Non-hereditary crooked beaks in poultry

家禽における非遺伝的畸形嘴について

Watanabe Moriyuki

広島大学水畜産学部紀要

Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University

　本実験においては非遺伝的畸形嘴と思われる三例に遭遇した.その一つは大阪アヒルにおいて認められ，他の二つはニワトリのembryo において認められた.
　大阪アヒルは孵卵開始後25日目に約3時間の停電に遭遇した卵から28 日目に孵化したもので，約1年間育成しその畸形嘴の発育状態および精液の一般性状について観察された.畸形嘴の度合は日数の経過と共に著明となったが，精液の性状については何等異常は認められなかった.
　ニワトワにおける畸形嘴の一例は孵卵開始後9日目に約4時間の停電に遭遇した卵を瞬卵15 日日に破殻したembryo において認められたものであり，他の一例は破殻3日前から1日6回，約10分間孵卵温度を低下した卵を孵卵10日目に破殻したembryo において認められたものである.前者は一方の無眼球症を伴なった上嘴畸形を示し，後者は一方の小眼球症を伴なった上嘴畸形を示した.
　これらの眼球および嘴の畸形は共に好ましからざる環境要因によって誘起されるものと思われるが，直接との非遺伝的畸形に包含されている因子ならびにその機構についてはよくわからない.

Three examples suggestive of non-genetic deformed beaks were found in the present experiments. One was found in an Osaka duck and two were found in chicken embryos.

The duck was hatched on the 28th day from an egg whose incubation was suspended for about three hours on the 25th day of incubation by interrpution of electric current. The duckling was raised for one year and the developmental condition of its deformed beak was observed. Its semen was also examined. The degree of the crooked beak became marked with time, but no abnormality was found in the general properties of the semen.

The other two were found in chick embryos. One was obtained from an egg whose incubation was suspended for about four hours on the 9th day of incubation by interruption of electric current. The shell was cracked on the 15th day of incubation.
The other was obtained from an egg whose incubation temperature was lowered six times a day for ten minutes for three days before the shell was cracked on the 10th day of incubation. The former showed the upper beak to be deformed and accompanied by unilateral anophthalmia, and the latter showed the upper beak to be deformed and accompanied by unilateral microphthalmia.

It is assumed that the deformity of the eye and beak may be induced by the same unfavourable environmental factor, but the factors and mechanism immediately involved in the non-heredetary abnormality are not known.

Zoology [ 480 ]

eng

広島大学水畜産学部

[ISSN] 0440-8756

[NCID] AN00213563