Pharmacological ZnO dose and superdoses of phytase on piglet growth performance and cost of gain from d 0 to 21 post-weaning

Abstract Text: Feeding piglets pharmacological doses of zinc oxide (ZnO) has been shown to reduce fecal scours and improves ADG and FCR. However, the level of ZnO necessary to elicit a response may be reduced in the presence of superdoses of a novel third generation microbial phytase (Quantum Blue). An experiment was conducted to evaluate 4 doses of pharmacological ZnO (1250, 1750, 2500 or 3500 ppm) with or without 2000 FTU/kg of phytase on piglet performance and cost per/kg of gain from d 0 to 21 post-weaning. Diets were arranged as a 2 x 4 factorial and fed to 720 pigs, weaned at approximately 18 to 21 d of age, with 10 pigs/pen and 9 replicate pens/treatment. Diets were adequate in all nutrients, including available phosphorus (0.45%) and calcium (0.79%, NRC, 1998) and fed as one diet from weaning to 21 d post-weaning. When means were significantly different (P<0.10), the main effect of ZnO or phytase or the interaction was separated using t-tests. Feeding ZnO at 3500 ppm decreased ADFI (P<0.001) and ADG (P<0.01) compared to pigs fed all other ZnO doses from d 0 to 7. From d 14 to 21, ZnO supplementation at 1750 ppm increased ADG (P<0.05) compared to pigs fed ZnO at 2500 or 3500 ppm, but this was not different from pigs fed 1250 ppm ZnO. Overall (d 0 to 21), supplementation of ZnO at 1750 ppm tended to increase ADFI (P=0.07) and ADG (P=0.06) compared to pigs fed 2500 or 3500 ppm ZnO, but not pigs fed 1250 ppm ZnO. Phytase supplementation increased ADG (P<0.001) from d 7 to 14 and tended to increase ADG (P=0.10) from d 0 to 21. From d 7 to 14, there was a tendency for a phytase x ZnO interaction on FCR (P=0.07) whereas phytase improved FCR, especially in pigs fed 3500 ppm ZnO compared to all other treatments. Overall (d 0 to 21), phytase supplementation improved FCR (P<0.03) from 1.12 to 1.09. Phytase supplementation improved ADG and FCR which resulted in extra gain (0.26 kg) at the same cost/kg of gain as the non-phytase supplemented diets. In conclusion, ADFI and ADG were highest in pigs fed ZnO below 3500 ppm and phytase improved ADG and FCR from d 0 to 21 post-weaning.

Keywords: phytase, piglets, zinc oxide