@article{oai:kindai.repo.nii.ac.jp:00005143,
 author = {犬塚,  澄雄 and 大石,  武士},
 issue = {8},
 journal = {近畿大学農学部紀要, Memoirs of the Faculty of Agriculture of Kinki University},
 month = {Jan},
 note = {[Author abstract]Two experiments were conducted to determine the effects of the naturally decreasing day-lengths during the fall months on egg yolk colour and serum xanthophyll content in laying hens. Two years old White Leghorn hens were used in these experiments. They were kept in uncontrolled environment which consisted of individual laying cages without artificial light and were fed a commercial all-mash laying ration as a basal diet. All eggs that were broken out were scored using Roche yolk colour fan and the serum xanthophyll content was determined by the method of Wilson. A declines in egg production and feed consumption were observed as the fall months went by, and then egg production paused steadily almost to the end of the experimental period. It was observed during this period that hens which lay at a heigh rate of production deposit fewer xanthophyll in the blood serum than hens lay at a low rate. About pause in laying the yolk colours were still different but the depth decreased somewhat, while the serum xanthophyll content increased relatively at high level. The great increase in serum xanthophyll content was when the hens paused in laying. This increase occurred because of dietary xanthophyll that could not be deposited in the egg yolk.[著者抄録]夏季孵化のWhlte Leghorn種成鶏(2年鶏)を供試し、中秋より晩秋の6週間(実験I)、および春季孵化の同種(2年鶏)を供試し、初秋より産卵休止に至るまでの9週間(実験II)をそれぞれ実験期間として、自然日長の短日期における卵黄の色調および血清中のキサントフィル含量におよほす影響、ならびにそれらに影響する二、三の要因について検討した結果を要約すれば、つぎのとおりである。短日期に入ると、産卵率および飼料摂取量はともに著しく低下し、産卵休止(換羽)の現象が認められ、血清中のキサントフィル含量は産卵率50%以下に達すると急速に増加した。しかし、その後さらに産卵率が低下しても、キサントフィル含量は停滞気味であった。個体レベルでは、産卵休止にともない体重は著しく増体し、飼料摂取量は逆に10%程度の減少が認められた。この結果は個体によって異なる傾向が強い。卵黄の色調は休産状況に近づくに従いややうすい傾向を示した。平均の色調度は9.57-9.00程度である。産卵率の低下および飼料摂取量の両要因の複合した形での、色調への影響は認められなかった。血清中のキサントフィル含量は産卵状況の良好な場合には低い値であったが、産卵休止前後には著しく増加し、卵黄への移行が阻止された現象であると推測された。, application/pdf},
 pages = {7--14},
 title = {自然日長の短縮が卵黄の色調および血清キサントフィル含量におよぼす影響},
 year = {1975},
 yomi = {イヌヅカ, スミオ and オオイシ, タケシ}
}