POSSIBILITIES OF DETERMINING THE PORTION OF LEAN MEAT IN THE SIDES OFPORK

Sets of gilts and young boars of these breeds were evaluated: Large Wh ite (BU), Landrace (L), Prestice Black-Pied (PC), Hampshire (H), Duroc (D) and paternal synthetic lines 98 (SL 98). The evaluated animals un derwent progeny tests, a fattening test started at 30 kg of liveweight and it lasted 130 +/- 3 days. An SVP complete feed mixture (16.70 % d igestible crude protein, 74.2 % total digestible nutrients) was admini stered in a semi-ad-libitum regime. These indicators were determined o n a FOM apparatus within 30 minutes post mortem: backfat thickness at Point I, backfat thickness and the thickness of musculus longissimus d orsi at point II (Fig. 1). The FOM apparatus was also used to determin e the portion of lean meat while applying a determinative equation use d in the FRG. After 24 hours the left side of pork was divided into ba sic cuts (Fig. 2). A detailed analysis of the side of pork included sl aughter cuts 2 to 9, in which the portions of lean cuts were determine d after the method described by Sack (1982), together with the portion s of fat, bones, skin and ligaments. The input data were focused on fo llowing particularly the portion of lean meat in the cold side of pork , portion of lean meat determined on the FOM apparatus while applying the German equation, and the portion of main lean cuts, that means of ham, loin, sparerib and shoulder in the cold side of pork. The portion of lean cuts in the side of pork determined by the detailed analyses reached the value of 46.63 +/- 0.362 % in the whole set (Tab. II). The L breed had the highest meatiness of the maternal breeds, 47.00 +/- 0 .796, followed by the BU breed, 46.29 +/- 0.633, and the lowest portio n of lean cuts was observed in the PC breed (43.47 +/- 1.836 %). The H breed had the best results of paternal breeds (48.43 +/- 0.696), foll owed by the SL 98 line (46.91 +/- 0.855), and the D breed had the lowe st results (45.92 +/- 0.961 %). A relationship between the portion of lean meat (y) determined by the detailed carcass dissection and the po rtion of main lean cuts (x) is documented by the correlation coefficie nt r = 0.89. The application of linear regression enables to estimate the portion of lean meat, namely y = -8.426 + 1.2 x. The results obtai ned on the FOM apparatus while the equation from the FRG was applied w ere somewhat underestimated as to the portion of lean cuts in the whol e set; the undervaluation made 2.05 % in comparison with the detailed carcass analysis. The undervaluation for the different breeds made 0.8 4 to 2.92 %. Hence it is obvious that it will be necessary to derive a determinative equation for commercial types of slaughter pigs kept in the Czech Republic.