PSXIII-10 Effects of nitrate concentration in drinking water on water and feed consumption, total tract digestibility and health implications in Holstein bulls fed high-concentrate diets

Abstract

Abstract The aim of this study was to evaluate the effect of nitrate concentration in drinking water on water and feed consumption, total tract apparent digestibility and its potential toxicity on animal health in fattening Holstein bulls. Twenty-four Holstein bulls (161 ± 19.9 kg of initial BW, and 183 ± 25.3 d of age) were housed individually and fed ad libitum. Animals were assigned to 4 treatments according to nitrate concentration in drinking water: 0, 44, 110 and 220 mg / L. The different nitrate concentrations were achieved by the addition of different potassium nitrate 0.22 M doses. Water consumption and animal health status was recorded daily. Every 2 wks feed consumption, BW were recorded, and nitrate concentration in drinking water was analyzed by photometry. At d 0, 14, 112 and 168 blood samples were collected to determine ammonia and methemoglobin concentrations. At d 14 and 168 total tract apparent digestibility was estimated. Data were analyzed with a mixed effects model. Water consumption decreased (P < 0.05) when nitrate concentration in water was above ≥ 110 mg / L (30.2, 27.4, 24.4 and 26.4 ± 1.38 L/d for 0, 44, 110 and 220 mg/L nitrates in water, respectively). Water nitrate concentration did not affect serum ammonia and methemoglobin concentration (58.0 ± 2.17 µmol / L and 2.4 0.09 %, respectively). In addition, water nitrate concentration did not affect performance, total DMI, and nutrient digestibility. Drinking water for a long period with nitrate concentrations up to 110 mg/L did not have detrimental effects on performance and health. Beyond this threshold a reduction of water consumption of 16 % was observed and blood parameters (methemoglobin) and health registers did not indicate that the concentration of 220 mg/L of nitrates in drinking water may have health side-effects in fattening bulls fed high-concentrate diets.