Differential growth and development of pigs as assessed by X-ray computed tomography1,2

Abstract

Data from 54 hybrid (mainly Large White x Landrace) pigs (18 boars, 18 gilts, and 18 barrows) were used to quantify and mathematically describe the differential growth and development of body components of live pigs. The pigs were 32.4 +/- 3.2 kg of BW and 70 +/- 1 d of age (mean +/- SD) at the beginning of the study, were individually penned and fed ad libitum, and were weighed weekly. Computed tomography (CT) imaging was used to determine the weights of lean, fat, bone, and skin tissue in the live pig at 30, 60, 90, 120, and 150 kg of BW. For each target BW, the sum of all the weights of the body components, as assessed by CT, was referred to as CT BW. Linear and nonlinear models were developed to evaluate the patterns of growth and development of each body component relative to CT BW. The correlation between the actual BW and CT BW was close to unity (r = 0.99), indicating that CT scanning could accurately predict the BW of pigs. Across sex and castrate status, percentage of fat (fat weight/CT BW) in the pig was least (11.2%) at the 30-kg target BW and continued to increase to 22.6% by the 150-kg target BW. Percentage of lean, however, was greatest (67.2%) at the 30-kg target BW and continued to decrease to 53.4% by the 150-kg target BW. The sex or castrate status x target BW interaction was significant (P < 0.05) for all the body components, indicating that the developmental patterns were different among sex or castrate status. Barrows were fatter relative to gilts, which in turn were fatter than boars. For lean, the observed pattern for sex or castrate status differences was opposite that for fat. To predict responses to management strategies on growth and development in pigs, accurate mathematical models are required, and the results of this study indicate that the nonlinear (e.g., augmented allometric and generalized nonlinear) functions provided better descriptions of the growth and development of most body components of the live pig than did the simpler (e.g., linear and allometric) models.

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

“…Ltd., Smithfield, New Sonth Wales, Australia) and ketamine (Ketamil, 100 mg/niL; Ilium Veterinary Products, Troy Laboratories Pty. Ltd.; Giles et al, 2009) and scanned by CT close to that BW. On the day after CT scanning, each of the pigs was weighed and anesthetized with an intravenous dose of barbiturate (Lethabarb containing 325 mg/niL of pentobarbitone sodinm, Virbac Pty.…”

“…In a review by Szabo et al (1999), the common imag-3935 ing techniques used for estimating the body composition of live pigs and carcasses were evaluated, and CT scanning was found to be the most accurate. The differential (allometry, or changes in proportions of body tissues), as well as the temporal (changes in size over time) growth and development of body tissues (lean, fat, and bone) of live pigs, have been quantified and mathematically described using CT scan data in studies by Giles et al (2009) and Barchia et al (2010), respectively. The ultimate goal is to be able to describe the growth and development of the chemical composition of pigs.…”

Imaging technologies to study the composition of live pigs: A review

“…The information from the 1100 slices per potential breeding boar is processed to determine body composition phenotypes such as lean meat, fat, bone, primal cuts, live and carcass weight (Scholz et al, 2015). Giles et al (2008) used CT to study the differential growth and development of pigs and determined that differences in the weights of body components by sex were minimal at the starting 30 kg target BW but increased with increasing target BW (up to 150 kg).…”

“…Kolstad (2001) used azaperon (4 mg/kg live weight -LW) followed by phentotal sodium (5 mg/kg LW). Giles et al (2008) used Yohimbine (10 mg/ml), and Carabús et al (2015a) sedated animals intramuscularly with azaperon (0.1 mg/kg body weight -BW) and anaesthetised them with ketamine (0.2 mg/kg BW) and propofol (0.22 mg/kg BW, intravenously in the ear). Propofol was only administered at heavy weights.…”

Modeling of pig growth by S-function – least absolute deviation approach for parameter estimation

“…Traditionally, the changes of body composition during growth are studied using the methods such as dissection of the carcass, computed tomography, magnetic resonance imaging and some other useful techniques at varying age or body weight (Giles et al 2009). It is a complex problem, especially when it comes to a modelling of the growth patterns.…”