Nitrate detoxification of drinking water by ascorbic acid in growing rabbits

This work was carried out to study the capacity of ascorbic acid for detoxification of drinking water nitrate in growing New Zealand White rabbits. Forty growing female rabbits were assigned to five groups (8 rabbits/group). The control animals (group 1) drank tap water without nitrate addition, those of group 2 drank water with 729 mg/l nitrate, while rabbits of groups 3, 4 and 5 drank water with the same nitrate level plus 100, 200 and 400 mg/l ascorbic acid respectively for seven weeks. The nitrate caused a significant (P < 0.05) decrease in rabbit performance (feed and water intake, digestibility of nutrients and growth rate). Haemoglobin concentration, red blood cells count, total protein, albumin and globulin concentrations of animals drinking water with added nitrate decreased significantly (P < 0.05) but aspertate aminotransferase and alanine aminotransferase activities, blood urea and cholesterol concentrations increased significantly (P < 0.05). Daily weight gain decreased significantly (P < 0.05) in 5th, 6th and 7th weeks in rabbits treated with nitrate. The rabbits treated with nitrate had a significant (P < 0.05) worsening of feed conversion efficiency during the last three weeks of the treatment. The addition of ascorbic acid at three different levels (1100, 200 and 400 mg/l) caused significant (P < 0.05) increase in rabbit performance and led to an improvement of the measured blood parameters. In general, the results indicated that the highest level of improvement was obtained by adding ascorbic acid at the rate of 200 mg/l. The study also showed that 729 mg/l nitrate in drinking water had a toxic effect on rabbits. Ascorbic acid supplementation, especially at a level of 200 mg/l, was efficient and can be considered as a practical solution for nitrate detoxification of drinking water in growing rabbits.