Yoshi-Nori Nakamura

Relationship among collagen amount, distribution and architecture in the M. longissimus thoracis and M. pectoralis profundus from pigs.

The relative distribution of types I and III collagens and collagen fibre architecture in the perimysium and endomysium were compared to the longissimus thoracis (LT) and pectoralis profundus (PP) muscles in pigs. The LT muscle was composed of type I myofibres 16.8%, IIA 12.9% and IIB 70.2%, and the PP muscle was 25.4, 23.1 and 51.5%, respectively. The total collagen amount differed significantly between the LT (2.66 mg/g) and PP (4.13 mg/g) muscle (P<0.001). On image analysis of the immunohistochemical preparations for types I and III collagens, the percentage area of the perimysium to the total collagen area showed significant differences between the muscles, where perimysial type I collagen occupied 25.4% of the total area in the LT muscle and 45.7% in the PP and perimysial type III 37.6 and 54.5%, respectively (P<0.001). In scanning electron microscopic photographs of the macerated preparation, very thick collagen layers composed of several fibre bands were observed in the perimysia of the PP muscle and appeared differently from the thinner perimysia with a few bands in the LT. Similar architecture of endomysial collagen fibres were observed around every myofibre type in the PP muscle and also in the LT. The fine surface cover of reticular collagen fibres around an adipocyte was shown as a global cast. These results suggested that the total collagen amount of the PP muscle was related mainly to the well developed perimysia composed of several collagen bands, indicating tougher meat compared with the LT muscle.

Developmental states of the collagen content, distribution and architecture in the pectoralis, iliotibialis lateralis and puboischiofemoralis muscles of male Red Cornish x New Hampshire and normal broilers.

1. Developmental states of the collagen content, distribution and architecture in the pectoralis (PT), iliotibialis lateralis (ITL) and puboischiofemoralis (PIF) muscles of male Red Cornish × New Hampshire (RN, 80 d, body weight 2·9 kg) and normal (3·1 kg) broilers were evaluated. 2. In PT muscle the total amount of collagen was significantly greater in RN broilers (3·33 mg/g) than in normal ones (1·71 mg/g). This higher collagen content in RN broilers was based mainly on the closer mesh sizes of endomysial honeycomb. The collagen structures in the perimysia also differed between broiler types, when more collagen fibres were observed in RN broilers. 3. ITL muscle contained total collagen of 4·10 to 5·00 mg/g. Types I and III collagens were distributed on the perimysia at higher percentages in RN broilers (31·6%, 37·2%) than normal (15·6%, 30·8%), respectively. The thick bands of tough collagen fibres characteristic of ITL muscle perimysium in cockerels had not yet developed in these broilers. 4. Total collagen was 4·63 to 6·29 mg/g in PIF material with fascia. In PIF muscle the perimysial collagen fibres had not yet attained their full growth but consisted of densely packed fibrils. PIF muscle was characterised by the earlier maturing collagen structure. 5. These results show that a perimysial collagen structure in broilers is still in an undeveloped state. It is supposed that tenderness of broiler meat is attributed mainly to characteristics of the collagen distribution, in which the majority of types I and III collagens is distributed on the closer mesh of endomysial honeycomb.

Growth changes of the collagen content and architecture in the pectoralis and iliotibialis lateralis muscles of cockerels

1. Growth changes of the collagen content and architecture in the pectoralis (PT) and iliotibialis lateralis (ITL) muscles were examined using cockerels from 1 to 14 weeks of age. 2. Total collagen content in PT muscle showed little change, but in ITL muscle reached a maximum at 5 weeks and thereafter decreased slightly until 14 weeks. The collagen content was markedly larger in ITL muscle after 5 weeks. Pyridinoline content of collagen increased abruptly from 5 to 14 weeks in both muscles, but no difference between muscle types was detected. 3. The cell size of the endomysial honeycombs increased with the development of myofibres, and the mesh size of the perimysium around the honeycombs enlarged. 4. In both muscles endomysia were an incomplete network of collagen fibrils with many foramina at one week, became a very thin membrane of felt-like fabric in 2 to 5 weeks and thereafter increased in thickness until 11 to 14 weeks. 5. Perimysial width around the secondary fasciculus differed between the muscle types after 5 weeks. In the wider perimysium of ITL muscle, the collagen fibres increased in number and size to make a stack of collagen bands around the fasciculus. In the narrower perimysium of PT muscle, a few platelets of collagen fibres also developed. 6. The perimysial collagen fibre at 1 to 2 weeks had a smooth surface and appeared to be composed of fine collagen fibrils. The fibre at 11 to 14 weeks showed a rugged surface and was composed of coarser collagen bundles that combined with each other into a net-like configuration with very slim meshes. 7. Our results showed that the collagenous components of chicken intramuscular connective tissue changed markedly during the early period of muscle growth in distribution, architecture and quality but with little difference in quantity.

Comparison of collagen fibre architecture between slow-twitch cranial and fast-twitch caudal parts of broiler M. latissimus dorsi

1. Collagen fibre architectures of perimysium and endomysium in the slow-twitch cranial and fast-twitch caudal parts of broiler M. latissimus dorsi were compared. 2. Type I and III collagens were distributed in both perimysium and endomysium as indicated by their positive immunohistochemical reactions to polyclonal antibodies. 3. Cells invested by endomysium with no myofibres were larger in the cranial part because of the presence of larger slow-twitch myofibres. The honeycomb structure of endomysium was divided into several parts by thick perimysium. 4. The thick perimysial collagen fibres with parallel fibrils, which were interconnected by the loose reticular fibrils and thin fibres, were more numerous and thicker in the cranial part than the caudal. 5. Thick endomysial sidewall of cells in the cranial part was composed of a rougher reticulum of slightly thicker collagen fibrils compared with the thin sidewall in the caudal part. 6. These results indicated that both perimysial constitutions of collagen fibres and endomysial collagen fibrils had attained much larger growth in the slow-twitch cranial part than the fast-twitch caudal in broiler latissimus dorsi muscle.

Histological contribution of collagen architecture to beef toughness.

The relationship between shear-force value and collagen architecture of connective tissue of the longissimus thoracis (LT) muscle of Japanese Black (n = 10) and Brown (Kumamoto) (n = 5) steers (body weight: 688.4 +/- 8.6 kg as average and standard error) was investigated. There were negative correlations between the shear-force value and lipid content (n = 15, R(2)= 0.3709, P < 0.01) and protein content and lipid content (n = 15, R(2)= 0.6748, P < 0.01). Shear-force value and collagen content (n = 15, R(2)= 0.4344, P < 0.01) were positively correlated. In scanning electron microscopic photographs of the macerated preparation, the perimysium of the high-lipid LT muscle was broken down compared with the low-lipid LT muscle. The endomysium in all LT muscle fibers showed similar architecture. The fine surface cover of reticular collagen fibers around an adipocyte was observed in the high-lipid LT muscle perimysium. These results suggested that the shear-force value of the LT muscle was related to change in collagen architecture and of the perimysium in particular.

Effects of feeding level of milk replacer on body growth, plasma metabolite and insulin concentrations, and visceral organ growth of suckling calves

The objective was to evaluate effects of feeding level of milk replacer on body growth, plasma metabolite and insulin concentrations, and allometric growth of visceral organs in suckling calves. Holstein bull calves (n = 8; 3-4 days of age) were fed either a low amount (average 0.63 kgDM/day, LM) or high amount (average 1.15 kgDM/day, HM) of high protein milk replacer until they were slaughtered at 6 weeks of age. Body weight (BW) at 4, 5, and 6 weeks of age, feed intake, average daily gain, and feed efficiency were higher in the HM than LM calves. The HM group had higher plasma glucose at 3 and 4 weeks of age and insulin levels after the age of 4 weeks compared with LM calves whereas no effect was detected on plasma nonesterified fatty acid or urea nitrogen concentrations. The HM calves had greater empty body weight (EBW), viscera-free BW and most of the organs dissected than LM calves. Relative weights (% of EBW) of liver, spleen, kidneys, and internal fat were higher, whereas head and large intestine was lower in HM than LM calves. The results suggest that increased milk feeding levels would accelerate the growth of the body and specific organs.

Fatty acid profiles and adipogenic gene expression of various fat depots in Japanese Black and Holstein steers

Objective of the study was to assess the breed effect on fatty acid (FA) composition of different adipose tissues and on mRNA expression of genes involved in adipogenesis and fat metabolism. Japanese Black (JB) and Holstein (HS) steers were kept under equivalent conditions with high energy intake resulting in large differences in intramuscular fat (IMF) accumulation in longissimus muscle (LM). The relative FA composition of muscle, intermuscular fat, visceral fat, and perirenal fat was comparable between JB and HS steers. Circulating fatty acids were also similar in both breeds. Most relevant breed effects were identified in IMF, underlining the uniqueness of this adipose tissue site. JB steers had more monounsaturated FA and less saturated FA. Perilipin 1 and adipose differentiation-related protein (ADFP) mRNA levels were higher in IMF of JB. The results suggest advanced maturity of IMF cells in JB and altered local conditions in muscle influencing IMF accumulation and composition.

Dietary CLA and DHA modify skin properties in mice

This study investigated the influence of PUFA on the properties of mouse skin. Mice (3 wk old) were given free access to oils high in linoleic acid, CLA, or DHA for 4 wk. At the end of the experiment, their skins were compared by both biochemical and histological methods. No significant differences in lipid and collagen contents were detected among treatments, although the FA composition in the skin was altered depending upon the FA composition of the supplemented oils. Electron microscopy revealed that the subcutaneous tissue layers in the CLA and DHA groups were significantly thinner than that in the high linoleic acid group, whereas no differences in the thickness of dermis layers were observed among the three groups. These results suggest that skin properties in mice are readily modified by dietary FA sources within 4 wk of dietary oil supplementation.

Modification of skin composition by conjugated linoleic acid alone or with combination of other fatty acids in mice.

The effects of conjugated linoleic acid (CLA), gamma-linolenic acid (GLA), linoleic acid (LA), and their combinations, on skin composition in mice were investigated. Mice (8 weeks old) were orally administered with either LA, GLA, CLA, LA + GLA, LA + CLA, or CLA + GLA for 4 weeks. Then, the skin was analysed for triacylglycerol content, fatty acid composition and collagen content. Additionally, thicknesses of the dermis layer and subcutaneous tissue layer, and the size and number of adipocytes were measured histologically. The skin fatty acid composition was modified depending upon the fatty acid composition of supplemented oils. In each oil-alone group, skin triacylglycerol content was the highest in LA, followed by GLA and CLA treatments. Combinations with CLA had a similar triacylglycerol content compared with the CLA-alone group. No significant changes in collagen content were observed among any treatments. The effects on subcutaneous thickness were similar to the results obtained in the triacylglycerol contents, where groups supplemented with CLA alone or other fatty acids had significantly thinner subcutaneous tissue compared with the LA-alone group. However, no significant difference was detected in the thickness of the dermis layers. The number of adipocytes was highest in the LA + GLA group and tended to be reduced by CLA with or without the other fatty acids. These results suggest that CLA alone or in combination with other fatty acids strongly modifies skin composition in mice.

Changes in Plasma Composition of Japanese Black Steers During Grazing and Fattening Periods

Abstract Nakamura, Y.-N., Orito, H., Tsuneishi, E., Hirano, K., Kato, N., Shoji, A., Kamiya, M. and Nakanishi, Y. 2008. Changes in plasma composition of Japanese black steers during grazing and fattening periods. J. Appl. Anim. Res., 34: 157–161. The plasma compositions of five Japanese black steers during about 23 months of grazing and fattening period of about 6 months were investigated. Plasma A/G, LDH, Glu, tCho and Ins concentrations increased (P<0.05), whereas TG, UNandNEFA concentrations decreased (P<0.05) during the fattening period. Plasma Na concentration increased (P<0.05) during the fattening period. Plasma Bβ-carotene and tocopherol concentrations decreased (P<0.05) during the fattening period. Changes in plasma chemical composition during grazing and fattening were related to the chemical composition of the feed consumed and lack of exercise during housing.