Designing Foods Animal Product Options in the Marketplace (1988) / Chapter Skim
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Assessing Body Composition
Assessing Body Composition
Pages 242-277
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From page 242... ...
or carcass analysis of an animal (Lewis et al., 1986; Sheng and Huggins, 1979~. The terms lean body mass (LBM)
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In its simplest form, body mass can be considered to consist of two phases: fat and FFM. In the research setting, body fat content is often determined by deriving FFM from a set of measurements and then calculating body fat content as part of the body mass not accounted for by FFM.
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From page 244... ...
The values of 0.9 for the density of body fat and 1.10 or 1.095 for the density of mixed tissues of the FFM are used in the calculations (Brozek et al., 1963~. Although the density of body fat varies at different body sites and from consumption of different diets, the variations reported are less than 2 percent (Pearson
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formulas for clensitometric estimation of the fat content can be offered." Determination of FFM by Hydrometry A value for body fat may be derived simply from the total body water (TBW) measurement baser]
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Proper calibration of this system has permitted quantification of the K concentration in the human body from which FFM, and hence fat, can be estimated. Total Body Electrical Conductivity and Impedance Total body electrical conductivity (TOBEC)
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More recently, infrared interactance has been proposed as a rapid, safe, and noninvasive method to measure subcutaneous fat in both research and field settings (Conway et al., 1984~. Numerous studies have attempted to validate the extrapolation of subcutaneous fat thickness measured at a number of sites on the body to total body fat and to establish subcutaneous fat thickness as a "standard" for the assessment of total body fat (Durnin and Rahaman, 1967~.
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Sophisticated software allows total body fat to be computed from a series of cross-sectional fat areas along the length of the body. Although all these techniques show great potential in the estimation of body fat, they are expensive and relatively unavailable for routine measurements.
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1986. Measurement of lean body mass and total body fat using dual photon absorptiometry.
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1984. Estimation of total body fat and protein by densitometry.
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, and total bocly electrical conductivity analysis (Harrison and Tan Itallie, 19824. The focus of this report is on total body electrical conrluctivity (TOBEC)
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extracellular water making up the FFB. Electrical conductivity of various biological materials indicates that constituents associated with the FFB (for example, muscle, liver, and blood)
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FFB clerivec] from densitometry, total body water, and/or 40K spectroscopy.
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and total body water (r = 0.98~. Klish et al.
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Body density was measured weighing the subject underwater; pulmonary resiclual volume was measured at the time of weighing (Boileau et al., 1984~. Fat and FFB expressed both in absolute and relative terms were estimatec!
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Total body electrical conductivity analysis appears to be a promising method for assessing body composition on both theoretical and empirical grounds. The association APPENDIX demonstrated between TOBEC and FFB determined by both densitometry and 40K spectroscopy statistically confirms the theoretical basis of the method.
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1983. Comparison in man of total body electrical conductivity and lean body mass derived from body density: Validation of a new body composition method.
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Therefore, this paper identifies the various techniques that have been used to estimate body composition, as well as new techniques that have potential for future application. LINEAR MEASUREMENTS OF LIVE ANIMALS Some years ago, some livestock evaluators believed that measurements of the length, width, height, and circumference of live animals could be used to predict various carcass characteristics inclucling composition (Busch et al., 1969; Cook et al., 1951; Green et al., 1969; Kidwell, 1955~.
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From these early studies have come more than 200 papers relating linear measurements of body fat thickness and longissimus dorsi area to the muscle, fat, and bone percentage of the carcass as well as to its chemical fat, protein, and water content (see, for example, Berg and Butterfield, 1976; Breidenstein et al., 1968; Brozek, 1961; Cross, 1982; Doornenbal, 1968; Kauffman, 1971; Kempster, 1986; Zobrisky, 1963~. The relationships of back fat thickness and size of the longissimus dorsi are considered to be good, but not excellent, predictors of body composition.
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LIVE WEIGHT The development of growth curves from the animal's live weight provides a practical and simple method for estimating body composition if the genetic history for bocly composition is known. As animals grow, APPENDIX their carcass composition changes and the proportion of fat increases at the expense of muscle and bone (Rouse et al., 1970~.
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After live estimates were statistically compared with carcass measurements, the coefficients of determination of either a weight-adjusted or a weight-unadjuste(1 basis indicatecl that trained personnel could account for more than half of the variation in carcass traits ant] that their estimates account for, on the average, over 26]
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No clear differences were detected for the other four units between the machine-operator combinations in terms of predicting body composition traits. Although the Philips and Ohio machines were only able to scan a section of the longissimus dorsi muscle and its overlying subcutaneous fat, they provided an acceptable description of the car- anatomy and carcass composition; APPENDIX cass composition traits.
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From page 263... ...
Potassium is not found in fat in any significant amount, and therefore, if potassium is present in the fat-free tissue as a constant percentage, then a value for total body potassium can be converter] to a weight of lean body mass (Ward, 1968~.
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A1though this would appear to be a simple procedure, it is not, especially in live animals. Even water displacement, which is the simplest method, has numerous pitfalls.
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for specific gravity in predicting carcass fat. The variation in predicting carcass composition in pork carcasses is similar to that for cattle ant!
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used the D2O procedure to estimate body fat content in sheep. The values they obtained differed
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It is relatively simple for scientists to use but too complex for industrial application. It is a good way to estimate total body water but is limited in its level of accuracy for total body fat.
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SUMMARY OF THE PRACTICABILITY/ COST-BENEFIT COMPARISON OF BODY COMPOSITION MEASURES More than 30 techniques for estimating live animal or carcass composition were
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III. Effect of energy intake upon carcass composition.
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1970. The use of deuterium oxide space to determine the amount of body fat in pregnant blackface ewes.
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1949. Relationship of body specific gravity to body fat and water content.
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1974. Evaluation of a tissue-sawdust technique for predicting beef carcass composition.
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W EIGHT Beyonc! a live weight of about 90 kg, the rate of lean tissue deposition reaches a plateau and, in many pigs, actually declines as fat deposition increases.
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Grain Source The two most commonly fed grain sources for pigs are corn and barley. Corn is better than barley in terms of performance criteria, but barley is superior to corn with regard to carcass measurements (Greer et al., 1965~.
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Growth Hormone Daily injections of porcine growth hormone by Machlin (1972) have been shown to improve daily gain, feed efficiency, and carcass measurements.
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1968. Effect of caffeine on nitrogen retention, carcass composition, fat mobilization and oxidation of Ci4-labeled body fat in pigs.
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1986. Immunological manipulation of body fat.
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