provide a good understanding of the genome-wide mechanisms that are involved in the long-term selection responses.
Although the selection responses for weight were due to numerous loci of small individual effect, the genetic mechanisms in the specific loci were more complex than presumed in the model. The researchers now hope to further examine this chicken model system to increase understanding of the genetic mechanisms of weight adaptation.


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