Effect of Nitrate on the Body Weight, Food and Water Consumption and Thyroid Hormone in Hybrid Female Rabbits

摘要

Nitrate is a wide extend pollutant of ground and surface water. The objective of this study was to determine the effects of nitrate on the body weight, food and water consumption as well as thyroid hormone in hybrid female rabbits. Forty-five, six week-old of female New Zealand White rabbits were randomly assigned to five experimental groups according to concentration of nitrate in the drinking water (I- control, II, 64 mg/l, III- 78.2mg/l, IV- 144 mg/l and V-200 mg/l) for 15 weeks. Body weights as well as water and food consumption were determined weekly for each group, and blood plasma for Triiodothyronine (T3) and thyroxin (T4) levels were measured biweekly by enzyme immunoassay using ELISA. A significant dose-dependent decrease in the feed and water consumption was observed in young rabbits, as well as a sudden stop in increase in body weight at age of 12 weeks in rabbits exposure to 144 and 200 mg/l of nitrate and at age of 16 weeks in rabbits drinking water containing 78.2 and 64 mg/l, where, they start to become gradually decrease in their body weight as compare to control group in which they continue to increase until the end of experiment. The mean values of T3 and T4 were significant (P< 0.05) higher in control group as compare with other group. Moreover, the lowest value of T3 and T4 was observed in rabbit drinking water containing 200 mg/l. In conclusion, young rabbits drinking water with high concentrations of nitrate were found to effect the growth, body weight, water and food consumption as well as decrease in thyroid function in dose-depending manner.