Influence of increasing pharmacological ZnO dose to 3500 ppm and superdoses of phytase on piglet growth performance and fecal scores from d 0 to 21 post-weaning

Abstract Text: Pharmacological zinc oxide (ZnO) reduces fecal scours in piglets. However, the level of ZnO supplemented can vary between 2000 and 4000 ppm depending on country, piglet age and veterinary restrictions. One main experiment was conducted to evaluate pharmacological levels of ZnO in the presence or absence of superdoses of phytase (Quantum Blue). This abstract is 1 of 2 and will focus on ZnO levels typically fed in the non-European markets (up to 3500 ppm). Piglets (n=640) were weaned at approximately 18 to 21 d of age (5.2±1.02 kg) and allocated at 10 pigs/pen and 8 replicate pens/treatment. Piglets were fed one of 8 diets formulated to be adequate (NRC, 1998) in all nutrients including available phosphorus (0.55%) and calcium (0.89%). Zinc supplemented in the diets, above pre-mix levels (100 ppm), was from ZnO (72% Zn). The 8 diets were as follows: 1750 ppm Zn plus 0, 1250, 2500 or 3750 FTU/kg phytase or 3500 ppm Zn plus 0, 1250, 2500 or 3750 FTU/kg phytase. Fecal scores were obtained from d 1 to 10 on a scale from 1 to 4 with 1 = firm and 4 = watery. Statistical analyses were performed using JMP. The model included diet, replicate pen and block and significant means were separated using t-tests. ADFI was lowest (P<0.05) in pigs fed 1750 or 3500 ppm Zn plus 0 or 1250 FTU/kg phytase compared with pigs fed 3500 ppm Zn plus 3750 FTU/kg phytase. Phytase supplementation at 2500 or 3750 FTU/kg tended to increase (P<0.07) ADG, especially in pigs fed 3500 ppm Zn compared with pigs fed 1750 ppm Zn without phytase. Feed conversion ratio was not influenced by diet from d 0 to 21. Fecal scores were generally low and ranged from 1 (firm) to 2.5 (soft, spreads slightly) from d 1 to 10. However, fecal scores were the highest (P<0.001) in pigs fed 1750 ppm Zn without phytase compared with pigs fed 1750 ppm Zn plus 1250 or 3750 FTU/kg phytase or 3500 ppm Zn plus 1250, 2500 or 3750 FTU/kg phytase. In conclusion, phytase supplementation improved ADG and reduced fecal scores in piglets fed 1750 or 3500 ppm Zn from ZnO.

Keywords: phytase, piglets, zinc oxide