Fundamental studies on the meat production of the domestic fowl : V. Comparison of postnatal growth of individual muscle and its sexual differences

Male and female chicks of Rhode Island Red with normal growth were used for this study. Twenty-four individual muscles were weighed on the chicks\u27 right. Postnatal growth of individual muscles were compared with each other, and its sexual differences were studied. The results were as follows: 1. In I-period (0-2 weeks old), individual muscles of the forelimbs\u27 part, for example, M. pectoralis superficialis, M. pectoralis profundus and M. triceps brachii, grew and developed very rapidly, but M. biceps femoris and M. semimembranosus intermediately, and the other muscles more slowly than those muscles in both sexes. 2. In II-period (2-22 weeks old), individual muscles of the hind legs\u27 part, for example, M. peroneus longus, M. semimembranosus, M. biceps femoris and M. triceps surae, grew and developed a little more rapidly than the other in the male. And M. peroneus longus, M. biceps femoris, M. semimembranosus and M. pectoralis profundus, etc., grew and developed a little more rapidly than the other in the female. 3. In III-period (22-26 weeks old), individual muscles of the hind legs\u27 part, for example, M. peroneus longus, M. biceps femoris, M. semimembranosus and M. semitendinosus and so on, grew and developed very rapidly in the male. But in the female, all the individual muscles did not grow and develop, or did only a little. 4. In IV-period (after 26 weeks old), individual muscle weights of the 32 weeks old were little heavier than those of the 26 weeks old in the male. 5. From these results mentioned above, individual muscles were divided into six groups as follows: The first A-group (M. pectoralis profundus, M. coracobrachialis externus and M. teres major et infraspinatus): These muscles grew and developed very rapidly during I-period, and rapidly during II- and III-period also. But the rate of growth of these muscles during II- and IIIperiod was similar to that of the third C-group in the male, because these did not show any sexual characteristics of the male. The first B-group (M. pectoralis superficialis, M. latissimus dorsi, M. deltoideus, M. triceps brachii, M. biceps brechii and M. extensor carpi radialis brevis): These muscles grew and developed very rapidly during I-period like the first A-group. But during II- and III-period these grew and developed more slowly than the first A-group. The rate of growth and development of these during II- and III-period was worst of all groups in the male, because these did not show any sexual characteristics of the male. The second group (M. biceps femoris and M. semimembranosus): These muscles grew and developed intermediately during I-period, and very rapidly during II- and III-period. Particularly in the male these made remarkable progress during II- and III-period. The third A-group (M. semitendinosus, M. quadriceps femoris, M. gracilis, M. triceps surae and M. peroneus longus): These muscles grew and developed more slowly during I-period, but very rapidly during II- and III-period. Particularly in the male these made remarkable progress during II- and III-period like the second group. The third B-group (M. gluteus medius, M. gluteus superficialis, M. tensor fasciae latae and M. tibialis cranialis): These muscles grew and developed more slowly during I-period. The rate of growth of these during II- and III-period was similar to that of the first B-group in the female. But in the male, these grew and developed intermediately during II- and III-period, for the rate of growth of these was better than the first A-group, or worse than the second group and the third A-group. The third C-group (M. semispinalis cervicis, M. longus colli, M. sartorius and Mm. adductores): These muscles grew and developed more slowly through all the experimental period. But in the male, the rate of growth of these during II- and III-period was alike the first A-group owing to the sexual characteristics of these muscles.RIR種雌雄鶏を用いて,鶏体の右側において計24個の個々の筋肉重量を計測した.そして,個々の筋肉の成長を比較し,また,その雌雄間の相違についても検討を行なつた.その結果は次の通りであつた. 1. I期では,浅胸筋,深胸筋,上腕三頭筋等の前肢部に入る個々の筋肉で成長が極めて著しかつた.大腿二頭筋と半膜様筋は中間的な成長の速さを示し,その他の後肢部と頸部の筋肉はもつとも成長が劣つた. 2. II期では,雄は長腓骨筋,半膜様筋,大腿二頭筋,下腿三頭筋等の後肢部に入る個々の筋肉で成長がやや勝り,雌では長腓骨筋,半膜様筋,大腿二頭筋,深胸筋等で成長がやや勝つた. 3. III期は性成熟完成期と一致し,雄では後肢部に入る個々の筋肉で他の部位の筋肉より判然と成長が勝り,その主なものは長腓骨筋,大腿二頭筋,半膜様筋,半腱様筋等であつた.一方,雌ではII期とほぼ変らず,ほとんど成長を示さなかつた. 4. IV期では,雄の32週齢における個々の筋肉重量は26週齢のそれとほとんど変らなかつた. 5. 以上のような各期を通じての成長経過から,個々の筋肉を次のような6つのグループに分けた.第1グループ,A(深胸筋,外鳥口腕筋ならびに大円および棘下筋);I期における成長が極めて著しく,その後の成長も著しかつたもの.しかし,雄においては,性的特異性を全く受けなかつたので,II,III期における成長は第3グループ,Cの成長とほとんど変らなかつた.第2グループ,B(浅胸筋,広背筋,三角筋,上腕三頭筋,上腕二頭筋ならびに短嶢側手根伸筋);I期における成長が極めて著しく,II期以後の成長が第1グループ,Aより劣つたもの.さらに雄においては性的特異性を全く受けずII,III期における成長はもつとも劣つた.第2グループ(大腿二頭筋ならびに半膜様筋);I期においてこれらは中間的な成長の速さを示し,II,III期には極めて良く成長したもの.特に雄においてII,III期の成長が著しかつた.第3グループ,A(半腱様筋,大腿四頭筋,薄筋,下腿三頭筋ならびに長腓骨筋);I期における成長はもつとも劣つたが,II,III期の成長は第2グループとともに極めて著しかつたもの.特に雄でこの傾向が強かつた.第3グループ,B(中殿筋,浅殿筋,大腿筋膜張筋ならびに前頸骨筋);I期における成長はもつとも劣つたが,II,III期の成長は雌では第1グループ,Bとほとんど等しく,雄では第1グループ,Aより勝つたが,第2グループと第3グループ,Aより劣り,中間的な速さであつた.第3グループ,C(頸半練筋,頸長筋}縫工筋ならびに内転筋はI期でもその後も,もつとも成長が劣つたグループ.しかし,雄においては性的特異性により,II,III期の成長は第1グループ,Aとほとんど変らなかつた