## 3 Results and Discussion
[PERSON] and [PERSON] [61] compared the quality of the meat of the native Pulawska breed with the hybrids of fattening pigs and found better biological properties of Pulawska meat than DanB and Naima hybrids, which is explained by the higher number of slow-twitch oxidative (Type I) and lower number of fast-twitch glycolytic (Type IIA) muscle fibres, which are found in the muscles of the Pulawska pig. The higher content of slow-twitch oxidative (Type I) fibres noted in the native breed is a characteristic feature of wild boar and primitive breeds [62; 32]. Table 4 shows the quality characters of raw loin (_m. longissimus thoraci_) of the different genotypes. We found differences for a* parameter and no differences for cooking loss (\(\%\)). These results are consistent with the data of [PERSON] et al. [37], who reported significantly lower drip loss and WHC values for the _m. longissimus thoracis_ of ZS pigs compared to Pulawska and Polish Landrace pigs. Additionally, earlier studies showed lower drip losses in Korean native black pigs [63] and higher pH\({}_{\text{u}}\) values in Iberian pigs [64] for _m. longissimus lumborum_ compared with commercial breeds. Variations in the fibre type composition may affect meat colour. The right colour of meat can be conditioned by the ferrous oxymioglobin (oxyMb) [65], which is directly connected with the percentage and the size of muscle fibre types [66]. [PERSON] et al. [24] suggested that haem pigments had a positive correlation with the percentage of type I muscle fibres and a negative correlation with that of type IIB fibres. The present research showed that the a* color parameter was positively correlated with the frequency of the muscle fibers IIA and the size of all types of muscle fibers (\(\mathcal{O}\)\(\upmu\)m). The above correlations were significant, as shown in Table 5. Colour parameters (L*, and a* values) of the _m. longissimus thoracis_ of ZS pigs and the hybrids of this breed correspond to the meat parameters of other native pig breeds as reported [64; 67]. According to [PERSON] and [PERSON] [49], the meat of Zlotnicka spotted pigs compared to the [PERSON] breed was darker, which was associated with a greater percentage of type I fibres and a smaller percentage of type IIB fibres. The colour of meat and the fat content may also be a significant determinant in the evaluation of pork quality [68]. Hybrid (ZS \(\times\) ZS) \(\times\) D pigs were characterised by a significantly higher intramuscular fat content (4.08\(\%\)) in the _longissimus thoracis_ muscle in comparison with ZS \(\times\) PLW hybrid pigs (2.95\(\%\)). [PERSON] and [PERSON] [69] proved that the intramuscular fat (IMF) between 2\(\%\) and 3\(\%\) is to be considered as an optimal level. The IMF is an important marker of meat quality because higher contents of intramuscular fat exert a positive influence on sensory characteristics and the technological and culinary usefulness of meat [5; 70; 71]. The IMF is of particular importance in the case of raw meat used for ripening products. It is an element enabling a normal course of ripening processes and a factor responsible for the favourable development of sensory characteristics of such products [72; 73]. It is generally accepted that local breeds produce a higher IMF content [1; 37; 63; 64; 74]. As [PERSON] et al. [75] indicate, muscles of the Spanish breed Iberico are characterised by a particularly high content of fat (8.8\(\%\)). Considerable IMF ranging from 3.32 to 4.27\(\%\) in the _m. longissimus dorsi_ was reported for the native Italian breed of Nero Siciliano [76]. On the other hand, [PERSON] et al. [77] determined the content of IMF in the Slovenian breed of Krskopolje at 3\(\%\). The results of research on the IMF in Polish native pigs vary. [PERSON] et al. [78] determined the content of IMF in ZS pigs at 1.02-2.07\(\%\). [PERSON] et al. [79] noted the mean content of IMF of 2.04\(\%\) in Zlotnicka Spotted pigs and 1.87\(\%\) in the Zlotnicka White breed. However,  
the IMF content in ZS pigs observed in the research by [PERSON] et al.