The research deals with the integral haematological indices such as markers of immunoreactivity and phagocytic activity of neutrophils in animals kept in conditions of a nutrient imbalance. The animals were divided into four experimental groups: I — animals receiving full-value semi-synthetic ration (control group); II — animals receiving low-protein ration (LPR); III — animals receiving high-sucrose diet (HS); IV — animals receiving low-protein/high-sucrose diet (LPR/HS). It has been found that in animals kept in conditions of nutritional protein deficiency there was a disturbance of the specific immune response, as evidenced by a decrease in the immunoreactivity index and an increase in the index of neutrophils and leukocytes ratio. At the same time, no significant changes in the index of blood leukocytes shift and phagocytic activity of neutrophils were found, indicating the preservation of the non-specific immune response activity. However, in animals of this experimental group compensation of endotoxemia and a decrease in the adaptation index were observed, indicating an inhibition of the adaptive mechanisms. Similar changes in the integral haematological indices were observed in animals kept on a high-sucrose ration. It has been shown that animals consuming a low protein/high-sucrose ration have low immunological reactivity, as evidenced by a 3.4-fold decrease in the immunoreactivity index and a 1.5-fold increase in the blood leukocyte shift index, and disturbances in specific immune response (marker is an increase in the neutrophils and lymphocytes ratio), as well as a significant decrease in the phagocytic index, indicating the ineffectiveness of immune reactions involving neutrophils. At the same time, the intensification of the adaptive mechanisms and a three-fold increase in the reactive neutrophil response index indicates the subcompensation stage of endotoxemia. It is concluded that studied integral haematological parameters can be used as additional early diagnostic markers of impaired immunoreactivity and endotoxemia in animals kept in conditions of different protein and sucrose content in the diet.