Growth equations for skeletal muscle derived from the cytonuclear ratio and growth constraining supplementary functions

Roux, C. Z.

doi:10.1017/s1357729800050153

Cited by 5 publications

(3 citation statements)

References 30 publications

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“…In the description of protein growth, the ensuing theory is comparable to an approach derived from growth postulates of Baldwin & Black (1979). This can be demonstrated by the transformation of PS rate as a DNA power relationship to a protein content power relationship by substituting DNA / (P/a) 2/3 (Roux, 1999). For the wholebody situation, it follows that the relationships of Oltjen et al (1985) provide an estimate of PR efficiency on rats from weaning onwards identical to the present one derived from equations 9 and 22, with Q ¼ 1 and Y ¼ 1/2 (Roux, 2005a).…”

Section: Comparison With An Alternative Approachmentioning

confidence: 74%

“…The number of multinucleate skeletal muscle cells does not increase after birth (Swatland, 1984) so that Y ¼ 1 for skeletal muscle. Generally, the total amount of DNA, and hence nn, in the whole body of rats follows the relationship (nn) / (P/a) 2/3 (Roux, 1999). Moss (1968) reports that this is also true for skeletal muscle as long as fibre length continues to increase.…”

Section: Values Of Y and Jmentioning

confidence: 97%

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Incorporating turnover in estimates of protein retention efficiency for different body tissues

Roux

2006

Br J Nutr

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Formulated in terms of protein synthesis (PS) and protein retention (PR), a definition of turnover-related protein retention efficiency (k P ) allows the expression k P ¼ ½1 þ ðPS=PRÞ=6 21 , 6 representing the ratio of the energy equivalent of protein to the cost of synthesis. By combining plausible hormonal and cellular control mechanisms of protein (P) growth, it is possible to derive ðPS=PRÞ ¼ ½Q{ðP=aÞ 2ð4=9ÞY 2 1} 21 þ 1, allowing the calculation of k P by substitution. The symbol a represents the limit value of protein growth, while the term 4/9 derives from the power in the relationship between the concentration of growth factor-related activator in the nucleus and cell volume (cv). Y is the power in the relationship between cv and total tissue protein, and Q represents the proportion of growth factor-activated nuclei in a tissue. The proportion Q can be estimated from simple functions of intake rates or blood growth factor concentrations. Estimates of Y are derived from histological considerations or calculated from experimental observations; Y ¼ 1 for multinucleated skeletal muscle fibres and Y ¼ 1/3, 1/2, 1/6 on average for mononucleated cell tissues, skin or bone and viscera, respectively. To apply k P to the whole body, an average value of Y ¼ 1/2 can be taken. Experimental observations on tissue protein synthesis and breakdown rates yield direct estimates of k P in satisfactory agreement with comparable theoretical predictions. Protein turnover: Protein retention efficiency: Body tissuesBergen and Merkel (1991) suggested that the discrepancy between regression estimates of protein retention (PR) efficiency and theoretical estimates of synthesis efficiency indicated a major contribution ascribable to protein turnover in the generally accepted estimates. Quantification by Roux (2005a,b) has shown that this is indeed the situation for whole-body PR efficiency in pigs, cattle and sheep.Theoretical values for the parameters in Roux (2005a) were derived using the assumption that heart values are representative of average values for the whole body. It was shown that the difference between protein synthesis and breakdown related to body protein according to the relationship between nuclear and tissue sizes during growth. It follows that ideas used in whole-body and heart scaling by Roux (2005a) can be extended to accommodate different aggregates of body tissues. In addition, two improved derivations are given in this paper. First, previously neglected ribosomal scaling (Roux, 2005a) is accommodated. Second, an exact estimate of k P is derived and compared with the previous approximation (Roux, 2005a), necessary for application in conjunction with established equations for growth description in the literature.From a nutritional standpoint, differences in PR efficiency between tissues are important in two ways. The first is for predicting nutrient requirements for growth in different tissues from turnover-related efficiencies; the second is for estimating the contributions to maintenance from protein turnov...

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Section: Comparison With An Alternative Approachmentioning

confidence: 74%

Section: Values Of Y and Jmentioning

confidence: 97%

Incorporating turnover in estimates of protein retention efficiency for different body tissues

Roux

2006

Br J Nutr

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“…Because body mass increases are mostly dominated by muscle mass increases and because the former is sigmoidal in form from conception to maturity (see also Chapter 10), it follows that increases in total muscle will be likely to approximate to the sigmoidal form. Roux (1999) proposes that the sigmoidal shape of the muscle mass growth curve can be explained by the lack of constancy in the cytonuclear ratio, the hypothesis being that the speed of growth of nucleus numbers depends primarily on this ratio and is descriptive of the hypertrophic phase of growth which dominates most of the postnatal period.…”

Section: Normalmentioning

confidence: 99%

Growth of farm animals

2012

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Index x Contents Preface to First EditionAn understanding of the processes which change the size, shape and composition of farm animals is fundamental to all aspects of production which seeks to meet the dietary and other needs of human populations. This book attempts, within the limits of a basic undergraduate text, to give a comprehensive picture of how animals grow, change in shape and in composition, and to describe those factors which affect growth processes and which dictate the extent and direction of changes within the animal.The overall scene we have attempted to present is a progression from cell to tissue to entire animal, as well as a description of those factors within the animal, particularly hormones, genes and gender, which fashion this progression. In addition, an attempt has been made to give perspective to the manner in which such a complexity of changes affects the approach to, and understanding of, concepts of efficiency. However, it was felt that the framework would not be complete without first setting the scene in the context of some of the principles which govern size and shape in all animals and, second, describing the methods which may be used to measure the overall results of the processes which have been described. Deliberately, the effect on growth which exogenous factors such as hormonal implants, antibiotics and other intestinal tract manipulators may have has not been considered. Although the use of such manipulators may be transitory and dependent on political and other pressures, basically they were not considered to be appropriate to the general thesis. Whilst it is acknowledged that poultry are farm animals of great importance in producing food for the human, largely through a dearth of appropriate detailed information and because of the approaches to production which are used in practice, this book concentrates on cattle, sheep and pigs.In our student days we were endlessly fascinated by the seminal studies of D'Arcy Thompson, by the profound work of Brody at Missouri and by the inspired and inspiring work and writing of Hammond and his associates at Cambridge. To no less an extent we found the sheer variety of animal cells and the immensely complex tissues that they form, and which give ultimately the overall growth responses, both amazing and mind gripping. These fascinations have remained with us ever since and in our working lives we have been fortunate to have had the chance to make some contributions to some of those areas which have so consistently intrigued us and occupied our thoughts. As students the writings of those great men above were those to which we turned. Today much of their basic thinking still holds good and leads the enquiring mind in the right direction when considering the problems of how best farm animals may be grown to yield products for the human. However, there is no book which as a complete entity has updated their basic thinking and which takes the reader from cell to complete animal based on original classical anatomical studies and the quantit...

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Indices of cellular development in muscles of lambs are influenced by sire estimated breeding values and pastoral nutritional system

Greenwood

Gardner

Hegarty

2006

Aust. J. Agric. Res.

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This study examined influences of sire (n = 9) estimated breeding values (EBVs), sire-group (Muscle, Growth, and Control), and nutrition (low and high quality and availability pasture) from birth to slaughter at ~8 months of age on indices of muscle cellularity and transcriptional and translational capacity in 56 castrate lambs. Effects of nutritional systems to 8 months of age were greater, overall, than those due to EBVs or sire-group. Amount of DNA increased with increasing EBV for post-weaning eye muscle depth (PEMD or Muscle EBV) in longissimus but not in semimembranosus and semitendinosus muscles, while Muscle EBV also had an inverse association with concentration of DNA. Protein to DNA and RNA to DNA were related positively to Muscle EBV, the associations being strongest for the semitendinosus muscle. Post-weaning weight (PWWT or Growth) EBV correlated positively with the RNA to DNA ratio and, among high but not low nutrition lambs, was inversely related to concentration of muscle DNA, whereas post-weaning fat depth (PFAT or Fat) EBV was correlated positively with RNA concentration. Overall, the magnitude of effects of sire-group was less than for sire EBVs, presumably due to differing selection pressures for muscling, fatness, and growth. High nutrition lambs had more protein to DNA than low nutrition lambs in the longissimus and semitendinosus muscles, but not in the semimembranosus muscle. In low compared with high nutrition lambs, concentration of DNA was greater in the longissimus and semitendinosus muscles. Total amount of DNA was reduced by more in low compared with high nutrition in the longissimus and semimembranosus than in the semitendinosus, and amount of protein was reduced by more in low compared with high nutrition in the longissimus than in the other two muscles. We conclude that genetic selection for eye muscle depth in sheep has differing effects on cellular characteristics of the longissimus, semimembranosus, and semitendinosus muscles, and has greater effects on muscle cellular characteristics than genetic selection for post-weaning weight or fat depth.

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Growth equations for skeletal muscle derived from the cytonuclear ratio and growth constraining supplementary functions

Cited by 5 publications

References 30 publications

Incorporating turnover in estimates of protein retention efficiency for different body tissues

Incorporating turnover in estimates of protein retention efficiency for different body tissues

Growth of farm animals

Indices of cellular development in muscles of lambs are influenced by sire estimated breeding values and pastoral nutritional system

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