[Transmammary transfer of nitrates and nitrites in ruminants and methemoglobin blood levels in the young and their mothers].

Transmammary transfer of nitrates was studied in ewes as model animals and in a dairy cow during the colostrum period and shortly after it. Ewes were administered per os 35 mg NaNO3.kg-1 of live weight twice daily during five days post partum and the dairy cow 50 g KNO3 during ten days post partum. Methaemoglobinaemia in ewes and their lambs had consistent dynamics during the whole period of study with slightly higher values in lambs than in ewes. Differences in the averages of methaemoglobin (MtHb) concentrations in blood were statistically higher from the fourth till the 72nd hour after administration. NaNO3 concentration in milk highly and significantly increased after the first administration, with a subsequent decline to an insignificant level during further clays, as compared with the initial data. NO2 ions were not observed to be present in any milk sample. Dynamics of methaemoglobinaemia in the dairy cow and her calf was the same as in the ewes, with a tendency of regular increasing four hours after administration. The increase in methaemoglobinaemia the last day of the trial was at the limit of significance. NaNO3 content in milk significantly increased on the 3rd, 9th and 10th day after administration. Nitrates in urine showed similar trend as in milk with a significant increase only on the 2nd and 10th day post partum. The finding of 14.5 mg.l-1 NaNO3 in the amniotic fluid provides evidence of a simultaneous transplacental transfer of nitrates.