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Techniques for Preserving and Improving Long-crowing Chickens in Japan: A Case Study of the Tomaru in Niigata Prefecture and Koeyoshi in Akita Prefecture
Get PDFThis study presents a new interpretative framework for understanding how the long-crowing abilities of Tomaru and Koeyoshi chickens have been preserved through breeding and rearing techniques in Japan. Studies on long-crowing chickens have documented breed characteristics, examined their relationships with other breeds, and investigated the conservation management of their genes. Although these studies have highlighted past breeding techniques, they typically provide only simple descriptions and lack a common interpretative framework. This work reports breeding and rearing approaches used for two Japanese long-crowing chicken breeds: the Tomaru in Niigata Prefecture and Koeyoshi in Akita Prefecture. Each breed is maintained by a small number of breeders based on a small population. Hence, recording this information is particularly urgent. This study first describes breeders’ practices and goals regarding parent selection, mating, egg laying, hatching, brood rearing, young bird selection, and crowing training. It then demonstrates that breeders in both prefectures emphasize selecting and breeding parent birds with superior long-crowing ability to preserve these traits. The long-crowing trait is difficult to improve through reward-based training, such as using feed as reinforcement. Then, based on the findings, an interpretative framework is applied to understand the application of these approaches for preserving and improving long-crowing in the Tomaru and Koeyoshi breeds. The careful adjustment of these techniques has allowed breeders to balance two opposing goals: preserving desired breed characteristics and avoiding negative inbreeding effects. This interpretive framework may be applied to other avian breeding techniques.本論文は，日本鶏のなかで長鳴きの特性をもつ蜀鶏と声良鶏を対象に，双方の繁殖・飼育技術を記述したうえで，長鳴性を保持させる技術を理解するための解釈枠組みを新たに提示するものである。日本の長鳴き鶏に関しては，その品種特性を紹介したものや飼育の技術を記述したもの，他品種との類縁関係を検討したもの，遺伝子の保存管理を検討したものなどがある。しかし，先行の研究ではたんに事例を祖述しただけのものが多く，一連の飼育技術を広く捉えるための枠組みを示したものはない。そこで筆者は日本の長鳴き鶏のなかで飼育者と飼育羽数が少なく，記録の緊急性が高い新潟県蜀鶏と秋田県声良鶏を対象に調査を進めた。本論文ではまず双方の飼育現場において親鳥の選抜から交配，産卵，孵化，育雛，長鳴きの訓練にいたる繁殖・飼育技術を記述した。これら一連の記述を通して，いずれの現場でも品種特性の保持と改良には優れた特性をもつ親鳥の選抜と交配がとりわけ重視されていることが分かった。ニワトリがもつ長鳴性は餌を強化子とした報酬訓練による改良が難しいためである。これらの成果を踏まえ，本論文では品種特性の保持と近交弱勢の回避という二つの志向性からなる解釈枠組みを新たに提示し，飼育者たちが個々の局面に応じて双方のバランスを調整しながら長鳴き鶏の飼育を続けていることを明らかにした。最後に，ここで新たに示した枠組みの展開可能性についても言及した。1 Introduction
1.1 Background and Purpose
1.2 Survey Methods
2 Targeted Long-crowing Chickens
2.1 Description of Japanese Chickens and the Development of Long-crowing Chicken Breeds in Japan
2.2 The Tomaru Breed
2.3 The Koeyoshi Breed
3 Tomaru Breeding and Rearing Techniques Practiced in Niigata Prefecture
3.1 Breeding and Rearing Techniques
3.2 Efforts to Preserve Breed Characteristics
4 Koeyoshi Breeding and Rearing Techniques in Akita Prefecture
4.1 Breeding and Rearing Techniques
4.2 Efforts to Preserve Breed Characteristics
5 Discussion
5.1 Key Techniques Common at Tomaru and Koeyoshi Breeding Sites
5.2 Techniques for Improving the Longcrowing Trait
5.3 Balancing the Preservation of Breed Characteristics against Negative Inbreeding Effects
6 ConclusionAjournal articl
