Institute of Animal Science, BG - 2232 Kostinbrod, Bulgaria
DYAVOLOVA, M., 2014. Trace elements content of m. biceps femoris and liver in rabbits exposed to direct solar radiation. Bulg. J. Agric. Sci., 20: 210-214
This investigation was initiated to study the effect of solar radiation on the content of some trace elements in liver and muscle tissue as potential heat stress indicators. Twelve New Zealand rabbits at the age of 4 months were allocated into 2 groups – control (no direct solar radiation, temperature range 24-27°C) and experimental (heat stressed) rabbits. Experimental rabbits were exposed to direct solar radiation for 4 hours (30 - 35°C) without any access to food and water. Blood samples were taken immediately before the start of heat exposure and 2 hr following the heat stress by ear venepuncture. At the end of the stress period, the animals of both groups were slaughtered and liver and m. biceps femoris samples were taken and analyzed for trace elements. Rectal temperature was measured prior to blood sampling. Exposure of rabbits to heat caused significant increase in liver content of Na (p<0.01), Cr (p<0.01) and Cu (p<0.01), but had no effect on muscle concentration of Na, K, Cr, Fe, Zn, Cu and Se. Control rabbits had higher concentration of Na, Fe, Zn, Cu and Se in liver than in muscle (p<0.001). Muscle potassium concentration exceeded that in the liver (p<0.001) of control rabbits. Muscle sodium to potassium ratio was almost 3 times lower than that in the liver of control rabbits. Heterophil to lymphocyte ratio increased significantly in experimental rabbits (p<0.01) thus showing that rabbits under heat experienced significant stress load. The results were interpreted to assume that heat induced liver lipid peroxidation and the possible increase in the portion of the unbound copper are the main metabolic changes which have adverse effect on liver function.