Points of contact between zoos and poultry science
Tsukuba University College of Biological Sciences
Atsushi Tajima
Transitions in the zoo
Tiergarten Schönbrunn in Vienna, which is said to be the oldest surviving modern zoo, was built in 1752 by the Holy Roman Emperor Francis I as the imperial ménagerie next to Schönbrunn Palace. This term ménagerie is derived from the Latin term manere or the Old French term mainer, which signify “to stay”, and the context behind this term was that of a facility for displaying wild animals that were captured by aristocrats in order to flaunt their wealth and power.
In Europe, after becoming economically prosperous following the Industrial Revolution, zoos and botanical gardens were established one after another in order to exhibit the various flora and fauna that were collected worldwide during the Age of Discovery from the 15th to 17th centuries. For example, in 1793, during the French Revolution (1789–1795), a zoo was established in Paris as the first national institution for “zoological studies” in Le Jardin Des Plantes de Paris, which was under the jurisdiction of the Muséum national d’histoire naturelle.
Subsequently, in 1826, the London Zoological Society was founded, and in 1828, the Zoological Gardens of the London Zoological Society (short form, “Zoo”) was opened as an animal garden for members that was located in a part of the Regent’s Park, which was awarded to the Royal Family; by 1847, the Zoo was opened to the public in order to resolve its financial problems. The prospectus for the Zoo’s establishment stated that “it plays an important role in the study and education of the characteristics and habits of animals, and the collected animals would be subjects not of spectacle but of scientific research” (Murata, 2019). Thus, the menagerie, which was initially established by aristocrats in order to flaunt their wealth and power, eventually transformed into a zoo with academic significance.
Behind these movements of collecting and displaying flora and fauna from this academic perspective was the strong drive of wanting to learn the full picture of the perfect natural system (Systema naturae) that was created by the omniscient and omnipotent God, which had been a long-held desire of the Christians since the Reformation.
Meanwhile, Ueno Zoo, which was the first zoo in Japan, opened in 1882 (Meiji 15) as an annex of the museum under the jurisdiction of the Ministry of Agriculture and Commerce that was built in Ueno Park. Afterwards, in 1886 (Meiji 19), its jurisdiction was transferred to the Imperial Household Ministry, and in 1924 (Taisho 13), the zoo was given to (then) Tokyo City in commemoration of the marriage of His Imperial Highness the Crown Prince (Emperor Showa). The registered name as a business establishment after this event was the “Ueno Zoo”.
Until the mid-20th century, the primary functions of zoos were exhibitions and wildlife research, but endangered species began to emerge as a result of the gradual increase in the economic value of rare wildlife. In response, on March 3, 1973, the Convention on International Trade in Endangered Species of Wild Fauna and Flora, commonly known as the Washington Convention, was adopted in Washington, D.C., United States of America, coming into effect on July 1, 1975. This was a convention with the aim of protecting certain species of wild flora and fauna that form an irreplaceable part of nature from being overused in international trade, with Japan becoming a signatory country on November 4, 1980.
Prior to this, Japan stipulated the Act on Regulation of Transfers, etc. of Special Birds (Act No. 49 of 1972) in 1972 and the Act on Regulation, etc. of Transfers of Endangered Wild Fauna and Flora (Act No. 58 of 1987) in 1987, though these two acts were abolished in response to the enforcement of the Act on Conservation of Endangered Species of Wild Fauna and Flora (Act No. 75 of 1993, commonly known as the Species Conservation Act) on April 1, 1993.
With the signing of the Washington Convention, the new function of genetic resource conservation was added to the zoos’ existing functions of exhibitions and academic research. Zoos must function as wildlife conservation facilities in order to maintain their existing genetic resources following the restrictions on the international trade of wild animals. Furthermore, Tokyo formulated the Zoostock Plan in 1989, promoting breeding by concentrating breeding activities in a single metropolitan zoo for each species that is protected by domestic and international laws or species that require protection due to decreased numbers of wild individuals. Currently, Tokyo is promoting the Second Zoostock Plan that was formulated in FY2018, in light of changes in the circumstances surrounding metropolitan zoos. These initiatives serve as the backdrop to the captive breeding attempts of wild animals, as introduced in this book.
Transitions in poultry science
Unlike zoos, which keep wild animals in captivity and manage them, poultry science is a field that provides education and research on the use and improvement of domesticated birds, and it is the only specialized field in animal husbandry that deals with livestock other than mammals, with the objective of improving the productivity and quality of meat, eggs, feathers, and other related products that are essential for human life. Today, poultry is the main livestock along with cattle and pigs that constitutes livestock science. However, though there are differing theories regarding the domestication of birds, it is said to have begun 3,000 to 6,000 years ago, and it can be said that its domestication was relatively recent when compared to the domestication of cattle and pigs, which were domesticated about 8,000 to 10,000 years ago.
Additionally, the background, morphology, and physiology associated with this type of domestication is quite different from those of mammals because the geographic area from where birds were domesticated is Southeast Asia, which is geographically distant from West Asia, where cattle, sheep, goats, and pigs were mainly domesticated; and because birds are animals that are adaptively radiated to fly in the sky. Therefore, poultry have different uses as livestock. For example, mammalian livestock have been mainly used for meat, work, and dairy. Meanwhile, the rooster has a certain mystique with its high-pitched crowing and viewed as sacred, acting as a symbol for the end of the terrifying dark night and the announcement of the dawn, and being used in cockfighting as part of rituals (Okamoto, 2001).
It can also be said that the chicken in Japan holds a unique status that is different from that of other domesticated animals. This can be seen in the painting of Ajisai Sokei-zu (“Hydrangeas and Pair of Chickens”) by the 18th-century genius painter Ito Jakuchu, in the use of chickens as a subject in Japanese classical performing arts, such as Keimyo (“Chicken cat”) in Zatsumono Kyogen and Niwatorimuko (“Chicken groom”) in Mukomono Kyogen. or when Amaterasu Okami became angry at Susanoo-no-Mikoto’s actions in Takamagahara and hid herself in Ama-no-Iwato, resulting in darkness across the world, and having Nagataki-no-Tori crow out.
Meanwhile, the efficient production of poultry that has been converted to industrial animals involves the development of photoperiod management technology for the year-long spawning of birds, which are naturally seasonal breeders; artificial insemination technology for efficiently obtaining fertilized eggs; incubators for hatching fertilized eggs in an artificial environment, and basic technology and equipment such as artificial brooding devices that heat and raise hatched chicks.
Among these developments, the incubator, which holds the key to the poultry industry, was developed when Lyman Byce, a 26-year-old medical student who arrived to Petaluma, California, from Canada for medical treatment in 1878, learned that there was a large demand for fresh eggs in the neighboring major city of San Francisco (Heig, 1982).
At the time, existing incubators that used the heat of fermentation could not maintain a temperature of 38 °C for three weeks, and the hatching rate was low and unstable. During that period, the form of transportation of cargo such as agricultural products that were shipped from Petaluma had begun to shift from steam engines to electric engines, so Byce conceived the idea of using an electric heater and worked to develop an electric incubator with Isaac Dias, a young local dentist. As a result, they successfully developed the incubator in September 1879, where the two observed chicks breaking through their shells and coming out via a transparent glass door that was attached to the incubator (Heig, 1982). Afterwards, Byce succeeded in incubating 95% of the 400 eggs in the incubator in a demonstration in 1882, obtaining a patent for the incubator on September 15, 1914 (Byce, 1914) (Fig. 1).
Fig. 1. Incubator patent acquired by Lyman Byce
The development of the wire cage in Petaluma around the same time dramatically facilitated fecal removal and disease management, and brooding technologies began to develop as a result of the development of the chick hatchery by Christopher Nisson. These series of technological developments made Petaluma the center of poultry farming in the United States. At the same time, it can be said that modern poultry farming has since become an electricity-dependent industry.
The direct ancestor of the domesticated chicken (Gallus gallus domesticus) has been thought to be the red junglefowl (Gallus gallus) among the four known wild chickens. This red junglefowl’s body, habit of vocalizing in the early morning, and its inability to fly in the sky are very similar to the characteristics of present-day chickens.
However, a series of recently conducted genome analyses of the two chickens indicated that the direct ancestor of the chicken may have been the result of mating of not just the red junglefowl but another wild chicken called the grey junglefowl (Gallus sonneratii) (Eriksson et al., 2008). It is extremely difficult to accurately identify the origins of chicken domestication, but there is a need to further this discussion with the help of advanced and diversified analytical methods.
Meanwhile, when looking at birds in general, recent research has led to the prevailing theory that birds are a direct descendant of theropod dinosaurs that survived the K-Pg boundary mass extinction event (ICS, 2012) that occurred 66 million years ago (Prum, 2008). These findings impact taxonomy, and though birds are described as class Aves in the phylogenetic nomenclature of Linnaeus, they are now classified in the clade Theropoda in present-day phylogenetic nomenclature (NCBI, 2021). In addition, Ruggiero et al. (2015) organized the classification system for all organisms, placing reptiles and birds under class Reptilia and setting the five subclasses of Aves, Crocodylomorpha, Testudinata, Squamata, and Rhynchocephalia. There has also been discussion over the Japanese translations of clade names in clade classification of dinosaurs (Tomida et al., 2020).
The extinction rates of 210 families of vertebrates in this K-Pg boundary mass extinction event were reported, with pterosaurs (two families), dinosaurs (21 families), and plesiosaurs (three families) among reptiles becoming completely extinct (100%); meanwhile, nine out of 12 families (75%) went extinct among birds, and five out of 22 families (23%) went extinct among mammals (Takahashi and Goto, 2010). In other words, the existing birds today are descendants of four families of birds that survived the K-Pg boundary mass extinction event, so birds are considered to occupy an important position when studying the evolution of the vertebrate phylum.
Points of contact between zoos and poultry science
The emergence of next-generation sequencers has allowed for genome analysis and gene expression analysis to be conducted in a short period of time. As a result, the genomic information of various birds, including existing species and fossils, can be analyzed, which has led to considerable discussion over the evolution of birds, their speciation, and domestication. However, it is ideal to add information on the physiology and ecology that is unique to these species when creating a more accurate phylogenetic tree. In that sense, valuable information is provided from wild animals in zoos, where the genetic resources are kept alive, and from domesticated chickens and quails, which can be said to be experimental animals among birds.
Meanwhile, according to the IUCN Red List of Threatened Species (2020), there are 11,158 currently existing bird species, constituting 15.3% of the 72,000 currently existing vertebrate species, but 1,481 (12.3%) bird species are endangered (IUCN, 2020). Even in Japan, a total of 154 bird species (including local endangered populations) have been designated as endangered species (Ministry of the Environment of Japan Red Data, 2020). The fact that there are animals on the verge of extinction due to large changes in the global environment as a result of human activities is a major problem. There is a need for humans to modify their activities to conserve the global environment, and at the same time, protect animals that otherwise do not need to go extinct and to make every effort to protect these genetic resources.
Among chickens, sperm cryopreservation technology and primordial germ cell preservation / transplantation technology have become established, and technologies that can preserve and restore the genetic resources of birds at the cellular level have been developed (Tajima, 2013). Although there are limited examples, the successful production of a germline chimera between different species has been reported (Li et al., 2002; Liu et al., 2012); therefore it is considered that there is enough potential for these technologies to be applied to the conservation and proliferation of genetic resources in endangered rare wild birds.
Complementary cooperation between zoos and poultry science in the future will increase the number of contact points. As such points increase, they will become lines and surfaces, and as surfaces accumulate, they will become three-dimensional, and in the same vein, we hope that synergistic effects and super-dominant effects will be achieved in a wide range of fields, from the basic to the applied sectors.
Acknowledgments
We would like to express our deep gratitude to Kazuhisa Honda (Kobe University), Tomohiro Sasanami (Shizuoka University), and Mitsuru Naito (formerly National Institute of Agrobiological Sciences) for their valuable comments when writing this article.
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