THE EFFECT OF INTENSIVE SELECTION AND NUT RITION ON FATTENING PERFORMANCE AND CARCASS VALUE OF HYBRID PIGS

Experiments were focused on analysis of indicators of fattening perfor mance, carcass value and meat quality in new-bred hybrid crosses in th e conditions of Slovakia. Selection for the above indicators started i n mothers of the terminal hybrid when gilts that had reached the weigh t of 100 kg at the age of 173 days and in vivo meat percentage of 53.2 (using a PIGLOG 105 apparatus) were included in the stock herd of a c ommercial farm. Sibs and/or half-sibs of mothers of the terminal hybri d of the new-bred hybrid cross had daily weight gain of 815 g, percent age of valuable lean cuts 51.19% and eye-muscle area 39.20 cm(2) in te st conditions. Fathers of the terminal hybrid (specifically selected m eat line) showed daily weight gain of 871 to 884 g, percentage of valu able lean cuts 53.0 and eye-muscle area 41.7 to 42.4 cm(2) under test conditions. The hybrids received three kinds of feed mixes with differ ent contents of digestible protein substances (11.1, 13.9 and 15.2%), lysine (0.57, 0.73 and 0.85%) and energy (12.7, 12.9. and 13.1 IU ME) in the course of fattening trials. Under approximately the same condit ions of external environment, at sex parity and average slaughter weig ht of about 110 kg the new-bred hybrids receiving the different feed m ixes showed the following figures: percentage of lean cuts (neck, shou lder, loin and ham) amounting to 49.58, 50.92 and 51.55, respectively, percentage of meat from ham (in the weight of the side of pork) 19.92 , 20.40 and 20.56, resp. percentage of meat from ham and loin 30.05, 3 1.20 and 31.28, resp. and eye-muscle area 39.61, 40.14 and 40.19 cm(2) , resp. The percentage of lean meat content ante mortem and/or post mo rtem was 55.27 and/or 56.85, the percentage of fatty parts (separable fat from valuable lean cuts + kidney fat) in the weight of the side of pork amounted to 16.68, 14.93 and 14.46 resp. Statistically significa nt differences were calculated for a majority of the above indicators between the evaluated groups of new-bred hybrids and the Slovhyb 1 cro ss (Large White x White Pork x Synthetic Line - BU x BM x SL). Product ion indicators showed daily weight gains ranging from 697 to 752 g and feed conversion per 1 kg weight gain 3.28 to 3.39 kg. As for meat qua lity, the percentage of PSE meat was not higher than 10% in the new-br ed hybrid cross. The results have documented that the test groups of h ybrids coming after selected parents showed higher growth ability, bet ter feed conversion and better carcass composition under the same cond itions of the external environment. A comparison of these results with the results achieved in the neighboring countries (Hungary, Czech Rep ublic, Poland, Austria) has indicated that the new-bred hybrid cross m ostly has the better carcass characteristics. The attained meatiness o f the dressed carcass is at the level of the results in the countries with advanced pig breeding and is compatible with carcass grading acco rding to the EUROP system.