A family of protein growth curves with extension to other chemical body components together with application to animal nutrition and improvement

Roux, C. Z.

doi:10.1017/s1751731110001874

Cited by 3 publications

(10 citation statements)

References 25 publications

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“…Roux (2005b) gave estimates of (P/α) = 0.741 and 103.8 kg for the steers and (P/α) = 0.355 and α = 11.81 kg for the wethers. Roux (2011) provided evidence that the constant c in equation (12) should vary with α 3/4 across different animal types. As the power 8/9 in equation (12) is applicable to protein breakdown, the protein breakdown rates of Lobley et al (1987) for cattle can be transformed to:…”

Section: Augmentation Of Maintenance For Body Protein Resynthesismentioning

confidence: 99%

“…with PR(max) designating the maximum protein retention for an animal at a given degree of protein maturity, P/ (Roux, 2011). Other possible estimators of Q are discussed in Roux (2011), together with the circumstances under which they may be applicable.…”

Section: Theoretical Efficiencies Of Protein Retention and Synthesismentioning

confidence: 99%

“…Other possible estimators of Q are discussed in Roux (2011), together with the circumstances under which they may be applicable. However, intake prediction problems associated of Q can be avoided by use of equation (6.4) below, together with equations (14.1) to (15.3).…”

Section: Theoretical Efficiencies Of Protein Retention and Synthesismentioning

confidence: 99%

“…From a study of mammalian protein growth curves based on PR as the difference between PS and PB, Roux (2011) provided evidence that the whole body median relationship across species is probably:…”

Section: Augmentation Of Maintenance For Body Protein Resynthesismentioning

confidence: 99%

“…From Roux (2011) it can be derived that the points of inflection of the protein curves of IGM and DGM are far apart, respectively, 0.37 and 0.19 of mature protein mass. The observed growth curves reported in Garcia et al (2008) started at about 0.3 of mature body mass, too late for differences between IGM and DGM owing to inflection points to be detected in the protein growth predictions.…”

Section: Extension To Dynamic Systemsmentioning

confidence: 99%

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Use of theoretical efficiencies of protein and fat synthesis to calculate energy requirements for growth in ruminants

Roux¹

2014

SA J. An. Sci.

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The main objection against conventional net energy systems is that owing to variation in gain composition and the different energy contents of protein and fat, the efficiency of energy gain cannot be regarded as a growth constant. The present approach shows that the separate accommodation of protein and fat in predicting ruminant nutritional requirements can easily be achieved, since growth energy retention efficiency can be replaced by protein and fat synthesis efficiencies, together with an augmentation of maintenance with the cost of protein turnover. The synthesis efficiency of protein (k PS ) is taken to be k PS = (q L /q M )(6/7), with 6/7 the synthesis efficiency of protein, q L the metabolizability of the diet at an arbitrary level (L) of intake and q M the metabolizability of the diet at maintenance. The correction (q L /q M ) allows for the usual evaluation of ruminant diets at the maintenance level of intake. The synthesis efficiency of fat from fermentation of digestible fibre is k FF = 1.018q M or k FF = 1.287k g , without the necessity of adjustment by q L /q M , since evaluation of metabolizability at maintenance is incorporated in the relationship between k FF and q M and where k g denotes growth energy efficiency. Maintenance estimated from fasting heat production or intake at zero energy retention should be augmented by the cost of protein turnover from (PB/6) ÷ (q L /q M ), with PB/6 = 102.7 kJ/kg (FW) 0.75 per day for cattle and PB/6 = 78.1 kJ/kg (FW) 0.75 per day for sheep, where PB denotes protein breakdown and FW fasted body mass. Alternatively, with knowledge of the degree of protein maturity, body protein turnover can be incorporated in a theoretically derived estimate of protein retention efficiency. The effective energy system can also be improved by employing theoretical protein retention and fat synthesis efficiencies or by equivalently replacing protein retention efficiency by protein synthesis efficiency in conjunction with the augmentation of maintenance heat production by the cost of protein turnover. A comparison between average growth energy efficiencies shows excellent agreement between estimates of the present theory and those of the UK Agricultural Research Council (ARC) and the US California Net Energy System (CNES), with degrees of maturity together with protein and fat gain ratios that seem typical of original experimental conditions. This implies that the present approach should do at least as well as the ARC or CNES, but can be expected to do better with reasonable accuracy in estimating the degree of protein maturity or maintenance augmentation and the composition of energy gain. The relationship between conventional growth energy efficiency and the synthesis efficiency of fat from digestible fibre allows the accumulated information of net energy systems to be transferable to the new methodology.________________________________________________________________________________

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Section: Augmentation Of Maintenance For Body Protein Resynthesismentioning

confidence: 99%

Section: Theoretical Efficiencies Of Protein Retention and Synthesismentioning

confidence: 99%

Section: Theoretical Efficiencies Of Protein Retention and Synthesismentioning

confidence: 99%

Section: Augmentation Of Maintenance For Body Protein Resynthesismentioning

confidence: 99%

Section: Extension To Dynamic Systemsmentioning

confidence: 99%

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Use of theoretical efficiencies of protein and fat synthesis to calculate energy requirements for growth in ruminants

Roux¹

2014

SA J. An. Sci.

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A family of protein growth curves with extension to other chemical body components together with application to animal nutrition and improvement

Roux

2011

Animal

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Theory that successfully explains the magnitude and range of estimates of protein retention (PR) efficiency from the cost of turnover of existing protein indicates that conventional curves for growth description are inappropriate for protein growth. A solution to this problem is found in the consideration that the rate-limiting steps for protein synthesis (PS) and breakdown are likely to be associated with the diffusion of metabolites in and between cells. The algebraic scaling of nuclear and cellular diffusion capacity with tissue or total body protein leads to a parameterization of the primal differential equation for PR (kg/day) based on two terms representing PS and breakdown, viz.where c is an arbitrary constant, Q is the proportion of nuclei active in cell growth or division in a tissue or the whole body, a is the limit mass for protein (P, kg) in a tissue or the whole body, the power X 1 Z represents the rate-limiting steps in protein breakdown and Y is the power of the relationship between cell volume and the amount of tissue protein. For the whole body, the contribution of the different tissues should be weighted in proportion to their PS rates with, on average, Y 5 1/2. The constant 4/9 arises from the scaling of the specific diffusion rate of DNA activator precursors from nuclear dimensions and from the relationship between nuclear and cell volume. Experimental evidence on protein breakdown rate as well as protein and body mass points of inflection indicates that the range of theoretically possible numerical values of the rate-limiting powers X 1 Z 5 ( i 1 3)/9 for i 5 1, 2, y ,12 seems adequate for the description of the range of observed whole body protein and body mass growth patterns for mammals. Q 5 1 represents maximal protein retention, and for 0 , Q , 1, experimental evidence exists in support of a theoretical relationship between Q and food ingestion. The conclusion follows that some knowledge of the protein limit mass (a) and of the point of inflection (related to X 1 Z) is the main requirement for the application of the theory for description and prediction in animal nutrition and breeding.

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Use of theoretical efficiencies of protein and fat synthesis to calculate energy requirements for growth in ruminants

Roux¹

2014

SA J. An. Sci.

View full text Add to dashboard Cite

The main objection against conventional net energy systems is that owing to variation in gain composition and the different energy contents of protein and fat, the efficiency of energy gain cannot be regarded as a growth constant. The present approach shows that the separate accommodation of protein and fat in predicting ruminant nutritional requirements can easily be achieved, since growth energy retention efficiency can be replaced by protein and fat synthesis efficiencies, together with an augmentation of maintenance with the cost of protein turnover. The synthesis efficiency of protein (k PS) is taken to be k PS = (q L /q M)(6/7), with 6/7 the synthesis efficiency of protein, q L the metabolizability of the diet at an arbitrary level (L) of intake and q M the metabolizability of the diet at maintenance. The correction (q L /q M) allows for the usual evaluation of ruminant diets at the maintenance level of intake. The synthesis efficiency of fat from fermentation of digestible fibre is k FF = 1.018q M or k FF = 1.287k g , without the necessity of adjustment by q L /q M , since evaluation of metabolizability at maintenance is incorporated in the relationship between k FF and q M and where k g denotes growth energy efficiency. Maintenance estimated from fasting heat production or intake at zero energy retention should be augmented by the cost of protein turnover from (PB/6) ÷ (q L /q M), with PB/6 = 102.7 kJ/kg (FW) 0.75 per day for cattle and PB/6 = 78.1 kJ/kg (FW) 0.75 per day for sheep, where PB denotes protein breakdown and FW fasted body mass. Alternatively, with knowledge of the degree of protein maturity, body protein turnover can be incorporated in a theoretically derived estimate of protein retention efficiency. The effective energy system can also be improved by employing theoretical protein retention and fat synthesis efficiencies or by equivalently replacing protein retention efficiency by protein synthesis efficiency in conjunction with the augmentation of maintenance heat production by the cost of protein turnover. A comparison between average growth energy efficiencies shows excellent agreement between estimates of the present theory and those of the UK Agricultural Research Council (ARC) and the US California Net Energy System (CNES), with degrees of maturity together with protein and fat gain ratios that seem typical of original experimental conditions. This implies that the present approach should do at least as well as the ARC or CNES, but can be expected to do better with reasonable accuracy in estimating the degree of protein maturity or maintenance augmentation and the composition of energy gain. The relationship between conventional growth energy efficiency and the synthesis efficiency of fat from digestible fibre allows the accumulated information of net energy systems to be transferable to the new methodology.

show abstract

A family of protein growth curves with extension to other chemical body components together with application to animal nutrition and improvement

Cited by 3 publications

References 25 publications

Use of theoretical efficiencies of protein and fat synthesis to calculate energy requirements for growth in ruminants

Use of theoretical efficiencies of protein and fat synthesis to calculate energy requirements for growth in ruminants

A family of protein growth curves with extension to other chemical body components together with application to animal nutrition and improvement

Use of theoretical efficiencies of protein and fat synthesis to calculate energy requirements for growth in ruminants

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