Longitudinal changes in ultrasonic measurements of body composition during growth in Suffolk ram lambs and evaluation of alternative adjustment strategies for ultrasonic scan data

Abstract

Four equations were used to compare alternative procedures to adjust ultrasonic estimates (y) of backfat thickness (BF) and LM area (LMA) for BW using data from a series of 7 scans on 24 Suffolk ram lambs born in 2007. Equations were linear, linear + quadratic, allometric (y = αBW β ), and allometric + BW (ABW; y = αBW β e γW ). Goodness of fit was very similar between equations over the range of the data. Resulting adjustment equations were tested using 3 serial scans on winter-born Suffolk (n = 150), Hampshire (n = 36), and Dorset (n = 43) rams and 52 fall-born Dorset rams tested at the Virginia Ram Test in 1999 through 2002. Partial correlations (accounting for the effect of year) between predicted and actual measures ranged from 0.78 to 0.87 for BF and 0.66 to 0.93 for LMA in winter-born rams and from 0.70 to 0.71 for BF and 0.72 to 0.78 for LMA in fall-born rams. No significant differences in predictive ability existed between equations for BF or LMA (P > 0.05), and there was no indication that the allometric equation was a better predictor than linear within the range of the data. Adjustment equations were also tested using serial scan data from 37 Suffolk ewe lambs born in the same contemporary group as the rams used to derive the prediction equations but fed for a substantially slower rate of BW gain. Correlations between predicted and actual values of BF and LMA indicated lambs were too young and small at the first scan (77 d, 32.4 kg) to reliably predict carcass measures at typical slaughter weights. For prediction using data from the 2 subsequent scans, at mean ages >96 d and mean BW >39 kg, correlations between predicted and actual values were 0.72 to 0.74 for BF and 0.54 to 0.76 for LMA. Little difference existed between equations for predicting BF. For LMA, the ABW form was a weaker predictor than the others, and the linear equation was slightly superior to allometric. Therefore, it appears the linear and allometric forms are both suitable for use in central ram test and performance-tested farm flocks.

Real-time ultrasound (RTU) imaging methods for quality control of meats

“…In recent years, several works have been published that clearly show that the RTU technique allows good estimates of the composition of the carcass to be obtained. These studies aimed to predict carcass composition in adult animals (Hopkins et al ., 2007;Teixeira et al ., 2008), market lambs Leeds et al ., 2008;Orman et al ., 2008;Thériault et al ., 2009;Emenheiser et al ., 2010;Orman et al ., 2010) or light carcasses (Ripoll et al ., 2009). Although the results obtained were generally good, attention must be paid to the factors that lead to inaccuracy in the RTU technique when used for small ruminants.…”

“…Subcutaneous fat depth above the LTL muscle and muscle depth and area are the parameters usually measured in RTU examinations. A large number of studies (McEwan et al ., 1989;Silva et al ., 2006a;Teixeira et al ., 2006;Hopkins et al ., 2007;Silva et al ., 2007a;Leeds et al ., 2008;Teixeira et al ., 2008;Thériault et al ., 2009;Emenheiser et al ., 2010;Orman et al ., 2010) have found a significant correlation ( r > 0.6; P < 0.01) between both fat and muscle RTU measurements and the corresponding carcass measurements in those regions. The placement of the probe at reference points must be correct, since SFD and LTL muscles vary significantly over short distances either cranio-caudally (Delfa et al ., 1991;Silva et al ., 2007a) or medium-laterally (Simm, 1983;Korn et al ., 2005).…”

“…(2009) Aloka SSD 900; 7.5 MHz Accuracy of RTU measurements and predicting carcass composition Thériault et al . (2009) Ultrascan 50; 3.5 MHz Accuracy of RTU measurements Emenheiser et al . (2010) Aloka 500V; 3.5 MHz Accuracy of RTU measurements Orman et al .…”

Application of longitudinal data analysis allows to detect differences in pre‐breeding growing curves of 24‐month calving Angus heifers under two pasture‐based systems with differential puberty onset

“…Hence the possibility to distinguish changes over time within individuals, from differences among groups in their baseline levels, allows to exclude some variation within treatment from the error term, and this is exploited to draw more powerful inferences. This kinds of longitudinal approach have been used in animals to detect day‐to‐day growth and body composition differences …”

Estimation of meat amount by non-linear multiple regression equations using in vivo and carcass measurements on Teleorman Black Head lambs

“…Silva et al (2006) and Cadavez and Monteiro (2011) used multiple regression equations to predict the composition of Chura, Galega, Bragancana and Suffolk lamb carcasses, using the weight of the warm carcass and the ultrasound parameters (the proportion of subcutaneous fat, the intramuscular fat content, the thickness of subcutaneous fat layer and the bone weight) in order to obtain an objective classification and grading of sheep carcasses. Emenheiser et al (2010) showed the necessity of validating the ultrasound method utilization to determine lamb carcass composition for meat production and showed the advantages of this method. In order to improve the evaluation of the sheep selected for meat production, the purpose of this study was to develop non-linear multiple regression equations to evaluate the amount of carcass meat and the amount of selected cuts in local breed Teleorman Black Head lambs by using carcass and ultrasound measurements of the subcutaneous fat layer thickness, muscle depth, muscle eye area and perimeter of the muscle area of LD muscle.…”