「Endeavoring to develop high-performance chicken breeds in Japan to improve food security」
Japan’s self-sufficiency rate in chicken eggs is generally believed high—about 95% according to the Ministry of Agriculture, Forestry and Fisheries. Professor Tsudzuki, however, presents an entirely different picture. “It is actually only 6% or so. As for chicken meat, our self-sufficiency rate is said to be about 70%. In reality, it is less than 2%. In other words, 98% of chicken meat is imported.” To explain these disparities in numbers, let’s look into the lineage of utility chickens distributed in Japan.
    From chicken eggs sold in retail stores, we can trace back the lineage of utility chickens to ‘commercial chickens’ kept at chicken farms, then to ‘parent stock’, ‘grandparent stock’, ‘great-grandparent stock’, and finally to ‘pedigree stock’. Professor Tsudzuki says it is mainly the parent stock imported as chicks that actually produce chicken meat and eggs in our country. That explains why our self-sufficiency rates in chicken meat and eggs in the real sense are those shown above.
     “So if avian influenza breaks out, for example, chicken imports will stop instantly. Besides, global warming and other global climate changes are feared to cause other diseases or reduce the productivity of American and European breeds. Since chicken meat and eggs are one of our important protein sources, we will be in big trouble if we remain heavily dependent on imported chickens. That is why we must develop high-quality pedigree stock here in Japan,” says Professor Tsudzuki.
     Japan has many native chicken breeds, but their egg and meat productivity is not as high as that of improved breeds. To address the lack of high-performance native chickens, Professor Tsuzuki and his team are working to establish new domestic breeds. According to Professor Tsudzuki, “Conventional breeding techniques lack accuracy and speed. In the case of eggs, for example, we typically use a ‘selective breeding’ technique with which we pick out hens with higher egg productivity from every generation. However, this process takes many generations of chickens and 30–40 years of efforts to achieve the intended results. Meanwhile, this method also lacks accuracy because the stock being bred can be affected by environmental factors such as temperature and feedstuff during the intervening period. That is why we decided it best to identify desirable genes by eliminating all possible environmental effects.

 「The one and only university in Japan engaged in QTL analysis to locate desirable loci」
What makes his endeavor possible is the QTL analysis introduced in the 1990s. For the past 15–16 years, Professor Tsuzuki has conducted research in which he uses this method to identify loci that control chickens’ productivity such as egg-laying rates and meat productivity. His team is the only group in Japan that is engaged in this kind of research project.
    “QTL analysis uses DNA data to find out what kinds of genes are in what position of the chromosome,” says the professor. “Based on these analysis results, we are trying to carry out ‘DNA breeding’ by means of ‘marker assisted selection.’”
    However, QTL analysis can reveal only the locations of genes, called “loci.” If the analysis procedures are refined even further in the future, however, the QTL method will be able to show not only the location but also the nature of genes. Using such genetic information, it will become possible to improve specific traits of animals in a more accurate and speedy manner.

    “I myself have discovered about 700 loci since I started my research using QTL analysis in 1997,” says Professor Tsuzuki. “Some of them concern egg-laying rates and others body weight. Typically, chickens’ weight changes are checked up until about 7 weeks after birth. But here, we check chickens’ weight until they are 64 weeks. Specifically, we weigh them once a week until they become 20 weeks and after that once a month. No other place in the world monitors chicken weight for such a long period of time. We have also identified the loci that concern the size and weight of eggs as well as the color and size of yolks. All of this suggests that our research efforts have produced substantial academic results. What has greatly helped us make these accomplishments is that we have used Japanese native chickens for our research.”
    Although it is technically possible to improve chicken breeds based on the results obtained so far, the lack of financial and human resources delays such endeavor. Meanwhile, challenges remain in revealing the nature of relevant genes and improving chicken breeds by using such genetic information. Graduate students, come and join Professor Tsudzuki’s lab!
「Unending quest for developing high-performance utility chicken breeds and the role as the nation’s leading Japanese chicken research institute」

In the QTL analysis, two different breeds are crossed to produce their children and grandchildren. Then, DNAs of the three generations of chickens are analyzed all at once. And if useful gene loci are identified, there are two options—either to transfer relevant genes to Japanese breeds or to high-performance breeds of European or American descent that are kept in Japan. Because the former procedure is time-consuming, the latter, more efficient procedure tends to be chosen.
    “If only we have enough money, we will be able to develop marketable breeds in 5–10 years. In just 20 years after the start of the breed improvement effort, we should be able to establish pedigree stock. And if we use next-generation sequencing methods, we can speed up the breeding process even further,” comments Professor Tsudzuki.
    While engaged in these research activities, Professor Tsudzuki studies genetic diversity of chickens. Since 2010, he has also served as director of the Japanese Avian Bioresource Project Research Center. The center keeps about 4,000 individual chickens and quails on the HU campus, including as many as 120 kinds of chickens.
    Professor Tsudzuki says, “Our center aims to develop high-quality domestic grandparent stock, while preserving Japanese indigenous breeds, maintaining genetic diversity, and passing the Japanese chicken culture on to future generations. The research center is open to the public and visitors are always welcome. I would like to see as many people as possible realize the wonderful qualities of native Japanese chickens.”
Masaoki Tsudzuki
Animal Breeding and Genetics Laboratory
Hiroshima University School of Applied Biological Science
1983: Graduated from Department of Animal Science, School of Agriculture, Nagoya University

1988: Completed the doctoral degree program at the Graduate School of Agricultural Sciences, Nagoya University
April 1, 1989 – March 31, 1990: Fellow, Research Fellowship for Young Scientists, Japan Society for the Promotion of Science
April 1, 1990 – March 31, 1996: Assistant Professor, Laboratory of Experimental Animal Science, Department of Veterinary Science, School of Agriculture, Osaka Prefecture University
April 1, 1996 – March 31, 2002: Associate Professor, Department of Applied Biological Science, School of Applied Biological Science, Hiroshima University
April 1, 2002 – September 30, 2004: Associate Professor, Graduate School of Biosphere Science, Hiroshima University
October 1, 2004 – : Professor, School of Applied Biological Science, Hiroshima University
April 1, 2006 – : Professor, Graduate School for International Development and Cooperation, Hiroshima University (concurrent post with above)

Posted on May 22, 2013