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.

Twenty-four extensively reared Iberian pigs were used to study the influence of fattening period length (30, 60 or 90 days) on the fatty acid profiles of intramuscular and subcutaneous fat and the relationships between both profiles. Regarding fatty acid (FA) percentage, PUFA was greater in backfat and MUFA was greater in intramuscular fat (IMF), regardless of fattening period length. The longer fattening period increased MUFA content in backfat (which had a more marked change in oleic acid) and decreased PUFA content in backfat and IMF, but it did not affect SFA content. Within the three-layer subcutaneous backfat, SFA content was greater in the inner layer, MUFA was greater in the outer layer and PUFA was greater in both of these layers. The few differences in FA composition between both adipose tissues suggest that the changes due to the feeding regime are slow and, therefore, although the length of the fattening phase was increased, the fatty acid profile did not change substantially. The strong relationship between the FA profiles of IMF and backfat might be used to predict one profile from the other one when the latter is more readily available for sampling or analytical reasons.

No abstract

Twenty-four Iberian castrated male pigs were used to characterize and evaluate the effect of the duration of "Montanera" in the adipocytes size and its relation with the backfat thickness and intramuscular fat. The animals were fed under extensive conditions during 30, 60 and 90 days in the "Dehesa" before slaughtered. Carcass weight, percentage of intramuscular fat, thickness of backfat and its three layers and adipocytes size of the intramuscular fat were obtained. The group which expended 90 days on fattening obtained the highest adipocytes, with an area higher by a 50% than those that only expended 30 days. The differences in diameter and perimeter adipocyte were not as marked as area. A significant positive correlation between the diameter, area and perimeter of adipocyte with the backfat thickness were found. The fat cells in Iberian pig hypertrophy during the "montanera stage", being this increase significant from month to month in this period of fattening. Also, this adipocyte increase is correlated with the animal weight. The correlation between adipocyte size and inner layer of backfat shows that the inner layer obtained in live pig by ultrasound techniques could be a good marker of fat infiltration in pigs fattening in "montanera" system.

Twenty-four extensively-reared Iberian pigs were used to study the influence of fattening period length (30, 60 or 90 days) on the fatty acid profiles of intramuscular and subcutaneous fat and the relationships between both profiles. Regarding fatty acid (FA) percentage, PUFA was greater in backfat and MUFA was greater in intramuscular fat (IMF), regardless fattening period length. The longer fattening period increased MUFA content in backfat (which had a more marked change in oleic acid) and decreased PUFA content in backfat and IMF, but it did not affect SFA content. Within the 3-layers subcutaneous backfat, SFA content was greater in the inner layer, MUFA was greater in the outer layer and PUFA was greater in both of these layers. The few differences in FA composition between both adipose tissues suggest that the changes due to the feeding regime are slow and, therefore, although the length of the fattening phase was increased, the fatty acid profile did not change substantially. The strong relationship between the FA profiles of IMF and backfat might be used to predict one profile from the other one when this latter was more readily available for sampling or analytical reasons.