This study was conducted to evaluate animal performance, carcase characteristics and meat quality of young bulls and steers (Charolais  Holstein-Friesian), fattened until 15 and 18 months of age. One half of 40 young bulls were castrated at 2 or 3 weeks of age. Starting at 7 months of age, they received grass silage supplemented with concentrates. At the end of the fattening period, the animals were slaughtered, and carcase quality and the quality of meat from Musculus longissimus thoracis (MLT) were evaluated. Bulls had a higher carcase dressing percentage, and their carcases had higher lean meat content than steers. MLT from steers had higher intramuscular fat (IMF) content (by 0.89%); it was less tough, more tender and palatable. IMF from bulls had higher concentrations of polyunsaturated fatty acids (PUFAs) and a higher n-6/n-3 PUFA ratio than IMF extracted from steer meat. Older animals had higher carcase quality than those slaughtered at 15 months of age, and slaughtering at a later age had no negative influence on meat quality. ARTICLE HISTORY

A four-year field experiment was conducted in north-eastern Poland. The aim of the study was to determine the direct and residual effects of increasing doses of meat and bone meal (MBM) on the available phosphorus content of soil and the total phosphorus content in crops above ground biomass or grain. Experimental factor I was MBM dose (1.0, 1.5, 2.0 and 2.5 t/ha/year, and 2.0, 3.0, 4.0 and 5.0 t/ha/every second year), and experimental factor II was the year of the study (four consecutive years). The application of increasing MBM doses to slightly acidic soil insignificantly decreased its pH, but it did not change soil classification. The use of MBM as a fertilizer increased the levels of available phosphorus, compared to the treatments with mineral fertilization. The grain of winter triticale and winter wheat and the green matter of maize contained higher concentrations of phosphorus after the MBM application, in comparison to the plants receiving mineral fertilization. Phosphorus uptake by winter wheat and maize plants (dry matter basis) was higher in treatments with MBM (in particular applied every second year) than in treatments with NPK fertilization. Irrespective of the frequency of MBM application, phosphorus uptake by winter rapeseed was considerably lower, compared to the control plants.

The aim of this study was to determine the effect of meat and bone meal (MBM) used as an organic fertilizer on maize grown for grain. A two-factorial field experiment in a randomized block design was carried out in 2010 and 2011, in north-eastern Poland. Experimental factor I was MBM dose (1.0, 1.5, 2.0 and 2.5 t ha -1 year -1), and experimental factor II was the year of the study (two consecutive years). Increasing MBM doses contributed to an increase in maize grain yield and 1000-grain weight. The yield-forming effect of MBM applied at 1.5 t ha -1 year -1 was comparable with that of nitrogen and phosphorus contained in mineral fertilizers. A dose of 2.5 t ha -1 MBM led to a significant increase in maize grain yield. The P and K content of maize grain was determined by MBM dose, whereas the concentrations of N, Mg and Ca in grain were not affected by MBM dose. Significantly higher N, P, K and Mg uptake by maize plants was observed in treatments with the highest MBM dose, compared with the control treatment. Nitrogen and phosphorus uptake per 1 t MBM reached 101 kg and 26 kg, respectively. The results of a twoyear study show that the maximum MBM dose (2.5 t ha -1 year -1) met the fertilizer requirements of maize with respect to nitrogen and phosphorus.

The objective of this study was to determine the effect of body weight (BW) at slaughter and fattening intensity on carcass fatness and meat fatty acid profile in young Holstein-Friesian bulls. One-hundred bulls fattened on two levels of intensity a semi-intensive (SI) and an intensive (I) were used. Fattening was carried out to BW of 500, 550, 600, 650 and 700 kg. Live ultrasound measurements were performed to determine back fat thickness. Carcass dressing percentage, carcass conformation and fatness, intramuscular fat content of m. longissimus dorsi and fatty acid profile (by gas chromatography) were determined after slaughter. Intensively fattened bulls were characterised by a greater carcass dressing percentage -by 1.17% on average, greater carcass conformation scores, greater external fat thickness and a greater intramuscular fat content than bulls SI fattened. Fat from intensively fattened bulls contained higher levels of polyunsaturated fatty acids (PUFAs) -by 0.96/100 g on average. Semi-intensive fattening contributed to a decrease in the n-6/n-3 PUFA ratio and to a significant increase in the concentrations of C18:2 and C20:4 fatty acids. Regardless of the fattening intensity, the n-6/n-3 ratio was greater in heavier animals. The best results were achieved when young Holstein-Friesian bulls were fattened intensively to BW of 650 kg.