Effects of dietary supplementation of nickel and nickel-zinc on femoral bone structure in rabbits

BACKGROUND Nickel (Ni) and zinc (Zn) are trace elements present at low concentrations in agroecosystems. Nickel, however, may have toxic effects on living organisms and is often considered as a contaminant. This study reports the effect of peroral administrated Ni or a combination of Ni and Zn on femoral bone structure in rabbits. METHODS One month-old female rabbits were divided into three groups of five animals each. Group 1 rabbits were fed a granular feed mixture with addition of 35 g NiCl2 per 100 kg of mixture for 90 days. In group 2, animals were fed a mixture containing 35 g NiCl2 and 30 g ZnCl2 per 100 kg of mixture. Group 3 without administration of additional Ni or Zn served as control. After the 90-day experimental period, femoral length, femoral weight and histological structure of the femur were analyzed and compared. RESULTS The results did not indicate a statistically significant difference in either femoral length or weight between the two experimental groups and the control group. Also, differences in qualitative histological characteristics of the femora among rabbits from the three groups were absent, except for a fewer number of secondary osteons found in the animals of groups 1 and 2. However, values for vascular canal parameters of primary osteons were significantly lower in group 1 than in the control one. Peroral administration of a combination of Ni and Zn (group 2) led to a significant decreased size of the secondary osteons. CONCLUSIONS The study indicates that dietary supplementation of Ni (35 g NiCl2 per 100 kg of feed mixture) and Ni-Zn combination (35 g NiCl2 and 30 g ZnCl2 per 100 kg of the mixture) affects the microstructure of compact bone tissue in young rabbits.