Hitoshi Takahara

Different growth rates of male chicken skeletal muscles related to their histochemical properties

1. Early, M. pubo-ischio-femoralis pars medialis (PIF muscle) and late, M. iliotibialis lateralis pars postacetabularis (ITL muscle), maturing muscles were studied. These two muscles contained different populations of histochemical fibre types. 2. The profile measurements of the muscles showed diphasic allometric growth relative to the weights. In the early stage of growth (up to 15 weeks after hatching), the muscle length, width and depth all increased, while in the later stage (from 15 to 35 weeks) muscle growth resulted mainly from the marked increase in the depth and to a lesser degree, from an increase in the width. 3. Type I fibres, observed predominantly in PIF muscle matured earlier than the Type II fibres of ITL muscle. 4. From these results, the detailed process of skeletal muscle growth in the chicken was discussed.

Breed differences in the histochemical properties of the M. Iliotibialis lateralis myofibre of domestic cocks

1. Reduced nicotinamide adenine dinucleotide dehydrogenase (NADH-DH) activity in the M. iliotibialis lateralis was compared histochemically among 7 breeds of cocks. This muscle was composed only of Type-IIA and -IIB fibres. 2. Apparent breed differences were observed in muscle development, the NADH-DH activity in every fibre type, fibre type distribution and fibre diameters. 3. From the results of this study, it was concluded that the muscle characteristics of various breeds were based not only on the fibre type composition, but also the different activities of oxidative enzyme in every type.

Breed differences in the histochemical properties of the M. pubo‐ischi‐ofemoralis pars medialis myofibre of domestic cocks

1. Histochemical properties of M. pubo-ischio-femoralis pars medialis (PIF muscle) were compared in 7 breeds of cocks. This muscle was largely composed of Type I fibres and their transitional form (Type I tr). Type IIA fibres were observed in the cranial part. 2. The weight and cross-sectional area of the PIF muscle increased with increasing body weight. However, the relative muscle development to body weight differed among the 7 breeds. 3. A quarter of Type I fibres were of the transitional variety in bantam fowls. Conversely, few, if any, Type I tr fibres were observed in the large breeds where the muscle was poorly developed. 4. As the histochemical properties of Type I fibres made an effective response to the different body weights and the relative PIF muscle development among breeds, it was concluded that PIF muscle performed an important function in supporting the body weight and maintaining posture.

Comparative studies on the histochemical properties of M. iliotibialis lateralis from Kumamoto Cochin crossbred roaster and broiler chickens

1. Histochemical properties of M. iliotibialis lateralis were compared between Kumamoto Cochin (a Japanese native breed) crossbred roasters (KC roasters, 112 d of age) and normal broilers (56 d of age). 2. Myofibres were divided into Types II-R, II-I and II-W showing high, moderate and low reduced nicotinamide adenine dinucleotide dehydrogenase (NADH-DH) activities, respectively. 3. Subsarcolemmal formazan granules indicating very strong NADH-DH activity in Type II-R fibres were observed only in KC roasters. In both sexes the percentage of Type II-R fibres present was greater in KC roasters than in broilers. 4. These results indicated marked differences in histochemical properties and meat quality between KC roasters and broilers.

Interrelationships between the Histological Properties of Biopsy Muscle Materials and Beef Marbling Score in the Japanese Black Steers

Fifteen Japanese Black steers engaged in progeny test of two sires were used in this study. Histological properties of biopsy materials taken from longissimus lumborum and biceps femoris muscles were observed at 9-10 months old. Intramuscular fatty tissue, perimysium deposits, was detected already at this age with individual difference in its development. In the longissimus, the histological volume score of the fatty tissue was related significantly to beef marbling score (BMS) of the carcass at 21-22 months old (p<0.05). Correlation coefficient between percentage of Type αW fibers and BMS was also significant (p<0.05). In the biceps, these coefficients were not significant. These results indicated that BMS could be estimated from the early observation of the perimysium deposits in the longissimus muscle.

The Effect of Denervation on the Degenerative Process of Type I Fibers in the Biceps Brachii Muscle of the Chick

An intact, healthy and active nerve supply is required for normal muscle growth and function. Denervation is a general procedure to assess correlations between motor nerves and muscle growth. It is well known that denervation leads to a number of functional changes, including fiber atrophy5,20 ). The influence of denervation of muscle, however, is also different in the developmental stage of animals17). In a previous study12), we reported that type I fibers of the intact brachial muscles (biceps brachii, scapulotriceps and humerotriceps mucles) showed a degenerative process in early posthatching development. However, it is not known if the degeneration of type I fibers is under the control of the motor nerve. In response to the previous results12), this study was designed to examine what kind of role the motor nerve plays in the degenerative process of type I fibers or in the developmental process of the biceps brachii muscle, by cutting the motor nerve supply to muscles in a chick. Materials and Methods

Effects of zinc on intact and castrated cockerels

1. Fourteen-week-old intact and castrated cockerels (White Leghorn) were injected intramuscularly with zinc (100 micrograms/kg body weight) as zinc ammonium sulphate solution once daily for 4 weeks and the effects on testes, pituitary and adrenal glands investigated histologically. 2. In intact cocks zinc decreased testes weight significantly, inhibited spermatogenesis and disturbed testicular hormone production. There was an increase in pituitary gonadotrophic cell activity, perhaps an indication of feed-back response to low concentration of testicular hormone. Cortical and medullary cells of the adrenal glands showed signs of activation. 3. No discernible effects of zinc injection on pituitary and adrenal cells of castrates were observed. This may reflect a decrease in pituitary and adrenal responsiveness to repeated stimulation with zinc. 4. The results indicate that the effectiveness of a given dose of zinc was dependent on the physiological condition of the cockerels and the effective site of zinc action was centred in the testes.