豚の性成熟期に関する研究,特に中国豚の早熟性について  [in Japanese] Studies on the Age of Sexual Maturity of Swine with Special Reference to the Early Maturity of Chinese Breed  [in Japanese]

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Abstract

豚の性成熟期を明らかにするために, 改良種4種 (M. W., B, L. W., P.) 計528頭と中国種 (C.) 84頭について生殖器系の発育を形態学的, 組織学的, 生理学的に研究調査すると同時に, 射精能力, 初発情 (初排卵), 受胎能力等について観察・調査を行った。<br><b>A. 雄豚の性成熟期について</b>: 1) 精巣, 精巣上体, その他副生殖腺の重量発育および比体重値は改良種では4~8ヵ月齢において増大が著しいが, 中国種では2~5ヵ月齢頃から発育が著しく, きわめて早熟である。2) 陰茎の遊離期は, 改良種では生後114~248日, 体重24.0~65.0kg前後であるが, 中国種では生後55~100日, 体重4.6~16.0kgできわめて早い。3) 精巣の組織学的所見において, 精細管口径の発達は改良種では4~6ヵ月齢の間において著しく, 7~8ヵ月齢で約200μmに達するが, 中国種では2~3ヵ月齢の間において発達が著しく, 4ヵ月齢で約200μmに達する。4) 精細管内に初めて精子を認めた日齢は, 改良種では大体生後120日, 体重27~35kg前後であったが, 中国種では生後40日, 体重4.2kgであった。5) 精子を認める精細管数, 精巣成熟度は, 改良種では4~5ヵ月齢から増加し5~6ヵ月齢でほぼ一定するが, 中国種では2ヵ月齢頃から増数が著しく, 3ヵ月齢でほぼ一定する。6) 精巣上体尾部に初めて精子が出現する時期は, 改良種では生後120日過ぎであるが, 中国種では生後約60日できわめて早い。なお精巣上体尾部内の精子数, 精子の活力並びに生存時間および形態等の成熟も中国種は改良種に比べて約2~3ヵ月早い。7) 射精能力の発現時期は, 改良種では151~255日齢, 体重32.0~78.5kgであるが, 中国種では84~133日齢, 体重10.2~19.5kgで, きわめて早い。8) 初回射精の精液量, 精子数は中国種において少ない。<br><b>B. 雌豚の性成熟期について</b>: 1) 初発情 (初排卵) の時期は, 改良種では194~328日齢, 体重52.0~120.0kgであったが, 中国種では147~191日齢, 体重17.9~36.5kgであった。2) 中国種の初発情豚の若干例について受胎試験を行った結果, 繁殖能力は正常であり, 産子数, 妊娠期間も正常であった。<br>以上のことから中国豚 (雄, 雌) の性成熟期は改良種に比べて著しく早いことが明らかである。

The speed of sexual maturity is an important factor in the economy of swine industry and in the improvement of swine. In this report observations were made of sexual maturities of males and females of Chinese breed, which is of Asian origin, and known as a descendant of <i>Sus vittatus</i>, and has been useful for establishment of various breeds of swine. The results were compared with those of four improved breeds, originated from <i>Sus scrofa</i>. Total 528 swine (84 Chinese, 237 Middle Whites, 106 Berkshires, 66 Large Whites and 35 Poland Chinas) were used. Anatomical, histological and physiological investigations were carried out on the male reproductive organs, epididymal spermatozoa and ejaculates. In the females, age of appearance of first estrus (with ovulation) was determined.<br>The results are summarized as follows.<br>In the males:<br>1) Marked development of reproductive organs was observed during 4-8 months of age in the improved breeds, whereas it was during 2-5 months in the Chinese ones.<br>2) Detachment of the tip (<i>free part</i>) of penis occurred during 114-248 days of age and 24.0-65.0kg of body weight in the improved breeds, whereas it was during 55-100 days and 4.6-16.0kg in the Chinese ones.<br>3) Marked development of diameter of <i>seminiferous tubules</i> was observed during 4-6 months and it reached 200μm at 7-8 months of age in the improved breeds, whereas it was during 2-3 months and reached 200μm at 4 months of age in the Chinese ones.<br>4) The earliest age for the initiation of spermatogenesis was about 120 days after birth and 27-35kg of body weight in the improved breeds, whereas it was 40 days and 4.2kg of body weight in the Chinese ones.<br>5) Marked inerease of number of <i>seminiferous tubules</i> containing spermatozoa and degree of spermatogenetic activity were observed during 4-5 months and reached constant levels at 5-6 months of age in the improved breeds, whereas increase was seen from 2 months and reached constant level at 3 months of age in the Chinese ones.<br>6) First ejaculate was obtainable during 151-255 days of age and 32.0-78.5kg of body weight in the improved breeds, whereas it was during 84-133 days and 10.2-19.5kg in the Chinese ones.<br>In the females:<br>1) Age of appearance of the first estrus (with ovulation) was 194-328 days after birth and 52.0-120.0kg of body weight in the improved breeds, whereas it was 147-191 days and 17.9-36.5kg in the Chinese ones.<br>2) Some gilts, 172 days of age and 19.4-31.3kg of body weight, conceived at the first estrus and farrowed 9 (8-11) pigs in the Chinese breeds.<br>These results show that the age of sexual maturity comes much earlier in the Chinese breeds than in the improved ones.

Journal

  • Nihon Yoton Gakkaishi

    Nihon Yoton Gakkaishi 39(1), 14-32, 2002-03-10

    The Japanese Society of Swine Science

References:  21

Cited by:  1

Codes

  • NII Article ID (NAID)
    10008284517
  • NII NACSIS-CAT ID (NCID)
    AN10202971
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    0913882X
  • NDL Article ID
    6102415
  • NDL Source Classification
    ZR22(科学技術--農林水産--畜産)
  • NDL Call No.
    Z18-1082
  • Data Source
    CJP  CJPref  NDL  J-STAGE  JASI 
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