SELECTED MINERAL PROFILE INDEXES OF BLOOD -SERUM OF SHEEP IN THE SINGLE PHASES OF THE REPRODUCTIVE-CYCLE

In animal organisms, mineral substances are controlled by complex home ostatic mechanisms. Changes of mineral substance concentrations interv ene in the metabolism of myometrial and endometrial structures (B i t m a n et al., 1961). Significant changes of sodium, and mainly potassi um, levels during pregnancy were observed in cows (S c h v a r c , 196 5) and ewes (S o b i r a j et al., 1986). Changes of the Ca : P ratio in the blood serum of cows were reported in relation to fertility as w ell as in the puerperium (G a r b a c i k , B a I o n , 1978; K u d l a c , 1985, respectively). The present work was aimed at the observati on of dynamic changes in selected indices of the mineral profile in th e single phases of the reproductive cycle. Ten Slovak Merino sheep age d 3 - 5 years and weighing 40 - 50 kg were used in an experiment. The animals were kept on a commercial farm and fed according to the Czecho slovak State Standard CSN 47 7070. Blood samples were taken from the v . jugularis prior to oestrus synchronization (day 0) and on days 3, 7 and 14 after insertion of the Agelin vaginal tampons. After tampon rem oval the sheep were given 500 IU PMSG per animal. Blood sampling was c ontinued on the day of insemination and on days 7, 14 and 17 after ins emination; during pregnancy four samplings were carried out. After lam bing, blood samples were again taken in 36 hs p.p. and on days 4, 7, 1 4, 17, 21, 34, 42 and 51. Ca and P levels were determined using the Bi ola tests (Lachema, Brno) while an atomic absorption spectrophotometer Atomsek (RANG-HIGLER) was used for Na and K determinations. Sodium le vels (Fig. 1, Tab. I) revealed a significant decrease between insemina tion and month 2 of pregnancy (P < 0.01 and P< 0.001, respectively). N o significant changes were observed in the puerpenum; serum levels of sodium varied between 154.8 +/- 6.0 and 147.7 +/- 6.79 nmol.l-1(until day 17 p.p.) and 146.7 +/- 10.71 and 157.20 +/- 5.15 nmol.l-1 (until d ie end of die period under observation). Potassium levels significantl y decreased on the day of insemination (P < 0.01) and continued to dec rease on the given days of pregnancy (P < 0.001), reaching the values between 3.89 +/- 0.19 and 4.57 +/- 0.52 nmol.l-1 serum. In the postpar tal period, potassium concentrations varied between 4.78 +/- 0.64 and 5.69 +/- 0.80 nmol.l-1, with the level of significance established at P < 0.05 and P < 0.01 on day 1 and days 7 and 34, respectively. The dy namics of Na and K level decrease in the given period is possibly rela ted to the increased permeation of mineral substances into the uterine environment which is the only source of foetal nutrition in the first days of pregnancy (K u d l a c , E l e c k o , 1977). As evidenced by Fig. 3 and Tab. II, decreased Ca levels were recorded between insemin ation and month 4 of pregnancy (2.53 +/- 0.2 to 2.11 +/- 0.12 nmol.l-1 ) and in the postpartal period (2.52 +/- 0.17 to 2.21 +/- 0.14 nmol.l- 1). A similar decrease in P levels was observed between insemination ( P < 0.01) and month 1 of pregnancy (P < 0.001). From day 17 on, the pu erperal concentrations of Ca varied between 1.70 +/- 0.27 and 1.93 +/- 0.17 nmol.l-1 serum. In our opinion the Ca and P levels recorded duri ng prepancy depended on the permeation of nutrient substances from mat ernal blood into the foetus. The post partum concentrations of these e lements coincided with the values found by K u d l a c (I 985) and J e l i n e k et al. (I 985) in puerperal cows and pregnant and lactating ewes, respectively. The dynamic changes in the above indices of the m ineral profile point at the important role die latter plays in the com plex homeostatic and neurohumoral mechanisms that affect the single st ages of the reproductive cycle of sheep.