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The work discusses the influence of the backfat thickness change, during sow´s lactation, on their subsequent litter characteristics. The reproduction potential of 478 sows of two genotypes was assessed. The genotypes were 50 Large White (LWD) sows and 428 crossbreeds Large White x Landrace (LWD x L) sows. The backfat thickness decline was examined in accordance to P2, backfat thickness in sows during lactation namely 1 day before planned parturition as well as weaning. From the obtained results it can be stated that the backfat thickness decline level during lactation has a small influence on the number of total born piglets. In contrast, the number of piglets born alive increased when backfat thickness rate increased. With a moderate backfat thickness decline, the average birthweight piglets gradually increased. However, the opposite trend was shown for the average weight at weaning. The backfat thickness decline level during sow´s lactation influences their farrowing interval. Animals with a lower increase of the backfat thickness subsequently showed a shorter farrowing interval (148.99, respectively 151.86 days), as well as a shorter weaning – estrus interval.

The aim of the study was to evaluate the effect of selected factors affecting fatty acids (FA) composition in pig fat. In the experiment, the influence of nutrition, gender, carcass weight, lean meat proportion (LMP) and intramuscular fat (IMF) were monitored. The effect of diet, specifically the influence of added linseed or corn on the fatty acids composition in the backfat was studied in pigs. From the perspective of the required increase of polyunsaturated fatty acids (PUFA) only the addition of the linseed proved to have a significant effect. Another evaluated aspect concerning the FA spectrum was the gender. While the backfat in barrows showed higher (P≤0.05) amount of monounsaturated fatty acids (MUFA), the backfat in gilts displayed a significantly higher proportion (P≤0.01) of the PUFA and total unsaturated fatty acids (UFA). A significant effect on the PUFA proportion has also been demonstrated for the lean meat proportion (LMP) parameter, which therefore represents not only a qualitative carcass meat parameter but also plays an important role in relation to the FA composition in the fat in pigs. In connection to the FA proportion changes the study also monitored the fat oxidative stability with the use of the TBARS method. Concerning the oxidative stability the effects of nutrition, FA groups, gender, carcass weight and LMP were studied. The relationship between the above mentioned factors and oxidative stability was found to be insignificant.

The aim of this study was to evaluate the influence of controlled nutrition on the selected muscle fibres indicators and carcass value in pork. The test included 72 hybrid pigs of the D x (LWD x L) genotype of a balanced sex (barrows/gilts). Animals were divided into two groups; the 1st (control) group was fed ad libitum, while the nutrition of the 2nd (experimental) group was restricted upon reaching 80 kg of live weight. The nutritional restriction was achieved by feeding the animals with maximum dose of CFM up to 2.8 kg*day-1 (corresponding to 36.4 MJ ME*day-1, 46.76 g NS*day-1 and 23.52 g LYS*day-1). From the obtained results it is evident that the daily feed intake restriction corresponds with greater number of the MLLT muscle fibers as well as with a higher IIB type muscle fibers share, higher lean meat share and a higher shoulder proportion in the carcass.