Based on the results of dissections of 126 pig carcasses, the proportions of pork belly and its parts, i.e. belly with bones, belly without bones and tip of belly, were determined. In addition, proportions of lean meat, bones, intermuscular and subcutaneous fat were determined in belly with bones as percentages of the weight before the dissection. Lean meat content of carcass was the most important factor for determining the pork belly composition. The correlation between lean meat content of carcass and lean meat percentage of belly with bones was 0.92 ± 0.035. Sex and slaughter weight had a greater impact on the composition of pork belly than the crossbred combination. The lean meat percentage of belly with bones in gilts was higher by 4.4% than in barrows. For slaughter weights higher than 100 to 110 kg, lean meat content in pig belly decreased with increasing slaughter weight.

ABSTRACT:The objective of the study was to quantify differences in the carcass composition of pig carcasses with different lean meat proportions. Totally 132 carcasses with lean meat proportions ranging from 45 to 65% were analysed. The average lean meat proportion in the analysed set of carcasses was 55.38% (s = 4.319). The carcasses were classified into the groups according to their lean meat proportion (R, 45.0 to 49.9%; U, 50.0 to 54.9%; E, 55.0 to 59.9%; S, more than 60.0%). Carcasses from each group were cut into primal cuts and the main cuts (leg, loin, shoulder and belly with bones) were further separated into different tissues. Carcass value was markedly enhanced by the increasing carcass lean meat proportion. Average leg percentages in the groups R, U, E and S were 17.88% (s = 0.918), 19.32% (s = 0.889), 20.88% (s = 0.817) and 21.88% (s = 0.827), respectively. Average proportions of fat over leg expressed as percentages of leg weight in these groups were 5.82% (s = 0.402), 4.87% (s = 0.556), 4.05% (s = 0.479) and 3.21% (s = 0.321), respectively. Lean meat proportions of leg weight were improved from 84.93% (s = 1.136) in the group R to 88.12% (s = 0.986) in the group S. The most distinct differences were found in lean proportions of belly weight. The observed averages in the group R and S were 43.90% (s = 2.729) and 62.10% (s = 2.219), respectively. Actually, in carcasses with a high classification score the belly can be considered as a cut with the predominant muscle tissue. The results of the study proved the efficiency of carcass evaluation based on the lean meat proportion. Such a method can significantly contribute to the overall improvement of pig production.

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Objective methods of pig carcass classification have been applied in the EU since 1984. The methods of classification used in different member states are laid down by the relevant EU legislation. The classification of pig carcasses is based on the lean meat content predicted on the basis of fat and muscle measurements taken at specific carcass sites. A high correlation to the carcass lean meat content is a fundamental condition for these measurements. The correlation coefficients reported by Branscheid et al. (1987) for fat and muscle thickness measured between the third and fourth from the last rib were r = -0.846 and r = 0.739, respectively. Somewhat lower coefficients r = -0.736 and r = 0.538 for fat and muscle thickness, respectively, were found by Lagin et al. (1995). Hulsegge et al. (1994) assessed the accuracy of the lean meat content in carcasses and in major cuts when using multiple site measurements compared with a single site measurement. They analysed 17 measurement sites and evaluated the accuracy of prediction formulae according to s e . The addition of another measurement to the prediction formulae improved this value by 0.03 to 0.13 percent points. Šprysl et al. (2007) took measurements at six chosen carcass sites using the FOM apparatus. They reported correlations between the lean meat content and muscle and fat measurements taken at different sites.Regression formulae for the prediction of lean meat content are constructed on the basis of the To increase the accuracy of the prediction formulae, additional measures were included in the calculation which reduced s e by 0.48 to 0.54 percent points. The relationships between the lean meat content and other indicators of carcass value were also assessed. The highest correlation coefficient was determined in the ratio of the fat cover area above the musculus longissimus lumborum et thoracis (MLLT) to the MLLT area (r = -0.87). On the contrary, the lean meat content demonstrated the lowest correlation with the cold carcass weight (r = -0.25). Major carcass cuts (ham, loin, shoulder, belly with bones) from the carcasses classified in different SEUROP classes were evaluated. Significant differences between the classes were found in the proportions of cuts without fat cover, fat thickness measured at point "P 2 ", and fat thickness measured on the midline plane separating the left and right sides of the carcass.

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