Human and animal strategy of behavior is based on two reactions: active (aggression and run away) and passive (stand still), which was first described by Cannon in research conducted on cats. But none of these forms of reactions to stress factor is identical to the animal state before slaughter, when the animal feels not only danger but also is in a stalemate (impasse). In our opinion this situation leads to metabolic changes of the whole organism significantly greater than reactions of such forms as aggression, run away or stand still.

The investigations of stress response in laboratory animals preferably is exercised in different series of experimental models of stress, but not enough research is done on metabolic levels of changes in animals at pre-slaughter period. That is why the purpose of our investigations was: to determine some biochemical parameters changes of laboratory animals’ blood under pre-slaughter stress conditions. The results of determination of biochemical indices (cortisol concentration, protein fractions, activity of alanine and aspartate aminotransferase, total protein, hemoglobin content, erythrocyte count) of stress response in the laboratory animals blood before slaughter are presented in the paper.

Object and research methods. The experiment was conducted on 15 white laboratory mature Wistar female rats weighing 180–220 g with standard diet. The rats were kept under standard vivarium conditions in compliance with the 12-hour mode light dark/ light at the temperature of 20–22 °C and free access to drinking water and food. Three groups of rats one month of age (five rats each) was formed for research. The rats of each cage were taken both at one time and alternately – from the first to the fifth animal. Feeding of rats was done on a daily basis. The rats ate food completely. Decapitation was performed under ether anesthesia. Blood samples were taken from the area of decapitation. The rats slaughter was carried out in the morning. The blood plasma protein fractions separation was carried out by horizontal electrophoresis in polyacrylamide gel (PAAG). Cortisol level were determined in rats blood plasma using a set of ELISA (EIA-1887, Cortisol ELISA).

Mathematical treatment of the research results were processed statistically using the software package Statistica 6.0 and Microsoft Excel for Windows XP. Probability differences was assessed by Student t-test and results considered likely at p ≤ 0.05. Because of research it was found that the cortisol concentration reliable changes in the rats’ blood plasma depended on the order in which animals were taken from the cage (alternately from the first to the fifth animal) was determined. Herewith hormone level was ranged from 34.97 (the first animals from each cage) to 178.90 ng / ml (the fifth animals which were taken last from each cage). The cortisol level increased nearly by 1.5 times (p < 0.01) in the blood plasma of rats, which were taken fourth and fifth from each cage; cortisol level reliable increased nearly by 5 times (p < 0.05) in the blood plasma of rats, which were taken first and fifth which were last animals from each cage. The α-, β- and γ-globulins concentration reduced (p < 0.05) and albumin fraction concentration increased (p < 0.01) in the blood plasma of rats, which were taken last from each cage, was observed.

The results obtained in the model experiment can be used in research of cell immunity indices and stress hormones, such as cortisol, on farm animals for organism resistance increasing and correction of their pre-slaughter stress. The results provide an opportunity to create a biologically active food supplement and to substantiate the necessity ecological and safe animal production obtaining for human needs. These research results are promising.

Keywords: rats, pre-slaughter stress, cortisol, protein fractions

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