The influence supplementing the micro-elements selenium, zinc and copper during drought feeding on ewe lambs has been studied. Certain parameters of the immune-system were studied at different times during the trial. The accumulation of the elements in the different tissues was investigated with specific emphasis on the accumulation of selenium in blood and plasma. Blood samples were collected on days 0, 1, 2, 4, 8, 16, 30, 60 and 90 to determine the peculiar way in which the selenium levels rise in the whole blood and plasma. Sodium selenite was used as source for selenium, zinc oxide as source of zinc and copper sulphate as source of copper. These three groups of chemical compounds were dosed to two groups of S. A. Mutton Merino lambs (two times a day). A third group of sheep was given only the basic diet which consisted of Smutsvinger hay. Salt and water were given ad lib to all three groups. The supplemented groups (groups 1 and 2) received 1.6 or 3.2 mg selenium/animal/day, 48.1 or 96.2 mg zinc/animal/day and 5 or 10 mg copper/animal/day, respectively. The two supplemented groups showed a tendency to heavier body weights than the control group, but the differences were not significant (P > 0.05). This could mean that the supplemented groups were healthier than the control group. The creatine phosphokinase (CK) and aspartate transaminase (AST) activities were significantly lower in the supplemented groups than in the control group (CK, P < 0.01 and AST, P < 0.05). This could mean the muscle cell membranes in the supplemented groups were better protected against degradation. There were a tendency for higher primary antibody production against bovine erythrocytes in supplemented groups than in the control group, but with no significant differences (P > 0.05). The selenium levels in tissues and blood (whole blood an plasma) were significantly higher in the supplemented groups than in the control group (P < 0.05). The selenium accumulation in the liver was exceptionally high, even higher than the selenium concentration in the kidneys, which is difficult to explain. Copper levels were significantly higher in group 2 than in the control group (P < 0.05). No significant differences were found between the groups when superoxide dismutase activities were studied (P > 0.05). The conclusion could be drawn that it is necessary to supplement micro-elements which will contribute to the antioxidant status of the animal especially in times of food scarcity and elevated stress in the animals. The supplementation will have a positive economical influence on the production (growth, health and reproduction) of the animal.
Dissertation (MSc (Animal Sciences))--University of Pretoria, 2006.