Abstract
The study was carried out to investigate the effect of nitrate supplement in drinking water on the nitrate balance, reproduction performance, nitrate levels in plasma, and on milk and stomach contents of pups in rats.
Wistar femal rats were fed ad libitum a commercial diet (CE II-Crea) and drinking water containing 40, 80 and 1, 000 ppm of nitrate nitrogen for 7 weeks and mated at the age of 15 weeks. On the day 14 postpartum, maternal blood and milk, stomach contents and blood of pups were examined.
The results obtained were as follows: Daily intake of nitrate nitrogen per 100 g body weight were 14μg, 436μg, 900μg and 10, 310μg in control group, 40, 80 and 1, 000 ppm groups respectively, and roughly 55-65% of ingested nitrate were excreted in the urine within a 24-hr period. Therefore, it appeared that about 35-45% of administered nitrate retained in the body.
In the 1, 000 ppm dose group, remarkable effects of nitrate intake on the fertility index, normal gestation ratio, number of pups delivered and pups alive at day 4 of lactation were observed. The nitrate levels in plasma, milk and stomach contents of pups were elevated with increase of nitrate intake. When the drinking water was taken with 1, 000 ppm nitrate, the nitrate plus nitrite nitrogen concentration of maternal plasma, milk and stomach contents of pups rose to 12.8±1.3μg/ml, 15.5±0.9μg/g and 27.1±4.1μg/g, respectively. Since milk/maternal plasma ratio for nitrate in all group was approximately 2, the mammary gland appeares to concentrate nitrate.
