of the meat tenderness using canonical correlation analysis. Based on the percentage participation of the selected muscle tissue and centrifugal drip proteins and measurements of pH and EC at specified time pm it was possible to predict tenderness with a very high probability, even 89%.

The aim of the study was to determine the possibility of inclusion of cold‐pressed rapeseed cake (CPRC) in diets for common carp, Cyprinus carpio L. Four isonitrogenous (322 g kg−1 crude protein) and isoenergetic diets (17.5 MJ kg−1) with four levels of CPRC incorporation 0, 110, 220 and 330 g kg−1 (treatments RC0, RC11, RC22 and RC33, respectively) were evaluated in a 50‐day growth test with common carp of 500 g initial weight. Statistically significant higher final weights (1215–1243 g) were obtained in fish fed diets including CPRC. Fish growth rates were nearly identical in all treatments (specific growth rate of 1.7–1.8% day−1). Similar results were obtained in respect of feeding coefficients (FCR) that ranged from 1.6 to 1.8. Crude protein and ash concentration in fish bodies did not change. Statistically significant decreases in moisture content were found in carp in groups RC22 and RC33. Statistically significant increase of crude lipid in fish bodies were found in groups RC22 and RC33. The slaughter traits and meat quality analysis of carp did not show significant differences. We conclude that it is possible to include up to 330 g kg−1 of CPRC in diets of 2‐year‐old common carp without significant effects on growth and food utilization.

Abstract. The aim of the investigations was to analyse the share of myosin heavy chains (MHC) isoforms (type I, IIa, IIb, and IIx) in the longissimus thoracis et lumborum muscle derived from pigs of different RYR1 genotypes (TT – homozygous negative, CT – heterozygous, CC – homozygous positive). The composition of the MHC isoforms in the muscle tissue of the examined animals was referred to selected meat quality traits. It was revealed that the animals with the CT and TT genotypes were characterized by a significantly (P≤0.05) lower share of the type I and higher share of the type IIb MHC isoform in comparison to homozygotes CC. Inferior tenderness and water holding capacity of meat obtained from pigs susceptible to stress (TT) at 144 h after slaughter could have been associated, among others things, with the increased share of MHC isoform type IIb. The composition of MHC isoforms might be a useful indicator in breeding work in the selection of animals carrying the gene of susceptibility to stress.

In the first of two experiments, four rumen cannulated wethers were used to determine the extent of rumen protein degradation in soyabean meal (SBM), rapeseed meal (RSM) and extruded field bean seeds (EFB), using the in sacco method. Rumen non-degradable N in SBM, RSM and EFB of total-N was 38, 29 and 48%, respectively. In the second experiment, four rams with cannulas in the duodenum were fed isoenergetic total mixed rations (TMR) containing similar amounts of protein truly digestible in the small intestine (PDI). TMR consisted of meadow hay and concentrate (50:50, DM basis) in which SBM, SBM+RSM and SBM+EFB were the main sources of protein.The highest, statistically significant (P<0.05) methionine and cystine concentrations in the duodenal digesta were found in sheep fed SBM+RSM diet, while the lowest -in those fed SBM+EFB diet. Significantly higher (PO.05) flows of total N (33.49 g/day), non-ammonia N (33.08 g/day) and total amino acid (197.7 g/d) were observed in sheep fed rations with SBM + EFB.

The first aim of the study was to compare selected meat quality parameters in porkers without the gene RYR1T (ryanodine receptor gene). These were porkers slaughtered at 100 to 115 kg and 116 to 130 kg live weight. The second aim of the study was to determine the occurrence frequency of standard-quality meat (red, firm, nonexudative [RFN]) and the occurence frequency of defective meat (pale, soft, exudative [PSE] and acid, soft, exudative [ASE]). The analysis was conducted on the longissimus lumborum muscle in 114 crossbred porkers. The porkers were a cross of Camborough 22 sows and boars from lines 337PIC (Pig Improvement Company), Norsvin Landrace and Pietrain. All of the animals were provided with identical environmental and nutritional conditions. The average weight of the slaughtered animals in the light and heavy groups was 110 kg and 122 kg, respectively. Both groups had the same average post-slaughter meatiness (56.5%). A statistical analysis of selected meat-quality parameters did not show any significant differences between the weight groups. On the other hand, the classification based on carcass quality showed an occurence frequency of defective meat in heavier crossbred porkers (116 to 130 kg) that was three times higher than in those crossbred animals which weighed 100 to 115 kg when slaughtered. In porkers without the gene RYR1T, the defective meat types PSE and ASE occurred with a frequency of 17.54%.