The influence of the reproductive cycle on levels of some metabolism indices in ewes.

Investigations were performed in 14 ewes of the Polish Merino race, undergoing the second reproductive cycle. Fundamental indices of the protein and energy metabolism, levels of Ca, P, Mg, Cu, Fe and beta-carotene as well as vitamins A, E and C in the blood plasma and serum were determined. The analyses were carried out during the following periods of the reproductive cycle: 3 weeks before mating, the early and late pregnancy, the culmination and close of lactation. The levels of metabolism indices, especially those of the protein and energy metabolism, were found to vary during the studied periods of the reproductive cycle. In all the periods, low levels (during lactation a deficiency) of Ca and Mg and a distinct deficiency of vitamin C were detected. It seems therefore, necessary to work out the reference values for particular periods of the reproductive cycle.