As the only sturgeon living in freshwater, sterlet is important for breeding in industrial fish farms, where lately cases of early mortality of this species have been detected. Hence, in order to preserve the species, it is important to study the parameters of fatty acid (FA) composition of lipid fractions of the blood serum of sterlet. Here we present changes of fatty acid composition in different lipid fractions of the blood serum of sterlets of different age (namely two-, three- and nine-year-old) with the masses 0.3–0.4, 0.5–0.6 and 5–6 kgfor the age-groups of fish, respectively. Fatty acid (FA) composition was determined using gas-chromatography on HRGC 5300 (Italy) in Palladin Institute of Biochemistry of the National Academy of Sciences of Ukraine (NASU). Fatty acid composition of starlet blood serum is presented by saturated and unsaturated high-molecular weight carboxylic acids, mostly palmic, stearic, oleic and linoleic. In the phospholipids fraction, there was a moderate increase in saturated and monounsaturated fatty acids and a slight decrease in polyunsaturated fatty acids depending on the age of fish. As for free fatty acids, there was a drop in the saturated ones depending on the starlet age. Among the free fatty acids of sterlet blood serum, we identified 28 acids, of them 39 %, 35 % and 30 % were saturated in 2-, 3-year-old and mature fish, respectively. Monounsaturated FA content was 14 %, 23 % and 23 % in 2-, 3-year-old and adult sterlet fish, and polyunsaturated FA content –46 %, 41 % and 36 %, respectively. The data can be used for the theoretical verification of correcting supplementary feed and premixes.

In two groups of rabbits of 24 animals each the dependence of NH4+-utilisation on the level of carbonic acid in the organism was investigates. The rabbits of the second group received injections into the abdominal cavity of 8 ml/kg body weight of a 5% NaHCO3-solution (enriched with CO2, pH 7.35) for the purpose of increasing the concentration of carbonic acid in the blood (pCO2: HCO3) and for the purpose of decreasing it an amount of NaCl-solution, which, in its content of Na+, was equivalent to the NaHCO3-dose. The difference in the concentration of carbonic acid in the blood between the two groups under the conditions of the experiment was between 30 and 35%, the pH-value was approximately the same. In order to investigate the NH4+-metabolism the animals of both groups received injections of 2 ml/kg body weight of a 1% (NH4)2HPO4-solution, their protein metabolism was studied after the intravenous injection of 2-14C-glycine. Together with the increase or decrease resp. of the level of carbonic acid in the organism, the keto acid concentration increases or decreases simultaneously. Due to the NH4-load the keto acid concentration in all animals decreases. it remains, however, higher in the animals with a higher HCO-3-level than in the control animals. The alpha-ketoglutarate concentration in the liver tissue of the animals with a higher HCO-3-level is, despite the NH4+-load, 87%, p less than 0.05, higher than in the control animals. The intensity of a removal of an NH4+-excess from the animal organism is directly dependent on the concentration of carbonic acid in the tissues. One hour after the NH4+-load the NH4+-concentration in the blood of the rabbits with a higher level of carbonic acid is normal again, whereas it is still 36% (p less than 0.05) higher than the original value in the control animals. In the liver and kidney tissues of the animals with an increased HCO-3-concentration 30 minutes after the (NH4)2HPO4-injection is by 16 and 14.5% (p greater than 0,05) resp. lower than that of the control animals. This is caused by the increased supply with NH4+-fixing substrates which are either formed directly or through intermediate stages by CO2-fixing reactions: oxaloacetate (the pyruvate concentration in the liver and kidney tissues compared to the control group was by 58%, p less than 0.05 lower), alpha-ketoglutarate, aspartate.(ABSTRACT TRUNCATED AT 400 WORDS)

Ключові слова: ЛІПІДИ, ЛІПОПРОТЕЇНИ, ГІПОБІОЗ, ГІПЕРКАПНІЯ, ГІПОКСІЯ, СИРОВАТКА КРОВІ, ЩУРИ INDICIES OF FATTY ACIDS SPECTRUM OF LIPIDS IN THE BLOOD SERUM OF RATS UNDER CONDITIONS OF ARTIFICIAL HYPOBIOSIS