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      Estimating body composition using CT scans of cross-bred lambs fed at 2 feeding levels and 2 stages of maturity to inform predictive growth models

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          Abstract

          Livestock producers would benefit from more precise predictions of the growth response from nutrients consumed. Previously published models are often limited by the realities of data collection and are unable to account for alterations to body composition, due in part to the response of visceral organs to an alternate diet. The computerized tomography ( CT) scanning of lambs enables the analysis of changes in body composition of individual animals over time, potentially supporting better model development and testing. The aim of this experiment was to develop a repeatable method for the analysis of live lamb body composition using CT scans. A secondary aim was to compare the data collected from CT scanning during a feeding trial to 2 predictive lamb growth models. Cross-bred lambs were fed 2 feeding levels at 2 stages of maturity, with CT scans at the beginning and end of each 8-wk feeding period. The CT scan-derived values for body composition taken at the beginning of feeding periods were used as inputs for 2 existing lamb growth models. Predictions of body composition were compared with CT scan-derived values at the end of feeding periods. The CT scan analysis method used a proportion of images from each lamb to reduce manual image editing. The method was developed by comparing the estimated mass and volume of empty body components using all available CT scans to estimated values using a reduced number of scans from 12 lambs. The CT scan-derived lean tissue mass aligned with model predictions at the end of each feeding period, however, CT scan-derived fat mass was greater than predictions by both models especially for the high feeding level at the later stage of maturity. These results highlight that the analysis of body composition using CT scans requires further validation, particularly for the viscera, and that models likely require refinement to better predict the efficiency of energy utilization by different tissues. The use of live animal CT scans can provide more accurate predictions of the growth of saleable products than measuring liveweight alone and will enable ruminant growth models to better adapt to different genetics and changing diets than comparative slaughter. To replicate the current data using comparative slaughter would require 4 times the animals, as individual lambs were CT scanned 4 times in this study, demonstrating the potential value of CT scanning in live animal research.

          Abstract

          Tracking changes in individual animal body composition over time increases the availability of data to better inform and develop predictive lamb growth models. The computerized tomography scanning of lambs was used to compare changes in body composition to model predictions during a feeding trial.

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          OsiriX: an open-source software for navigating in multidimensional DICOM images.

          A multidimensional image navigation and display software was designed for display and interpretation of large sets of multidimensional and multimodality images such as combined PET-CT studies. The software is developed in Objective-C on a Macintosh platform under the MacOS X operating system using the GNUstep development environment. It also benefits from the extremely fast and optimized 3D graphic capabilities of the OpenGL graphic standard widely used for computer games optimized for taking advantage of any hardware graphic accelerator boards available. In the design of the software special attention was given to adapt the user interface to the specific and complex tasks of navigating through large sets of image data. An interactive jog-wheel device widely used in the video and movie industry was implemented to allow users to navigate in the different dimensions of an image set much faster than with a traditional mouse or on-screen cursors and sliders. The program can easily be adapted for very specific tasks that require a limited number of functions, by adding and removing tools from the program's toolbar and avoiding an overwhelming number of unnecessary tools and functions. The processing and image rendering tools of the software are based on the open-source libraries ITK and VTK. This ensures that all new developments in image processing that could emerge from other academic institutions using these libraries can be directly ported to the OsiriX program. OsiriX is provided free of charge under the GNU open-source licensing agreement at http://homepage.mac.com/rossetantoine/osirix.
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            The superior efficiency of systematic sampling at all levels in stereological studies is emphasized and various commonly used ways of implementing it are briefly described. Summarizing recent theoretical and experimental studies a set of very simple estimators of efficiency are presented and illustrated with a variety of biological examples. In particular, a nomogram for predicting the necessary number of points when performing point counting is provided. The very efficient and simple unbiased estimator of the volume of an arbitrary object based on Cavalieri's principle is dealt with in some detail. The efficiency of the systematic fractionating of an object is also illustrated.
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                Author and article information

                Contributors
                Journal
                J Anim Sci
                J Anim Sci
                jansci
                Journal of Animal Science
                Oxford University Press (US )
                0021-8812
                1525-3163
                2024
                30 July 2024
                30 July 2024
                : 102
                : skae216
                Affiliations
                Fred Morley Centre, School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University , Wagga Wagga, NSW 2650, Australia
                Gulbali Institute, Charles Sturt University , Wagga Wagga, NSW 2650, Australia
                CSIRO Agriculture and Food , Black Mountain, ACT 2600, Australia
                Fred Morley Centre, School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University , Wagga Wagga, NSW 2650, Australia
                Gulbali Institute, Charles Sturt University , Wagga Wagga, NSW 2650, Australia
                Fred Morley Centre, School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University , Wagga Wagga, NSW 2650, Australia
                Gulbali Institute, Charles Sturt University , Wagga Wagga, NSW 2650, Australia
                NSW Department of Primary Industries, Livestock Industries Centre, University of New England , Armidale, NSW 2351, Australia
                Author notes
                Corresponding author: thomas.keogh@ 123456csiro.au
                Author information
                https://orcid.org/0000-0002-9500-5933
                https://orcid.org/0000-0003-1783-1049
                Article
                skae216
                10.1093/jas/skae216
                11347783
                39078937
                af170b93-3371-4fea-9b16-d5033f93b881
                © The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 11 December 2023
                : 28 July 2024
                : 27 August 2024
                Page count
                Pages: 15
                Categories
                Ruminant Nutrition
                AcademicSubjects/SCI00960

                body composition,growth,modelling,nutrition,ruminant
                body composition, growth, modelling, nutrition, ruminant

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