By Casey Bradley, Swine Technical Manager, AB Vista
Zinc is an essential trace element in all living systems, and most enzymes in the pig require Zn for either structure or function. Zinc deficiency leads to poor growth performance and feed intake and can cause parakeratosis. Pharmacological levels of Zn (2,000-3,500 ppm) are often used from weaning up to 21 days post-weaning to help prevent diarrhea and improve growth performance, with some trials showing a 20% improvement in ADG with 2,500 ppm of Zn. However, phytate, the primary storage form of phosphorus for plants, chelates minerals, including Zn, rendering them unavailable for absorption by the animal. Undigested minerals are excreted in manure resulting in excess mineral levels in the soil that can cause contamination of water streams and environmental pollution.
Reducing Zn levels in the nursery to reduce environmental impact without negatively impacting post-weaning performance is of significant interest. This can be achieved by reducing phytate using phytase superdosing. This application increases the bioavailability of Zn, allowing for reductions in dietary ZnO supplementation whilst reducing fecal scours and maintaining piglet growth.
Phytase superdosing involves the use of a highly efficient phytase to target near complete phytate destruction for maximum mineral absorption and performance benefits. Five trials conducted with Quantum Blue phytase, fed at 2,500 FTU/kg from weaning to 21 days post-weaning demonstrated the impact of superdosed phytase and Zn on piglet performance.
The addition of superdosed phytase improved performance, fed in combination of any level of Zn (0-3,500 mg/kg), by 10-30% with the highest ADG at 30% obtained at medium levels of Zn (1,750-2,500mg/kg) with superdoses of Quantum Blue. This suggests that even when Zn was reduced from high to medium supplementation, growth rate was improved beyond that of the high Zn diet alone.
This shows that the level of pharmacological Zn may be reduced by 500-750 ppm in the presence of superdosing phytase without affecting performance. In comparison to a non-phytase diet, superdosing phytase at 2,500 FTU/kg in post-weaned pigs resulted in increased serum Zn, indicating an improvement of Zn utilization which may in part explain the growth performance benefit as well as the reduction in post-weaning scour.
For the anti-nutrient effects of phytate to be eliminated, 80-85% of total phytate typically needs to be degraded. Understanding the relationship between phytate, phytase and Zn is important in optimizing the post-weaning performance of pigs with phytase superdosing and pharmacological Zn levels. Lower levels of pharmacological Zn may be an option in the future to maximize post-weaning performance using phytase superdoses.
Optimal phytase characteristics
- Intrinsic thermostability
- Efficacy early in the gastrointestinal tract at low pH
- High activity at low substrate concentrations