Calculation of pollutants producing and discharging coefficients of heifers and lactating dairy cows in large-scale dairy farms

To provide basic parameters for environmental engineering facilities in large-scale dairy farms, the pollutants producing and discharging coefficients in heifers and lactating dairy cows were assessed for large-scale dairy farms in Heilongjiang province. The results showed that the pollutants producing coefficients of feces, urine, chemical oxygen demand(COD), total nitrogen(TN), total phosphrus(TP), Cu, and Zn for each heifer were15.77 kg/d, 7.23 L/d, 2 132.49 g/d, 112.82 g/d, 50.28 g/d, 96.04 mg/d, and 461.89 mg/d, respectively; and those for each lactating dairy cow were 33.47 kg/d, 16.34 L/d, 4 265.58 g/d, 270.88 g/d, 182.99 g/d, 196.34 mg/d, and 979.09 mg/d, respectively. The pollutants discharging coefficients of COD, TN, TP, Cu, and Zn for each heifer were 540.39 g/d, 34.34 g/d, 13.29 g/d, 18.37 mg/d, and 91.06 mg/d, respectively; and those for each lactating dairy cow were 1 000.58 g/d, 85.29 g/d, 59.65 g/d, 39.64 mg/d, and 213.31 mg/d, respectively. The rate of fecal collection for heifers and lactating dairy cows were 73.31% and 69.93%, respectively. About 20%-30% of pollutants produced by large-scale dairy farms were leaked into environment in Heilongjiang province.