The objective of this study was to determine the effect of genotype and carcass conformation class on the slaughter quality of 200 young bulls, including 108 crossbred beef bulls and 92 Holstein- Friesians (HF), aged 21-22 months, selected in the lairage. The lean meat content was estimated and body measurements were taken before slaughter. After slaughter, the carcasses were graded according to the EUROP system, and carcass quality parameters were determined. Intramuscular fat was extracted from samples of m. longissimus dorsi, and the fatty acid profile of extracted fat was determined by gas chromatography. 61.11% carcasses of crossbred beef bulls were graded in the conformation class R, and 56.53% carcasses of Holstein-Friesians were classified as O. The majority of carcasses belonged to fat class 2, which was not consistent with intramuscular fat content. Within the same conformation classes, crossbred beef bulls were characterized by higher slaughter quality than Holstein-Friesian bulls. Meat from hybrid beef bulls had a higher (by 0.42% on average) content of fat with a more desirable composition. Since the population size of beef cattle will probably not increase in the nearest future, efforts should be continued to optimize the production of high-quality beef from dairy cattle herds.
An evaluation was conducted of the suitability for fattening in a semi-intensive system (mainly with fodders from permanent grassland) and the slaughter value of 15 young bulls of the Polish Red (PR) breed and 10 each of the White-Backed (WB) and Polish Black-and-White (BW) breeds. The reference group consisted of young bulls of the Black-and-White variety of the Polish Holstein- Friesian (HF) breed and the Simmental (SIM) breed, fattened on the same farms. Control fattening was carried out until the age of 18 months. Mean daily weight gain in the bulls of the native breeds during the control fattening period (which lasted 314-358 days) was 0.9 kg, similarly to HF, but significantly lower (P≤0.05) than in the Simmentals (986 g). During the entire fattening period, i.e. from birth to the age of 18 months, daily weight gain was 832 g in PR and 889-919 g in WB and BW. Dressing percentage was lowest in PR bulls (51.69%), and higher in WB (53.1%) and BW (53.49%), with values similar to the reference group, i.e. young bulls of the Simmental (52.97%) and HF (53.29%) breeds. The difference between PR and BW (1.8%) and HF (1.6%) was statistically significant (P≤0.05). In the EUROP classification system, the carcasses of the young bulls of the native breeds were most often placed in classes R- and O+ (conformation) and 2+ and 3- (fat cover), as in the case of young HF bulls. Carcasses of young Simmental bulls were assigned to much higher classes. The young bulls of the three Polish native breeds evaluated are good material for fattening in a semi-intensive system (mainly with fodder from permanent grasslands), while the young PR bulls were the least suitable