Performance, Nutrient Digestibility and Nutrient Balance in Weaned Pigs Fed Diets Supplemented with Antibiotics or Zinc Oxide
Philip A. Thacker
An issue with feeding pharmacological levels of zinc to pigs is that application of their manure to soil can negatively impact the environment and therefore, it would be desirable if the beneficial effects of feeding zinc oxide could be obtained at lower levels of zinc supplementation. Three experiments were conducted to determine the effects of feeding a basal diet fed without supplementation (negative control) or the basal diet supplemented with either an antibiotic combination (33 ppm tiamulin and 100 ppm chlortetracycline; positive control), as well as 1500 or 2500 ppm zinc on performance, nutrient digestibility and zinc balance in weaned pigs. Two growth trials demonstrated improved performance for pigs fed zinc supplemented diets compared with the negative control. In both experiments, the performance of pigs fed zinc supplemented diets was essentially equal to that of the antibiotic supplemented pigs indicating that zinc can substitute for antibiotics in diets fed to nursery pigs. In addition, our data indicate that feeding 1500 ppm zinc resulted in similar performance to feeding 2500 ppm zinc. There was no effect of dietary zinc or antibiotic addition on the digestibility of dry matter, crude protein, calcium, phosphorus or energy. The concentration of zinc in feces was significantly higher for the zinc supplemented pigs than for pigs fed either the negative control or the antibiotic supplemented diet. However, the concentration of zinc in the feces of pigs fed 1500 ppm zinc was approximately half that of pigs fed 2500 ppm zinc. Our finding that feeding 1500 ppm zinc supported a similar level of performance as 2500 ppm zinc, while significantly reducing fecal zinc excretion indicates that it may be possible to reduce the levels of zinc in nursery diets without having to sacrifice performance while, lessening the environmental impact of manure disposal.