TISSUE PERCENTAGES IN THE SIDE OF PORK OF PIG BREEDS RAISED IN THE CZECH-REPUBLIC

In the process of breeding and in the course of application of differe ntiated selection in maternal and paternal breeds of pigs it is necess ary to determine in certain time intervals how the selection criteria influenced the carcass composition. Therefore we focused our investiga tions on acquisition of detailed information about the percentages of the tissue in the carcass of the pig breeds raised in the Czech Republ ic. The investigations involved sets of gilts and barrows of the breed s Large White (LW, n = 46), Landrace (L, n = 27), Prestice Black-Pied (Pc, n = 14), Hampshire (H, n = 39), Duroc (D, n = 43) and Czech Meat Pig (CVM, n = 38). The investigated animals were included in a pig pro geny test from 30 kg live weight of pigs, the test at a pig progeny te sting station lasted 130 +/- 3 days. The average weight of the dressed side of pork was 46.63 +/- 0.412 kg. The side of pork of each animal was cut as usual in slaughterhouses, and the percentages of muscle, fa t, bones, skin and other tissues comprising tendons, lymphatic glands, veins, arteries, etc. were determined in the cuts by detailed carcass analysis. As the carcass parts such as head and trotters contain a hi gh percentage of bones and their dissection would be difficult, they w ere not subjected to detailed analysis. All these parts were included in bones, hence it is necessary to assess the results with respect to this fact. The input data were processed by a linear model. The detail ed carcass analyses provided information on the percentage of the part icular tissue in the dressed sides of pork. The percentage of muscle i n the side of pork had the value 47.17 +/- 0.244 in the whole investig ated set. This value according to the breeds was highest in the Hampsh ire breed (48.54 +/- 0.559% of muscle), followed the Landrace breed (4 8.26 +/- 0.685%). The average value was determined in the Large White breed (47.84 +/- 0-541%) and in the Czech Meat Pig (47.60 +/- 0.568%). The Duroc and Prestice Black-Pied breeds had somewhat lower values (4 5.28 +/- 0.637% and 43.25 +/- 0.975%, respectively). The percentage of fatty tissue had the average value of 30.84 +/- 0.285% in all breeds. The lowest percentage of fat was found out in the Landrace breed (29. 45 +/- 0.800%). The order of the other breeds was in fact opposite to the trend in the percentage of muscle. The correlation coefficient bet ween the percentage of muscle and fat was r = -0.97 and between the pe rcentage of muscle and bones r = 0.54. A high negative relationship wa s determined between the percentage, of fat and bones (r = -0.72).