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Gains in grain

Project to improve chicken feed efficiency could save energy and millions of pounds

5 January 2011

How many chickens are there in the world? According to the UN's Food and Agriculture Organisation (FAO) statistics database in 2009 there were a mere 18.5Bn chickens, or about three for every person on the planet, alive at any one time (ref 1).

It's a number worth knowing because as the world's population increases and demands a meatier diet, billions more chickens will be farmed. But consider how much food so many birds can eat and the energy it takes to grow the cereals - mostly coarse grains - that makes up the bulk of their diet.

One of the world’s 18.5 billion chickens. That’s a lot of feed. Image: Roslin

One of the world's 18.5Bn chickens. That's a lot of feed.
Image: Roslin

Hence, researchers at The Roslin Institute, Edinburgh, an Institute of BBSRC, are aiming to extract small efficiency gains in how poultry metabolises grains which could boost production and lead to massive energy and monetary savings in the long term because of the huge numbers of animals involved.

Bird of a feather flock together

The three-year £1.65M project, funded by BBSRC through the Defra-administered Sustainable Livestock Production LINK programme, combines Roslin with industry partners Aviagen, a UK-based company and one of the world's leading producers of broiler (meat) chicken breeding lines, and Affymetrix, which specialises in developing tools for genomics and genetic sequencing.

Together, the three partners will develop new genetic sequencing platforms to accelerate the development of breeds that utilise feed more efficiently - how much feed you need to make a given portion of chicken meat.

To do that, Roslin scientists will label different chickens with a dense array of markers so that beneficial traits can be spotted and fast-tracked into production, a process called 'genome selection'. "It is based on the simple idea that with a sufficient number of genetic markers covering the entire genome, we can account for all the genetic variation in any trait," says Professor Dave Burt, Group Leader at Roslin and coordinator of the LINK project. "So from the genomes of animals in a test population with known characteristics we can learn to recognise similar animals in the next generation."

The project will sequence chicken DNA on a massive scale. Image: Abizar

The project will sequence chicken DNA on a massive scale.
Image: Abizar

His team will genotype 1000s of animals with more than 500,000 genetic markers (SNPs, or single nucleotide polymorphisms) for known characteristics such as growth rate and feed metabolism which have been identified through sequencing of the chicken genome (ref 2). These 'test' populations will then be analysed using complex computational techniques so that useful traits related to feed efficiency can be identified in the next generation of conventionally bred chickens from their genomes alone.

"This will transform animal breeding and provide a practical demonstration of genome selection," says Burt. "Our plan is to produce a dense marker map of 500-750,000 markers based on the complete sequences of more than 20 broiler and layer lines."

Burt says that the density of markers allows them to test the genetic effect of the entire genome on specific traits and that the approach is general and therefore applicable to all livestock and domestic species.

Not a poultry matter

The improvements in feed efficiency in the Aviagen chickens could be as much as 20-40%. Even at the lower end of this prediction it could lead to large savings in feed costs predicted to amount to 86,000 tonnes of feed, more than £10M per year, by 2025. If feeding efficiency were improved by 20% worldwide, the saving could be 2.85M tonnes and more than £350M per year.

Roslin scientists will work from a new £60M building from March 2011. Image: Roslin

Roslin scientists will work from a new £60M building from March 2011.
Image: Roslin

Improving feed efficiency also saves energy, thus enhancing aspects of food security whilst reducing agriculture's carbon footprint. The UK saving after 15 years is estimated to be 288,000 tonnes of CO2 equivalents per year and about 700 tonnes per year less ammonia. Because these two compounds also have prices, an additional saving of more than £8M can be made each year.

After development, the 500,000 marker chip will be made available to other academics and animal breeders through Affymetrix, whose high-speed low-cost genotyping tools are capable of genotyping 500-750,000 SNPs in more than 200 animals per day and make genome selection projects such as this a reality.

The project was assisted by the Technology Strategy Board's Biosciences Knowledge Transfer Network, which helped Roslin and Aviagen secure the funding for the project.

References

1. http://faostat.fao.org/site/573/default.aspx#ancor

2. Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution