The aim of the study was to determine the concentration of Ca, P_ig and Mg in osseous tissue of the lambs of various breeds at age of 14 days. The studies were carried out on 217 lambs in various sheepfolds in Northwest Poland. The material for the studies comprised the osseous tissue ash of the 4th and 5th caudal vertebrae. The values of macroelement concentrations in osseous tissue were expressed in mmol l^-1 in 1 g of dry matter. The highest osseous tissue concentration of Ca was found in the lambs: Blackhead (19.74 mmol l^-1 ± 2.02) and Leine (15.94 mmol l^-1 ± 3.16). The lowest Ca was recorded in the lambs Romney Marsh (9.50 mmol l^-1 ± 1.80) and Merino (10.25mmol l^-1 ± 4,84) The lowest P_inorganic. concentration was found in the osseous tissue of the Polish Merino (11.43 mmol l^-1 ± 1.18). The concentration of Mg ranged between 0.82 mmol l^-1 ± 0.10 in the bone tissue of Merino lambs and 1.10 mmol l^-1 ± 0.21 in the bone tissue of the crossbreds Polish Merino x Suffolk lambs. The lowest Ca:P ratio was observed in the osseous tissue of the Romney Marsh lambs (0.50 ± 0.10), whereas the highest was found in the Blackhead lambs (1.17 ± 0.17). A wide range (p≤ 0.01) of the Ca:Mg ratio were recorded, from 11.40 ± 1.72 in Romney Marsh to 20.37 ± 2.09 in Blackheaded. The analysis of the results obtained from the studies of mineral composition of the lamb tail vertebrae osseous tissue demonstrated that the factor of the breed and the breed-related purpose type were the background of the differences between the lambs, and that the differences may have been associated to geochemical factors.

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