The aim of the present work was (1) to study the relationship between cross-sectional computed tomography (CT) images obtained in live growing pigs of different genotypes and dissection measurements and (2) to estimate carcass composition and cut composition from CT measurements. Sixty gilts from three genotypes (Duroc × (Landrace × Large White), Pietrain × (Landrace × Large White), and Landrace × Large White) were CT scanned and slaughtered at 30 kg (n = 15), 70 kg (n = 15), 100 kg (n = 12) or 120 kg (n = 18). Carcasses were cut and the four main cuts were dissected. The distribution of density volumes on the Hounsfield scale (HU) were obtained from CT images and classified into fat (HU between −149 and −1), muscle (HU between 0 and 140) or bone (HU between 141 and 1400). Moreover, physical measurements were obtained on an image of the loin and an image of the ham. Four different regression approaches were studied to predict carcass and cut composition: linear regression, quadratic regression and allometric equations using volumes as predictors, and linear regression using volumes and physical measurements as predictors. Results show that measurements from whole animal taken in vivo with CT allow accurate estimation of carcass and cut composition. The prediction accuracy varied across genotypes, BW and variable to be predicted. In general, linear models, allometric models and linear models, which included also physical measurements at the loin and the ham, produced the lowest prediction errors.
Image techniques are increasingly being applied to livestock animals. This paper overviews recent advances in image processing analysis for live pigs, including ultrasound, visual image analysis by monitoring, dual-energy X-ray absorptiometry, magnetic resonance imaging and computed tomography. The methodology for live pigs evaluation, advantages and disadvantages of different devices, the variables and measurements analysed, the predictions obtained using these measurements and their accuracy are discussed in the present paper. Utilities of these technologies for livestock purposes are also reviewed. Computed tomography and magnetic resonance imaging yield useful results for the estimation of the amount of fat and lean mass either in live pigs or in carcasses. Ultrasound is not sufficiently accurate when high precision in estimating pig body composition is necessary but can provide useful information in agriculture to classify pigs for breeding purposes or before slaughter. Improvements in factors, such as the speed of scanning, cost and image accuracy and processing, would advance the application of image processing technologies in livestock animals.
Knowledge of tissue and cuts growth depending on the sex could be used to improve performance and efficiency. Computed tomography (CT) is a non-invasive technology that enables the study of the body composition of live animals during growth. The aims of the present study were (1) to evaluate variation in the body composition of four sex types (SEX) of pigs (castrated males (CM), immunocastrated males (IM), entire males (EM) and females (FE)) at the live weight of 30, 70, 100 and 120 kg, assessed using CT; (2) to model the growth of the main tissues and cuts; and (3) to predict the mature BW (MBW) of the four SEX and establish the relationships between the growth models and the MBW. There were significant phenotypic differences in the allometric growth of fat and lean among SEX. For the lean tissue, FE and EM showed higher values of the b coefficient than CM and IM (1.07 and 1.07 v. 1.00 and 1.02, respectively) all of them close to unity, indicating a proportional growth rate similar to live weight and that this tissue developed faster in FE and EM than in CM and IM. However, these differences were not related to differences in estimated MBW. There were significant differences in estimated MBW among SEX, being higher in IM and EM than in CM and FE (303 and 247 v. 219 and 216 kg), however, the MBW may have been overestimated, especially for the IM. The poorer accuracy of the MBW estimate for the IM could be due to a maximum live weight of 120 kg in the experiment, or to the fact that this particular SEX presented two clear behaviours, being more similar to EM from birth to the second injection of the vaccine (130 days) and comparable with CM from that point to the final BW.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.