INVESTIGATION OF GENETIC MECHANISMS FOR IMPROVING THE REGULATION OF FEED INTAKE AND NUTRIENT UTILIZATION IN POULTRY
Title: In vivo measurement of body composition of chickens using quantitative magnetic resonance (QMR)and dual x-ray absorptiometry (DXA)
| Mitchell, Alva |
| Rosebrough, Robert |
| Taicher, G - |
| Kovner, I - |
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2011
Publication Date: August 1, 2011
Citation: Mitchell, A.D., Rosebrough, R.W., Taicher, G.Z., Kovner, I. 2011. In vivo measurement of body composition of chickens using quantitative magnetic resonance (QMR)and dual x-ray absorptiometry (DXA). Poultry Science. 90:1712-1719.
Interpretive Summary: During studies of the growth of broiler chickens it is important to be able to accurately assess changes in body composition. Body composition analysis results can be used to monitor and evaluate growth patterns, genetic improvement, dietary treatments, progression of chronic disease, and efficacy of medical interventions. QMR is a nuclear magnetic resonance based method for measuring the fat, lean and water content of the total body of the live animal. The purpose of this study was to evaluate the use of QMR for measuring the body composition of chickens while comparing QMR results to those obtained by dual X-ray absorptiometry (DXA) and chemical analysis. It was found that QMR is a quick and convenient method for measurement of body composition broiler chickens. Without the use of anesthesia, the birds can be measured as frequently as needed without affecting growth. After both were calibrated against chemical analysis, there was good agreement between QMR and DXA for measuring fat, lean, and water content.
QMR is a nuclear magnetic resonance based method for measuring the fat, lean and water content of the total body of the live animal. The purpose of this study was to evaluate the use of QMR for measuring the body composition of chickens while comparing QMR results to those obtained by dual X-ray absorptiometry (DXA) and chemical analysis (CA). A total of 191 birds, were scanned live (non-anesthetized) by QMR, killed, and then scanned by DXA. The birds were Ross 708 broiler chickens and ranged in weight from 786 to 3130 g. In addition, 48 of the carcasses were chemically analyzed for total body lipid, water and ash content.
Compared to CA, QMR underestimated the percentage of total body fat by 34% while DXA overestimated the percentage of fat by 50% (10.35±3.35 by CA vs. 6.73±3.90 by QMR and 15.55±4.01 by DXA, P<0.05). Both QMR and DXA measurements of percentage total body fat were highly correlated with the CA measurement (R2= 0.94 and 0.68, respectively). Both QMR and DXA estimates of total body water were close to the CA measurement (1166±277g by CA vs. 1214±279g by QMR and 1217±255g by DXA, P>0.05), with R2 values of 0.90 and 0.91, respectively.
Based on regression analysis, when prediction equations were applied to the entire group of birds, the QMR and DXA measurements of total body water and total body lean mass were in good agreement, with no significant difference (1125±244g vs. 1135±246g and 1377±3116g vs. 1403±309g, respectively, P>0.05) and highly correlated (R2=0.97 for both). Likewise, the QMR measurement of total body fat agreed closely to that measured by DXA (164±48g vs. 167±47g, respectively) and was highly correlated (R2=0.72).
In conclusion, the results of this study demonstrate that with proper calibration, both QMR and DXA can provide accurate measurements of the body composition of chickens. The major advantage of the QMR method is that no anesthesia is required, thus facilitating the ease of measurement and, as well as, repeated measurements.