[Effects of the addition of increased nitrates to the drinking water of fattening pigs and weaned piglets].

Three experimental studies were done on the effects of increased concentrations of nitrate in the drinking water of weaned piglets and flattening pigs throughout the weaning and fattening periods respectively on the experimental piggery in Raalte for pigs in the northern and eastern Netherlands. To begin with, prospective studies were done in three times four individually housed experimental animals which were given 100, 200 and 500 mg of nitrate per litre of drinking water respectively throughout the fattening period. The results obtained were compared with the findings in twenty controls. When the weaned piglets were studied, two groups of weaned piglets, each consisting of an odd hundred piglets, fifty per cent of which served as an experimental group, the other fifty per cent serving as a group of controls, were compared. The experimental group was given drinking water to which 220 mg of nitrate per litre were added. When the fattening pigs were studied, two groups, each consisting of seventy animals, were compared. Fifty per cent served as a control group and fifty per cent as an experimental group. The experimental groups were given drinking water to which 500 mg of nitrate per litre were added. The nitrate and nitrite levels of the drinking water supplied were measured at regular intervals. The studies in fattening pigs included the examination of blood samples for the concentrations of haemoglobin and methaemoglobin halfway and at the conclusion of the periods. The additional nitrate in the drinking water did not have any negative effect on the haemoglobin and methaemoglobin levels of the drinking water or on the results obtained in these studies. Studies on meat and organs were done in five controls and five experimental animals from the fattening pigs studied. Marked differences were not observed in any case. It is concluded that an increased concentration of nitrate in drinking water does not have any injurious effect on the health of and the results obtained in weaned piglets, provided the drinking water is of good quality in addition to having an increased nitrate level.