Computer tomographic investigation of subcutaneous adipose tissue as an indicator of body composition

<p>Abstract</p> <p>Background</p> <p>Modern computer tomography (CT) equipment can be used to acquire whole-body data from large animals such as pigs in minutes or less. In some circumstances, computer assisted analysis of the resulting image data can identify and measure anatomical features. The thickness of subcutaneous adipose tissue at a specific site measured by ultrasound, is used in the pig industry to assess adiposity and inform management decisions that have an impact on reproduction, food conversion performance and sow longevity. The measurement site, called "P2", is used throughout the industry. We propose that CT can be used to measure subcutaneous adipose tissue thickness and identify novel measurement sites that can be used as predictors of general adiposity.</p> <p>Methods</p> <p>Growing pigs (<it>N </it>= 12), were each CT scanned on three occasions. From these data the total volume of adipose tissue was determined and expressed as a proportion of total volume (fat-index). A computer algorithm was used to determined 10,201 subcutaneous adipose thickness measurements in each pig for each scan. From these data, sites were selected where correlation with fat-index was optimal.</p> <p>Results</p> <p>Image analysis correctly identified the limits of the relevant tissues and automated measurements were successfully generated. Two sites on the animal were identified where there was optimal correlation with fat-index. The first of these was located 4 intercostal spaces cranial to the caudal extremity of the last rib, the other, a further 5 intercostal spaces cranially.</p> <p>Conclusion</p> <p>The approach to image analysis reported permits the creation of various maps showing adipose thickness or correlation of thickness with other variables by location on the surface of the pig. The method identified novel adipose thickness measurement positions that are superior (as predictors of adiposity) to the site which is in current use. A similar approach could be used in other situations to quantify potential links between subcutaneous adiposity and disease or production traits.</p

NON INVASIVE METHOD TO STUDY THE BODY COMPOSITION OF RABBITS BY X-RAY COMPUTERISED TOMOGRAPHY

X-ray computerised tomography (CT) techniques for non-invasive and exact study of rabbit body composition are reviewed. The method is fairly accurate in determining total body fat and energy content (R2=0.8-0.9), but less so in predicting total body protein content (R2 =0.4-0.7). lt may be also applied for the in vivo quantitation of valuable meat parts due to correlations (≈0,7) between main carcasa traits and CT data. The rather high cost of examination may be reduced by scanning three rabbits simultaneously, which corresponds 12 to 36 animals per hour. This reduced cost is comparable to that of the whole body chemical analysis or of the progeny test and, unlike the latter, the CT method does not increase the generation interval during selection. Different scanning and evaluating technics may be applied In the selection programa for estimation of carcasa traits, for improving the dressing percentage and to follow the development of important tissues in the same rabbit during the whole growing period.Abstract not available

Non-invasive study of changes in body composition in rabbits during pregnancy using X-ray computerized tomography

The objectives of this study were: 1 ) to follow changes in body composition during pregnancy using a non-invasive method; 2) to compare the results obtained with X-ray computerized tomography (CT) and with the slaughter method; and 3) to study the influence of litter size on changes in body reserves in pregnant does. Seventeen pregnant Pannon White rabbit does were examined by means of CT on the day of insemination, on days 14, 21 and 28 of pregnancy, and a few hours after parturition. At comparable time points, non-pregnant does (n = 26) were also scanned as a control group. During the CT procedure 27 images (scans) were taken from all of the animals in the body region from the scapular arch to the femoral-tibial articulation. The scans were processed by means of the computerized imaging technique, to obtain three-dimensional (3D) histograms that represented the changes in the water content, and in the fat and muscle tissues of the does. On the day after parturition all the does were slaughtered and the fat content of their empty bodies was subjected to chemical analysis. In the first 14 days of pregnancy little change was detected in body composition. Thereafter, in the abdominal region a marked increase was noted in densities corresponding to water and water-rich tissues, in correspondence with the growth of uterine contents. From day 21 of pregnancy a decrease in fat was noted in the pregnant does and an increase in the same reserves in the non-pregnant control group. To compare the fat content of animals in different physiological states so-termed fat indices were created by relating pixels corresponding to fat densities to the total number of pixels. In the same way muscle indices were created to demonstrate the changes in the muscle reserves during the experimental period. To test the accuracy of estimation by fat indices a regression analysis was carried out between the index numbers and the fat content subjected to chemical analysis. The result of this analysis showed a high correlation between the parameters examined. The same fat indices demonstrated a higher mobilisation of body reserves in does with higher litter size than in those with smaller litters

IN VIVO MEASUREMENT OF BODY PARTS AND FAT DEPOSITION IN RABBITS BY MRI

[EN] An experiment using Magnetic Resonance lmaging (MRI) tomography were done inwlving 87 rabbits el four genotypes, 12 or 16 weeks old. MRI was applied on the day before slaughter. The slices were taken in three orthogonal planes. The resufting pictures indicate that MRI provides very detailed slices. The volume of the fat deposit around the kldneys, the tml body fat volume of the body and the muscle el the hind part was collected from the MRI pictures. Correlation coefficients were computad between the volume of the perirenal fat ancl its weight, the muscle volume el the hind part ancl its weight, the tctal body fat volume and the crude fat content. The correlation values were found to be very high (O. n to 0.94) in the group of age 16 proving that the MRI tomograph is a excellent In vivo method to determine the volumes of fat and muscle. The la.ver correlation values in the group el age 12 (0.39 to 0.76) indicate that the MRI tomography is sensitiva to the digital sampling errors.[FR] Un total de 87 laplns appartensnt lt 4 génotypes ~s de 12 lt 16 semalnes ont été étudlés par lmsgerie en résonance magnétique (IRM). Les laplns ont été ana/ysés par IRM Is vei//e de fsbattage. Les "coupes• ont été réalisées dans 3 p/Bns orthogonaux. Les images obtenues pour chaque coupe sont tres détaillées. Le volume de la masse adipeuse p(riénBle, de fensemble des masses adipeuses du COITJS et ce/ui des masses musculaires de farrilJre de fanimal ont été détermlnées par analyse de coupes. Les coefficients de corrélation entre ces volumes détermlnés par IRM et /eur poids mesuré par dissection aprés abattage sont de O, 77 lt 0,94 chez les laplns de 16 semalnes. Ceci atieste que f/RM est une bonne méthode pour la mesure in vivo des volumes de tissu adipeux ou musculaire. Les vBleurs beaucoup plus faibles des corrélations obtenues chez les laplns de 12 semalnes, (0,39 it O, 76) montrent la limite de f/RM pour ce type d'étude (faible masse des tissus adipeux) en raison de se sensibilité aux erreurs d'analyse des images infonnatiques numérlséesThis work was supported by the E.C. (Copernicus) as a part of project CIPA-CT93-0206. The authors gratefully ackowledge E. Biro-Németh, L. Radnai and the staff of the CT Biological Centre of the Pannon Agricultural University for their expert assistanceKöver, G.; Szendrö, Z.; Romvari, R.; Jensen, J.; Sørensen, P.; Milisits, G. (1998). IN VIVO MEASUREMENT OF BODY PARTS AND FAT DEPOSITION IN RABBITS BY MRI. World Rabbit Science. 06(2). doi:10.4995/wrs.1998.349SWORD06