Teun van de Braak is a laying hen geneticist with Hendrix Genetics in The Netherlands. As a recent guest lecturer at the University of Guelph, van de Braak described the road taken to developing our modern version of the laying hen. He also glimpsed to the future.
A bit of history
Chickens were originally domesticated for cock fighting, said van de Braak. We actually went wrong right at the beginning by selecting for aggression. For the most part their breeding was more about ornamentation than production, with chateau owners claiming bragging rights about having the most beautiful birds. A lot of diversity was achieved during this time but egg production remained a seasonal consideration.
Under the influence of Mendelian genetic theories from the mid-1800s, scientists at the turn of the century were taking new interest in poultry breeding, exploring inheritance characteristics of traits such as feather colouring, comb shape and skeletal defects. Poultry breeding at this time was focused on exploring the process of heredity. In the 1930s, as beauty began to separate from utility, poultry breeding pioneers such as Don Shaver and JJ Warren began developing today’s production lines.
After World War II there was a huge shift from small scale, multi-species farming to specialized, one-species farms. There were big changes to housing as well, which signaled the start of modern production. These changes affected all livestock with a rapid shift from dual-purpose to single purpose breeds.
In the past relatively short 50 years we have seen an 11 kg turkey now take half the time to produce as it did in 1960. Laying hens that used to give 230 brown eggs per hen in 1960 now give 410 eggs, producing 5,000 eggs per ton of feed then compared to 9,500 eggs per ton of feed now. Better housing systems, better management and better genetics have all played a role.
Phenotype vs. genotype
On the genetics side, this increase in efficiency and meat production has mainly been done with phenotypic selection, said van de Braak, where what you see is what you get. We’ve used the diversity available with natural selection to develop purpose-created birds. But when you are selecting based on phenotype – basically on looks and performance records – how do you know you’re producing the best bird? Genetic advances rely on comparing production between generations using information from progeny records. That takes time.
In the 1960s, breeding was done by obvious selection of traits – the rooster looked nice and the hen laid a measurable number of eggs. Lots of family information was available. By the 1980s, geneticists had estimated breeding values known as BLUP (Best Linear Unbiased Prediction) as a tool, utilizing the power of computers to analyze data.
By the turn of the century, genomic selection was able to offer a better insight into the genetic potential of a bird’s DNA profile, supporting breeding decisions especially where two or more lines may have similar genetics and appearance.
If you’re breeding with proven sires it takes the length of the production cycle to measure outcomes. But now with genomics – the sequencing and analysis of the genetics of the bird – that wait time has been greatly decreased and more accurate selection decisions can be made. Genomics also allows the verification of parentage, reducing inevitable human error by using the right eggs.
At some point the birds are at the full limit of their production – the genetics are at a maximum. To make gains it is necessary to have variation, but at a certain point there is little variation left. With laying hens, for example, the only way to get more eggs now is to increase the length of the laying cycle. Breeding goals are changing for laying hens from an emphasis on production and parent stock efficiency to product quality and, more recently, to the health and welfare of the bird. In that regard, van de Braak sees huge potential for the future.
Over the last 30 years, the trend of changing cages to aviaries in Europe has led to a demand for different birds. Breeding for caged birds allowed a focus on efficiency of production, using minimal input for maximum output. But you cannot put a bird that was bred to be kept in cage conditions and expect it to be able to go outside. In alternative housing systems, the birds may require more energy for maintenance, needing to be a little more robust and eat more. “It’s all there,” van de Braak said. “It’s all in their DNA.” Hendrix keeps many pure lines to ensure that there is a lot of genetic variation from which to choose. If there was only one trait to change, the progress would be fast. But their breeding program needs to take 35 traits or more into account and many of those traits are negatively correlated.
Breeding for animal welfare
When breeding for animal welfare, geneticists need to ask, what are the risks of going in a certain direction? How fast should they go? How do the selected traits balance with economic traits? How will phenotypes be measured? How will breeding goals be defined? Hendrix’s “social breeding program” has brought continued progress to their lines. The goal is to identify friendly families with good production and monitor their reaction to the stresses of production such as higher light intensity. To select and mate those families will result in hens with improved feather cover and less mortalities.
In layers, the selection pressure has been increased for these social traits and others. Feather cover tells you something about feather pecking, van de Braak explained. It is also an indicator of stress since birds tend to jump on top of each other if they are stressed or scared, causing a lot of feather damage. Mortality due to cannibalism is higher now with birds being kept with intact beaks compared to flocks that previously underwent beak treatment. Other breeding goals now include selection for E. coli resistance, reduced keel bone damage and improved gut health.
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As Hendrix-Genetics looks to the future, the challenge remains, how to feed the world while maintaining respect for the animals? Van de Braak says they are shifting towards group housing systems at their research and development facilities, which means finding new ways of collecting data on individual birds.
The company is also maintaining a large gene pool to ensure genetic diversity. At times it goes back to developing traditional poultry that includes coloured turkeys and more efficient dual-purpose chickens like the ISA Dual, which provides a two kg male at 10 weeks of age and 250 eggs at 70 weeks, mostly for niche markets and developing countries.
There can be a downside to big gains too, van de Braak said. “It wasn’t always hallelujah.” Broiler birds grow too fast and have become more sensitive to Marek’s disease, while the progress that has created efficient superbirds of one sex has resulted in the other sex not being as useful: what is their fate? These are concerns we must address in our breeding programs, van de Braak said.
Consolidation is changing the landscape of the poultry breeding world. There used to be hundreds of breeding companies. Nowadays, Hendrix Genetics is one of only two big players in the world – the other company is the Erich Wesjohann Group.
Hendrix Genetics is one of the world’s largest suppliers of laying hens and turkeys, supplying half of the layer market and 55 to 60 per cent of the world turkey stocks.
“On the one hand, it might have led to less genetic diversity – with all the consolidation (mergers and acquisitions), some of the experimental pure lines are no longer there,” van de Braak said. “On the other hand, combining the genetic lines of the different breeding programs gave opportunities to produce new hybrids.” Some of the new three or four-way hybrid crosses have provided better field results compared to the old crosses. This has led to improved productivity, egg quality and health and welfare in commercial birds.
He pointed out that some of the pure lines were not lost – a few have been donated as heritage lines to universities and research institutes. At the University of Guelph, for example, Don Shaver’s flocks continue to offer their heritage genes at the Arkell Research Station near Guelph, Ont. Initially, in 2003, the heritage lines were maintained by the research station staff under directives from Don Shaver. Soon after, Grégoy Bédécarrats, a professor at the University of Guelph, began supervising breeding and implementing care guidelines.
“Due to budgetary constraints, we needed to find a solution to spread the workload of breeding beyond farm staff,” the professor explained. With the help of Don Shaver, they formed the student-run University of Guelph Poultry Club, which has provided a tremendous opportunity to expose students to poultry science and reintroduce practical application and hands-on training. Through this initiative, the responsibility of care has been progressively transferred to the club, including duties of collection and analyses of egg production and quality data, selection of hens to be used for breeding, performing artificial insemination and participation in the hatch. The University of Guelph poultry club is now in charge of maintaining these birds as pure lines as close to what they were when donated.
To further enhance this experiential learning, Bédécarrats teamed up with the Poultry Industry Council (PIC) to develop a certificate on artificial insemination that would be recognized by the industry, giving club members the opportunity to gain practical knowledge relevant to future employment.
However, the farm staff still performs day-to-day maintenance of these birds, requiring labour, barn space and resources in competition with a full slate of other research activities. “The hope and intent of keeping these lines was that they would be used for research and education,” Bédécarrats said. “Although we cover the education part, little research has been done.”
He said that these genetics could serve to recreate a viable commercial population in the case of a catastrophic event such as a large influenza outbreak, and in a sense they represent Canadian poultry genetic heritage. “The genetics in these birds is very valuable, although not at a commercial level. So the issue is, who will pay to keep the lines alive?”