Prediction of carcass composition, ham and foreleg weights, and lean meat yields of Iberian pigs using ultrasound measurements in live animals1

Abstract

The most valuable lean cuts from Iberian pigs are the hams, forelegs, and loins, which yield high quality cured meat products. This study aimed to assess the correlation between body composition measurements taken in vivo by ultrasonography in Iberian pigs and those taken on the carcass, which were then used to develop predictive models to estimate the weight and yield of these cuts. Before slaughter, 241 Iberian pigs were weighed (slaughter BW) and ultrasonically scanned. Ultrasound images were collected at 3 locations: the 10th intercostal space, caudal to the last rib to image the loin muscle, and the rear gluteal region [ultrasound gluteal backfat (u-GBF)]. After slaughter, the weight of the carcass (CW), ham (HW), foreleg (FW), and loin (LW) were determined, and the sum of these lean cuts weights (CLPW) and the corresponding yields were calculated. A portion of loin with the associated bones, backfat, and skin was obtained by cutting the carcass between the 10th and last ribs and was used to measure, at the 10th (10) and last (14) rib locations, the total backfat thickness, the area of the loin muscle (c-LA), and the thickness of the 4 backfat (BF) layers, namely, the outer (c-OBF), middle (c-MBF), outer plus middle (c-OMBF), and the inner (c-IBF). Finally, intramuscular fat percentages (IMF) were obtained from the meat samples. Corresponding measurements from the ultrasound (u) images were similarly taken at the same 2 ribs (u-BF, u-LA, u-OBF, u-MBF, u-OMBF, and u-IBF). The correlation was greatest between u-MBF10 and c-MBF10 (0.84). Most correlations between ultrasound and carcass measurements were lower at the last rib than at 10th rib. The greatest correlation of IMF10 occurred with u-IBF10 (0.40). Ham weight and HL were more correlated with u-BF10 than with u-BF14 whereas FW was more correlated with u-BF14. The u-LA was more correlated with HW, FW, and LW at the last rib than at the 10th rib. Slaughter live weight accounted for 0.84, 0.42, 0.36, and 0.54% of the variation for the prediction of CW, HW, FW, and CLPW, respectively. The u-LA10 and u-LA14 increased the variation explained by the model up to 0.89, 0.48, 0.39, and 0.62% for CW, HW, FW, and CLPW, respectively. Including u-GBF in the models also increased the R(2) values for predicting HW, LW, HY (ham yield), and LY (loin yield). In conclusion, u-LA10, u-LA14, and u-GBF may improve weight of commercial cuts and yield prediction in live Iberian pigs.

Effects of gender and diet on back fat and loin area ultrasound measurements during the growth and final stage of fattening in Iberian pigs

“…Robinson et al (1987) recorded a correlation of 0.65 between ultrasound back fat at 17 and 20 weeks of age, and McLaren et al (1989) reported moderate to high correlations of live animal ultrasound back fat measured throughout the nursery, grower and finisher stages to carcass back fat at slaughter. In line with the results of previous work on Iberian pigs (Ayuso et al, 2013), the highest correlation coefficients were recorded for the middle layer, followed by the outer and inner layers. This could be attributed, as indicated by these authors, to the lower accuracy in the measurement of the inner layer depth due to a wide variation in loin shape.…”

“…Measurements of thickness of subcutaneous adipose tissue are useful for monitoring the production process in order to optimize growth and carcass composition. These measurements can be obtained using ultrasound techniques, the use of which has become widespread for the Iberian pig in recent decades either for descriptive studies or to predict carcass composition (Ayuso et al, 2013). Likewise, these measurements can be very useful in improving the response of genetic selection in economic traits (Moeller et al, 1998).…”

Ibérico (Iberian) Pig

“…The back fat thickness values measured in all considered studies spanned from 35 to 90 mm on the withers (in average 85 mm in studies with final body weight above 100 kg [55,62,85]), from 10 to 90 mm at the level of the last rib (in average 58 mm in studies with final LW above 100 kg [25, 29-31, 34, 35, 37-44, 46, 51, 52, 55, 64, 65, 68, 69, 76, 77, 82, 85, 86]) and from 48 to 65 mm when measured above gluteus medius muscle (in average 56 mm in studies final body weight above 100 kg [68,76]). Similarly, muscularity measured as loin eye area span from 13 to 29 cm 2 (in average 23 cm 2 in studies with final LW above 100 kg [30,31,34,35,65,76,82]) and muscle thickness measured at the cranial edge of gluteus medius muscle from 11 to 60 mm (in average 40 mm in studies with final body weight above 100 kg [68,76]). Percentage of lean meat content is not reported in the literature as this is not commonly estimated on Iberian pig carcass composition studies, which are focused mainly in the premium cuts obtained from these animals (hams, shoulders and loins).…”

From phenotyping towards breeding strategies: using in vivo indicator traits and genetic markers to improve meat quality in an endangered pig breed

“…In pigs, ultrasound measurements are mostly used to measure backfat and loin muscle depth in living pigs, or to determine correlations between ultrasound measurements and carcass composition (e.g. Ayuso et al, 2013). Using in vivo ultrasound measurements from highly correlated traits (e.g.…”