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Production of high-quality food of animal origin directly depends on the health of farm animals. Feeding of farm animals balanced in terms of nutrients is the most important condition for improving the quality of livestock production and its productivity. The productivity of animals depends on providing their organisms with all the necessary nutrients and biologically active substances. Along with the nutritional value, chemical safety of feed is also important for animals and humans. Pesticides have a special place among chemical toxicants. The article presents the monitoring of the nutritional value and chemical safety of the main feeds of agricultural producers of the Republic of Tatarstan, based on the results of their physical and chemical studies carried out in 2019 by of "FCTRBS". The feed was tested for content of crude protein, moisture, crude fat, crude fiber, ash, and pesticides in accordance with the test methods included in the scope of accreditation of Test Center. 94.4% of feed for farm animals in the Republic of Tatarstan meet the requirements for nutritional value and chemical safety, which are imposed on them by the current regulatory and technical documentation. Only 5.6% of the studied feeds did not meet the physical and chemical parameters (the content of crude protein, crude fat, moisture, ash). A comprehensive assessment of the results of physical and chemical studies shows that agricultural feed producers in the Republic of Tatarstan comply with the basic requirements of the normative and technical documentation for the nutritional value and chemical safety of feed for farm animals. The latter determines not only the quality of animal husbandry, but also its efficiency and productivity.

The article presents the results of the application of the oxidation reaction of N-methyl-p-aminophenol with hydrogen peroxide, catalyzed by Fe(II) and Fe(III) ions in the flow injection analysis (FIA) of tap water. Using a commercially available system for FIA with spectrophotometric detection, an optimal scheme for conducting an indicator catalytic reaction in a liquid stream was proposed, which was used to determine the total iron content in tap water. Spectrophotometric detection of colored products of the indicator catalytic reaction of the oxidation of N-methyl-p-aminophenol with hydrogen peroxide is carried out at the absorption maximum of the absorption spectrum in the visible region at λmax = 490 nm. It was shown that, under nonequilibrium FIA conditions, it is possible to significantly minimize the contribution of the noncatalytic reaction to the total analytical signal. The latter is accompanied by the expansion of the range of determined catalyst contents to lower concentrations. Taking into account the proposed FIA scheme for determining the total iron content in tap water by the oxidation of N-methyl-p-aminophenol with hydrogen peroxide, catalyzed by Fe(II) and Fe(III) ions, the linearity range of the analytical signal remains in the range of 0.05-0.4 μg/ml. The lower limit of the determined iron content is 0.02 μg/ml with a productivity of 40 samples per hour. Sample preparation of tap water consists in filtering and maintaining the required pH for the catalytic indicator reaction and subsequent FIA. The cations Al, Zn, Ni, V(V), Pb, Cd, Mn(II), and Cr(VI) do not have a significant interfering effect; only the presence of complexing agents can reduce the rate of the catalytic reaction, which, accordingly, affects the analysis results.

The article presents the survey data of 1830 average samples of feed, feed raw materials and food products received through the Test Center of the FSBSI «FCTRBS-RRVI»", provided by livestock and feed enterprises, agricultural companies, food manufacturers and 152 samples of feed provided by specialists of veterinary services , livestock enterprises, owners of peasant farms to determine the death of animals and birds, for the content of mycotoxin deoxynivalenol (DON) in the period from 2018 to 2020. Determination of the DON content in the samples was carried out according to a certified procedure based on the method of thin layer chromatography. In the course of summarizing the results, it was found that samples of feed, feed raw materials and food products received through the Test Center of the of the FSBSI «FCTRBS-RRVI» from different regions of the Russian Federation in terms of DON content corresponded to the normative indicators specified in the current regulatory and technical documentation. When determining the cause of death of animals and birds, 152 samples were examined, received from farms of different regions of the Republics of Tatarstan, Bashkortostan, Mordovia, Kostroma and Ryazan regions. It was found that 1.97% of samples were contaminated with DON at concentrations from 0.2 to 0.5 mg/kg of feed, in the rest, the content of mycotoxin was below the sensitivity of the method (< 0.2 mg/kg), which does not exceed the limit permissible concentration. It was recommended to exclude feed contaminated with mycotoxin from the diet of animals, since at the established concentrations, DON is not the main etiological factor in the death of animals, but due to the presence of carcinogenic, mutagenic, teratogenic, embryotoxic and immunosuppressive properties, together with other factors, it is contributing.

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