Chemical composition of growing pigs and its relationship with body tissue composition assessed by X-ray-computed tomography1,2

Abstract

Ninety hybrid (mainly Large White × Landrace) pigs from 2 experimental replicates were used to study the potential use of computed tomography (CT) as a nondestructive technology for estimating the chemical body composition of growing pigs. Body tissue components (lean, fat, and bone) of 6 live pigs from each sex (boars, gilts, and barrows) were assessed by CT imaging before slaughter at approximately 30, 60, 90, 120, and 150 kg of BW. After slaughter, the empty body components were ground and frozen until analyzed for protein, lipid, ash, and moisture content. Several growth functions were evaluated and the allometric function (Y = aBW(b)), which was evaluated as log(10)chemical component weight = b(0) + b(1)log(10)BW, provided the best fit to the data. For each sex, the allometric coefficient (b(1)) for protein (0.92 to 0.99) was close to but less than 1; for ash (1.03 to 1.12), it was close to but greater than 1; for moisture (0.82 to 0.86), it was less than 1, and for lipid (1.61 to 1.71), it was greater than 1. Deposition rates (change in component weight per unit change in BW) for each chemical component were predicted using derivatives of the function. The mean deposition rates for protein and lipid were 0.141 and 0.286 kg/kg of BW gain, respectively. The deposition rate for protein was generally stable across different BW, whereas that for lipid increased as BW increased. In addition, linear, quadratic, exponential, and logistic functions were fitted to the data to study the relationship between the CT data and chemical components. The linear function was assessed to be the best equation, based on the Bayesian information criterion. The prediction equation for protein (kg) = -1.64 + 0.28 × CT lean (kg), and for lipid (kg) = -0.69 + 1.09 × CT fat (kg), had R(2) values of 0.924 and 0.987, respectively. Sex had no effect (P > 0.05) on the prediction of protein and lipid. The effect of BW was not significant (P > 0.05) for the prediction of lipid, but it was significant (P > 0 0.05) for the prediction of protein. However, the addition of BW to the base prediction equation for protein resulted in an increase of only 0.013 in the R(2) value. It was concluded from this study that CT scanning has great potential as a nondestructive technology for estimating the physical and chemical body composition of pigs. Additional research is required to validate the utility and accuracy of the prediction equations.

Predicting the carcass chemical composition and describing its growth in live pigs of different sexes using computed tomographys

“…The allometric coefficients obtained in this study are in line with the allometric growth of dissectible fat, lean and bone tissues estimated in the same animals , with coefficients >1 for fat tissue, close to 1 for lean mass and <1 for bone. In addition, our results are in agreement with those obtained by Schinckel et al (2008) and Arthur et al (2011) for protein, fat, moisture and ash. Comparisons of mineral growth are difficult because little information has been found in growing pigs.…”

“…The available studies in the literature have focused on predicting the main carcass chemical components, but little is known about the prediction of the mineral content. More recently, Arthur et al (2011) presented equations for predicting the protein, fat and ash content in vivo using CT. These authors showed accurate models for fat and protein (R 2 = 0.98 and 0.92, respectively) and less accurate for the ash content (R 2 = 0.69).…”

“…Previous studies have reported differences among boars, gilts and barrows in the growth of chemical components (Schinckel et al, 2008;Arthur et al, 2011). The use of immunocastrated males is increasing in some countries as an alternative to surgical castration, although the chemical composition and growth of this type of male have not yet been completely explored.…”

“…Previous studies have proven that CT is a suitable method to estimate body composition in live pigs (Szabo et al, 1999;Font-i-Furnols et al, 2015) and carcasses (Font i Furnols et al, 2009). Szabo et al (1999) and Arthur et al (2011) showed the potential of this technology to measure the main chemical body components, but information on the relationship between CT and chemical composition is still limited. Moreover, to our knowledge, there are no studies focused on predicting specific mineral components.…”

An Update on the Pathogenesis of Osteochondrosis

“…55,119 It is therefore feasible to use CT to screen for lesions of osteochondrosis. To be useful in selection, quantification of lean tissue must be carried out at a standardized body weight, 6 usually 120 kg. Screening for osteochondrosis would therefore also be limited to scanning at a standardized body weight.…”