Zinc citrate influence on the concentration of some macro- and microelements in rabbit body tissues

Background. Some of the humanity’s problems in the 21st century are related to insufficient mineral nutrition according to the World Health Organization. The reason for this conclusion is not in the amount of mineral substances supplied with food, but in their bioavailability in the body. The problem of rabbit high-quality mineral nutrition is not solved during industrial maintenance. Research on the impact of organic compounds of trace elements on the human and animal body has intensified over the last decade. Studies show the effectiveness of the use of organic compounds of microelements with unique physiological properties to penetrate the cell and exert an activating effect on the course of biochemical reactions, which positively affects the whole organism. However, the physiological effect occurs under the condition of receiving and assimilation of organic compounds of trace elements in optimal amounts. Therefore, the main task of this research was to study the effect of the investigated doses of zinc citrate, which was fed in rabbits for 36 days after weaning to assess the change in the content of minerals in the tissues of their body.Materials and Methods. Studies were conducted on 16 rabbits that were close by clinical and visual indicators aged 40 days from birth, kept in a laboratory room of a research institution equipped with mesh industrial cages for rabbits. Rabbits of the control group were kept with free access to complete nutrient and mineral supplementation in feed and water. The animals were kept separately in cages and an appropriate amount of zinc citrate was added to the daily amount of water (100 mL) every day. Rabbits of this age drink an average of 100 mL of water per day. Rabbits of study groups I, II, and III used the same feeding as in the control, in addition, for 24 hours, zinc citrate was additionally used with water in the amount of: I – 0.25; II – 0.50; III – 0.75 mg Zn/kg of body weight. The comparative period was 10 days, the experimental period was 36 days. On day 36 of the study, animals of all groups were euthanized; their blood and tissues: liver, kidney, ribeye, spleen, and hair from the thigh area of rabbits were taken to determine the content of mineral elements using an atomic absorption spectrophotometer.Results. Feeding zinc citrate with water in the amount of 0.25 mg Zn/kg of body weight was marked by a probable increase in the content of Co and Cu (P <0.05) in the blood. Administration of zinc citrate in the amount of 0.50 mg Zn/kg of body weight was characterized by a probable increase in Zn (P <0.001), Co (P <0.001), Fe (P <0.05), Cu (P <0.05) in the blood; the level of Z (P <0.05), Cr (P <0.05), Co (P <0.01), Fe (P <0.05), Cu (P <0.01) in the liver; Fe (P <0.05) and Cu (P <0.05) in the spleen, Zn (P <0.05) in muscle and hair compared to control. The use of zinc citrate at the rate of 0.75 mg Zn/kg of body weight induced the most probable changes: the content of Zn (P <0.01) in the blood, liver (P <0.05), spleen (P <0.01), muscle (P <0.05) and hair (P <0.01), Cr in the liver (P <0.05), Co in the blood (P <0.01), liver (P <0.01), spleen (P <0.01), Fe (P <0.01) and Cu (P <0.05) in the blood, liver (P <0.05–0.01), kidneys (P <0.05–0.01), Fe in the spleen (P <0.01) and muscle (P <0.05) compared with the control group.Conclusions. Additional administration of zinc citrate (0.25 mg Zn/kg body weight) with water for 36 days was marked by the smallest changes in the studied mineral substances concentration of rabbits’ tissues, with the exception of an increase in the Co and Cu blood content. With an increase in the daily amount of zinc citrate (0.50 and 0.75 mg Zn/kg body weight), the concentration of Zn, Co, Fe, and Cu in the blood and liver tissue mainly increased, while less prominent changes were noted in the tissue of the spleen and kidneys compared to the control group. Macro- and microelements concentration changes may indicate a more pronounced effect of zinc citrate depending on the applied amount, in particular, a larger amount (0.75 mg Zn/kg body weight) induced the greatest probable increase in the studied microelements, with the exception of Mg and Mn in the rabbits’ body tissues.