Effects of dietary zinc supplementation on broiler performance and nitrogen loss from manure

An experiment was conducted to evaluate the effects of ZnSO₄ or ZnO supplementation of broiler diets on growth performance and loss of uric acid N and total N from manure. A total of 240, 1-d-old broiler males were used for this experiment. Each dietary treatment was replicated 3 times with 10 birds per replicate. Chicks were fed a control diet for the first 6 d and then treatment diets for the next 12 d. There were 8 dietary treatments: the control, CuSO ₄-20, ZnSO₄-500, ZnSO₄-1,000, ZnSO ₄-1,500, ZnO-500, ZnO-1,000, and ZnO-1,500 containing 0, 0, 500, 1,000, 1,500 ppm supplemental Zn as ZnSO₄ and 500, 1,000, and 1,500 ppm supplemental Zn as ZnO, respectively. A 300-g sample of the broiler manure from each treatment was incubated in a pan for 3 wk at room temperature. After incubation, samples were collected for the measurement of total N and uric acid N. Weight gain, feed consumption, and feed efficiency of chicks fed the diets supplemented with 1,500 ppm Zn as ZnSO₄ were significantly lower than those of the other treatments, whereas the ZnO treatments had no negative effects on growth performance. After the 21-d incubation, the uric acid-N levels of manure from chicks fed the ZnO-1,000 treatment were significantly higher than those of manure from chicks fed the ZnSO₄-500. The manure from chicks fed the Zn-supplemented diets had significantly less total N loss compared with that from chicks fed the control. The manure from chicks fed ZnO-1,500 had significantly less total N loss than that from chicks fed the other treatment diets. This study indicated that the Zn treatments significantly reduced nitrogen loss in poultry manure, and ZnO could be a better Zn source to prevent nitrogen loss to the atmosphere without any detrimental effect on growth performance.