Volume 22(2), 2023

Original Research Articles

Effect of the genotype and ageing time on physicochemical parameters of skeletal muscles in young bulls fattened in a semi intensive system

Piotr Stanek, Piotr Domaradzki, Paweł Żółkiewski, Mariusz Florek, Ewa Januś, Marek Kowalczyk

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Abstract. the aim of the study was to determine the effect of the genotype and ageing time on pH, water holding capacity, shear force and energy, and the myofibrillar index of m. longissimus lumborum and m. semitendinosus muscles in semi-intensively fed bulls. Carcass value indices and the chemical composition of the muscles depending on the genetic group were assessed as well. The study involved 46 young bulls from four genetic groups, i.e. the Hereford breed (HER - 8 bulls), the Limousin breed (LIM - 8 bulls), commercial cross-breeds (MT - 14 bulls), and the Polish Black-and-White Holstein-Friesian breed (PHF - 16 bulls). The analyses showed that the semi-intensive fattening system ensures production of carcasses with satisfactory slaughter yield and quality parameters (good musculature and moderate fatness). The best quality parameters were determined in the meat from the LIM and MT young bulls, whereas the poorest results were exhibited by the PHF beef. The ageing time had a positive effect on the meat quality parameters (especially tenderness and color), contributing to a significant reduction in the differences between the genotypes observed in the initial postmortem period. The results of the shear force and myofibrillar index, i.e. parameters of meat tenderness, suggest that a 14-day ageing period seems to be the necessary minimum. This period should even be extended in the case of the LL muscle of HER and PHF young bulls or the ST muscle of HER, MT, and PHF young bulls. Further research with consumer assessment is therefore advisable to determine the optimal ageing time of beef produced in the country.

The effect of different content of protein and urea in milk, as biomarkers of energy-protein balance of food rations, on the level of selected milk performance characteristics of Polish Holstein-Friesian cows

Piotr Guliński

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Abstract. The aim of the study was to assess the impact of varied levels of milk protein and urea content on selected milk production traits of Polish Holstein-Friesian cows. The research included 34,397 data sets related to daily milk production of Polish Holstein-Friesian cows. These animals were kept in 15 cattle herds located in the Mazovian and Podlasie voivodeships. In the first stage of the research, the animals were differentiated based on the level of urea in their milk and the percentage of protein. According to the adopted assumptions, the energy and protein balance level of feed rations was determined based on the concentration of urea and protein in the milk. Due to the level of urea, three cow groups were distinguished: <150, 150–250, and >250 mg · L-1. Depending on the concentration of protein in the milk, the following three groups of animals were determined: <3.2%, 3.2–3.6%, and >3.6%. The assessment of the impact of varied energy and protein balance levels in feed rations on selected milk production traits of cows was conducted in subsequent lactation periods, production level and fat to protein (F/P) groups. Four lactation periods were distinguished, which covered successive months of lactation: 1–3, 4–6, 7–10, and 11–18, three production groups, determined based on the following levels of daily milk yield: <20, 20–30, and >30 kg and as well three groups of cows with different F/P ratio in milk were distinguished: <1.2, 1.2–1.6, >1.6. In the next stage of the study, a detailed assessment was conducted on the impact of varied levels of energy and protein balance in feed rations on the analyzed milk production traits. The analyzed population of cows was divided into 9 groups based on the level of urea content (mg · L-1) and protein concentration (%), with varying levels of coverage of the protein and energy requirements of cows. The interdependencies between milk performance traits of cows fed diets with balanced levels of energy and protein and their peers, for whom the nutritional diets were differentiated based on energy-protein balance, were determined using Pearson correlation coefficients and linear regression. When assessing the energy supply of cows, the study showed that too low energy levels in diets lead to a decrease in the chemical composition of milk, while too high levels lead to a decrease in milk yield compared to peers fed optimally balanced diets. Milk from cows with inadequate energy and protein nutrition contained less fat and protein by 0.54% and 0.59%, respectively, compared to milk from cows fed optimally. On the other hand, excessive energy supply was accompanied by an increase in fat (+0.66%) and protein (+0.57%) concentration with a decrease in daily milk yield (-4,1 kg). When evaluating the level of protein coverage for cows, the study showed that an excess of protein in feed led to an increase in urea levels in milk. The level of urea in milk from cows fed with excess protein in their feed (>250 mg · L-1 and <3.2%; >250 mg · L-1 and >3.6%; >250 mg · L-1 and 3.2–3.6%) contained more urea per liter compared to milk from cows fed a balanced diet, with increases of 127, 107, and 109 mg, respectively.

Effectiveness of blood electrolyte homeostasis regulation in polar foxes (Alopex lagopus, Linnaeus 1758)

Wiesław Skrzypczak, Roman Szymeczko, Katarzyna Wiśniewska-Kwaśnik, Anna Piątek

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Abstract. The Arctic fox (Alopex lagopus, L. 1758) is maintained in captivity for breeding purposes due to the high quality of its winter fur. The success of breeding these animals depends primarily on their health, which determines high reproductive rates, low neonatal mortality and proper development of young animals. A prerequisite for maintaining good health is the maintenance of a constant internal environment, especially water-electrolyte and acid-base homeostasis. Sodium, potassium and chloride are the main electrolytes affecting volemia and osmolality of body fluids. In the current study, the results regarding the renal capacity of six-month-old foxes to regulate sodium, potassium, and chloride levels are presented, considering the sex of these animals. It has been shown that the concentration of sodium, potassium, and chloride in the blood serum of six-month-old polar foxes, as well as the osmotic pressure of the blood serum, were within the upper limits of physiological normal range. Higher concentrations of sodium and potassium were observed in males of these animals. Nonetheless, the results indicated efficient regulation of blood electrolyte homeostasis, both in females and males.

Characteristics of selected parameters of antlers of the farmed fallow deer (Dama dama) in Poland

Aleksandra Barańska, Krzysztof Głowacz, Marek Bogdaszewski, Żaneta Steiner-Bogdaszewska, Marcin Świątek

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Abstract. The aim of the study was to estimate antler parameters (mass, volume, density) of fallow deer (Dama dama) kept in in the Research Station of the Institute of Parasitology, Polish Academy of Sciences, Kosewo Górne. The study involved 25 stags divided into 4 age groups: 2 years old (n=4); 3 years old (n=4); 4 years old (n=12); 5 years old (n=5). Antlers were cut before rutting when animals already rubbed velvet off. The analyses showed the significant differences in the mass and volume between age groups. Mass and volume increase with age while density was levelled.

Analysis of variability in reproductive traits and breeding efficiency in rabbits (Oryctolagus cuniculus L. 1758) of the Popielno White and Termond White breeds

Stanisław Socha, Dorota Elżbieta Weremczuk, Dorota Kołodziejczyk

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Abstract. In the study, the variability of reproductive traits (the number of born and weaned young) and the efficiency of breeding work were assessed and estimated in rabbits (Oryctolagus cuniculus L. 1758) of the Popielno White and Termond White breeds. Phenotypic trends of reproductive traits were estimated over a period of ten years in farms included in the analysis. The research material included data on the performance of 1836 female rabbits of the Termond White breed and 1237 female rabbits of the Popielno White breed, maintained on reproductive farms over a period of ten years. Analysis of variance for reproductive traits showed that sources of variability (farm, calendar year, and breed) had a statistically significant impact on the number of born and weaned rabbits. The average litter size obtained from female Termond White rabbits ranged from 2.89 to 3.54 within one year. For female Popielno White rabbits, this average was 3.44. The average number of born and weaned kits per litter during the analyzed period was 8.99 and 8.29, respectively. The reproductive results obtained regarding the number of born and weaned rabbits can be considered very good. The phenotypic trend line for the number of born and raised rabbits of the white Popielno breed showed an increasing tendency, while in the case of rabbits of the white Termond breed, it exhibited a decreasing trend. Clear fluctuations in the number of born and raised rabbit kits in the Termond white breed throughout the research period indicate the need to improve the reproductive traits of this breed through intensified selection. In the light of our own research, it can be stated that rabbit breeding in both farms is conducted properly, and the obtained results are satisfactory.
This Volume

Acta Sci. Pol. Zootechnica 22(2) 2023