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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.

Cervidae are characterised by specific requirements for nutrients due to the structure of their gastrointestinal tract. The period of development of male antlers and lactation in females is associated with increased demand for protein, energy, and minerals. The paper presents the importance of Ca and P in cervid nutrition and the effect of these minerals on the health and ontogenic quality of these animals. The requirements for these macronutrients in relation to the age and sex of cervids as well as food availability are presented in the study. Periods in animals' life that require particular attention especially in farm breeding and methods for balancing dietary doses are indicated. Additionally, the relationships governing the availability of Ca and P in the environment and the effects of deficiency and excess of these minerals in the deer diet are discussed.

SummaryRecent years have seen increasing interest in the conservation and use of native breeds of livestock raised in traditional farming systems. The experience of many European countries shows that promotion of raw materials and products derived from these breeds through a labelling system has a beneficial effect on the sustainable development of rural areas, contributes to preservation of the cultural heritage of the countryside, and increases the population of the breeds. As yet no beef produced in Poland has been included on the European list of traditional and regional products. 5 N and 59.1 N). On the last, 14 th day of ageing, the instrumental WBSF shear force for the breeds evaluated was definitely more homogeneous and did not differ significantly (shear force in the range of 56.3-65.7 N; P > 0.05). Compared to the muscle of native breeds, that of the Polish Holstein-Friesians showed significantly lower haem pigments (on average 35 ppm less; P < 0.01) and a lower proportion of redness (a*) (P < 0.01) on the 2 nd and 7 th days post mortem. The MLL muscle of young bulls of the Polish Red breed had the lowest (P < 0.01) percentage content of yellowness (b*) during the whole ageing period. Significantly (P < 0.01) lower oxidative stability (higher TBARS value) was found in the meat from young bulls of the Polish Holstein-Friesian breed (on the 2 nd and 7 th days post mortem) and the White-Backed breed (on the 14 th day) compared to all other breeds analysed. In general, the ageing time had a positive influence on the muscle quality, as the determinants of the visual and sensory attractiveness of the meat, which are also important in the meat industry, remained stable (pH), improved (colour and water-holding capacity G-H) or became more similar among the breeds (tenderness assessed on the basis of shear force, cooking loss).

the material for the study consisted of 80 samples taken from the longissimus lumborum (ll) and semitendinosus (ST) muscles of young bulls of five breeds (8 samples of each muscle per breed), including three native breeds included in the genetic resources conservation programme, i.e. Polish red, White-backed and Polish black-and-White, which together with the simmental and Polish Holstein-Friesian breeds. The content of the elements (K, Na, Mg, Ca, Zn, Fe, Mn, and Cu) analysed in the meat of the young bulls (fattened in a semi-intensive system on fodder from permanent grassland) was found to depend (in varying degrees) on the breed of cattle. The greatest differences (P<0.01 and P<0.05) were noted between the Polish Holstein-Friesians (PHF) and the remaining breeds, mainly in the content of Mg, Ca, Zn and Mn. The results obtained in the four other breeds for most of the macro-and microelements were more uniform, with the highest content noted in the muscles of the young bulls of the native breeds.

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The aim of the study was to compare the skeletal muscles (longissimus lumborum – LL vs. semitendinosus – ST) of Polish Holstein-Friesian bulls in terms of their chemical composition, fatty acid proportions and the degree to which they meet standards for selected nutrients. The proximate composition, that is, the content of water, ash, crude protein, fat and collagen, was determined in the muscle samples collected. The calorific value of 100 g of meat was calculated based on the total protein content and intramuscular fat, using energy equivalents: 4 kcal for protein and 9 kcal for fat. The fatty acid profile (FA) was determined by gas chromatography (GC-FID), and the following groups were distinguished: saturated fatty acids (SFA), monounsaturated fatty acids in the cis (MUFA cis) and the trans configuration (MUFA trans), as well as polyunsaturated fatty acids (PUFA). On the basis of the content of individual fatty acids, the ratio of PUFA/SFA and n-6/n-3 was calculated. In addition, the following indices were calculated: atherogenic index (AI), thrombogenic index (TI), saturation index (S/P), as well as nutritional value (NV) and the ratio of hypo- and hypercholesterolaemic fatty acids (h/H). The results obtained for fatty acids were expressed as 1) percentage of individual fatty acids in total FAs quantified and 2) as quantity (in mg) per 100 g of fresh meat. Statistical calculations were performed using Statistica software ver. 13. Differences between the muscles were verified with the t-test for independent samples, assuming significance levels of p ≤ 0.05 and p ≤ 0.01. The muscle type was found to significantly influence the fatty acid (FA) profile for four of the 24 FAs identified. Compared to ST, the LL muscle had a significantly higher share of C18:0 (18.95% vs. 16.55%; p ≤ 0.01) and CLA (0.38% vs. 0.29%; p ≤ 0.05) and significantly lower percentages of C16:1 c9 (3.17% vs. 3.74%; p ≤ 0.05) and C18:1 c9 (36.02% vs. 38.65%; p ≤ 0.05). With regard to particular groups of fatty acids, the LL muscle had significantly higher percentages of SFA (53.20% vs. 50.71%, p ≤ 0.05), PUFA (4.20% vs. 3.49%, p ≤ 0.05) and n-6 (2.69% vs. 2.10%, p ≤ 0.01) and a significantly lower percentage of cis MUFA (40.73% vs. 43.96%; p ≤ 0.01). The average amount of fat in 100 g of muscle tissue was 693.30 mg for SFA, 560.81 mg for MUFA cis, 54.74 mg for PUFA (including 33.87 mg of n-6 and 16.23 mg of n-3) and 24.63 mg for MUFA trans. The beef can be classified as a secondary source of fatty acids. The coverage of the recommended intake ranged from 2.5% to 3.8% for SFA, from 1.1% to 1.9% for MUFA, from 0.29% to 1.8% for n-3 acids, and was smaller than 1% for PUFA and n-6. The amount of EPA and DHA satisfied from 0.66% to 1.3% of the minimum daily requirement, while the amount of trans FA ranged from 0.9% to 1.4% of the maximum daily level. It is worth noting that 100 g of the beef provided on average 102.53 kcal, 1.46 g of fat and 22.34 g of protein, which cover, respectively, 5.1% of the daily calorie requirement, 1.9-3.3% of the fat requirement, and as much as 30-45% of the protein requirement for adults. Although the ST muscle, because of its 40% lower fat content and 2% lower protein content, was less caloric than the LL muscle, it also contained fewer biologically active FAs, including CLA, VA, ALA, LA, AA, EPA and DPA. Irrespective of the differences shown, the meat can be classified as a low-calorie and high-protein product, as 87% of its energy value came from protein.