Changes in the composition of milk and blood were studied from the sev
enth to the 170th days of lactation in ten time intervals (i.e. betwee
n 9 March and 29 August) in 22 ewes (12 of the Cigaya breed, and ten c
rosses with a 62.5 and 37.5% proportion of the Cigaya and East Friesia
n breeds, respectively). There were variations in the concentrations o
f milk constituents, the highest in somatic cell counts (153.6%), vita
min A (73.7%) and Cu (62.8%). Variable blood indicators were urea (50.
3%), vitamin E (37.9%) and Zn (22.1%). When estimating interrelationsh
ips between selected blood and milk indicators, the effect of stage of
lactation was not taken into account. The highest correlation coeffic
ients were between urea in blood plasma and milk (r = 0.90(++)). The c
orrelations between level of milk fat to total blood plasma protein, v
itamin E, vitamin A, pH of blood and plasma urea were r = 0.56(++), r
= 0.46(++), r = 0.33(++), r = 0.43(++), and r = 0.33(++), respectively
. Mineral levels in milk were less dependent on the metabolic profile
of the blood: the most significant relationships were for Cu and Zn in
milk. The most important macroelements of milk, Ca and P, were not si
gnificantly influenced by nutrition. The relationships between the lev
els of the majority of minerals in blood plasma and in milk, with the
exception of K, were significant.