The increase in demand for food products among the population determines the rapid intensification of various branches of agriculture, in particular rabbit breeding. Increase of production capacity is achieved at the expense of full use of productive qualities of animals, however, the course of physiological processes in the body can change.

In the conditions of oxidative stress and uncontrolled generation of active forms of oxygen, processes of uncontrolled modification of proteins become dominant, which leads to loss of their biological activity (enzymatic, receptor and transport functions). The oxidative modification of proteins generates new antigens and provokes an immune response. Products of such modifications can cause secondary damage to other molecules. Therefore, when changes in production conditions that are accompanied by the development of oxidative stress, the processes of oxidative modification of lipids and proteins should be under constant laboratory monitoring. The purpose of the work was to study the features of oxidative modification of lipids and proteins in the organs of rabbits of New Zealand breed of all ages.

The research was conducted on rabbits of the New Zealand breed at Gregut Ltd vil. Kozhanka, Fastov District, Kyiv Region. On the principle of analogues (age and weight), two groups of animals were formed – control and experimental (100 heads in each). The animals are fed with standard feed, balanced with all nutrition parameters, with free access to feed and water. The whole period of research was 90 days.

Materials for research were the heart, the brain and the longest muscle in the back, which were selected after slaughter in animals of 1-, 15-, 30-, 45-, 60-, 75- and 90-days of age. The state of the processes of peroxide oxidation of lipids and proteins was determined by generally accepted methods for the content of hydroperoxide lipids (HPL), products that react with thiobarbituric acid (TBA-AP), ketodinitrophenylhydrazones (KDNFG) and alphadinitrophenylhydrazones (ADNFG) of neutral and basic character. LPO plays an important role in the regulation of oxidative phosphorylation and permeability of cell membranes. Excessive formation of active forms of oxygen can cause damage and death of cells. The obtained data testify that processes of lipoperoxidation in the body of rabbits proceed with varying intensity and do not have a clearly expressed tissue specificity.

Proteins take an active part in all vital processes. Therefore, the study of the dynamics of their content in animal tissues is one of the important indicators of the physiological state of their organism. Proteins are essential for the growth and development of animals, the synthesis of enzymes and hormones. An early indicator of cell damage under free radical oxidation is the oxidation of proteins (OMB). It is believed that OMB plays a key role in the molecular mechanisms of oxidative stress and is a trigger for oxidative degradation of other molecules, in particular, lipids and nucleic acids. Destruction of proteins is a more reliable marker of oxidative tissue damage than peroxide lipid oxidation, since OMB products are more stable than peroxides of lipids, which are rapidly metabolized by peroxidases and low molecular weight antioxidants.

The main amount of dinitrophenylhydrazones (DNFH) belongs to the KDNFG and the ADNFH of a neutral nature. In the body of rabbits, it was found that the content of KDNFH was neutral and of the highest nature in brain tissues, but there was a tendency to decrease these parameters with age. Instead, the number of these products was probably the smallest in the heart and the longest muscle in the back.

The content of KDNFN neutral in the heart of rabbits at the end of the experiment decreased by 39 %, and the longest muscle back by 28 % compared with the start of the experiment. The analysis of the main and neutral ADNFHs also showed a lower content of these products in the heart and the longest muscle in the back. Thus, on the 90th day of the experiment in the heart of rabbits, the content of the ADNFH of a neutral character decreased by 36,4 %, while in the longest muscle the back was 41,5 % compared to the beginning.

Complex studies of various indicators of free radical oxidation of lipids and proteins in New Zealand rabbit organs have allowed a more complete description of the course of peroxidation processes in the organism of the animals under study. In the heart of rabbits, a strong negative (r = -0,9) correlation between the content of TBA-AP and DNFH of neutral and main origin was detected. A moderate negative (r = -0,6) relationship between the content of the HPL and the OMB products of neutral and basic nature was also noted in the brain. However, the content of TBA-AP and OMB products in this organ have a moderate degree of linear correlation (r = + 0,55). The content of LPA products in the rabbit brain has a strong positive correlation (r = + 0,9).

Key words: oxidative modification of proteins, peroxide oxidation of lipids, rabbits, heart, brain, tne longuest muscle of the back.