New Applications such as Superdosing of Phytase to Maximize Phytate Destruction to Improve Performance while Minimizing Nutrient Excretion in Poultry
By C. L. Walk and T. York, AB Vista
It is well documented that phytase supplementation in broiler diets improves P and Ca utilization through the destruction of phytate (IP6) and thereby allows for the reduction of inorganic phosphate in the diet. Phytase is supplemented in approximately 95% of the poultry diets globally with the majority of the use associated with reduced diet cost and reduced phosphorus (P) excretion. For the purpose of this paper, this type of phytase supplementation will be referred to as the standard dose of phytase, normally around 500 FTU/kg. Superdosing is a relatively new term used to describe phytase
supplementation at ≥ 1,500 FTU/kg (Walk et al., 2014) or ≥ 2,500 FTU/ kg (Adeola and Cowieson, 2011). This is predominantly associated with improvements in feed efficiency by 3-5 FCR points (Walk et al., 2013, 2014) through the rapid and nearly complete destruction of IP6 and the provision of inositol (Adeola and Cowieson, 2011; Walk et al., 2014). Through near complete destruction of IP6, more P is released from the phytate molecule, and other nutrients such as iron (Fe), zinc (Zn), copper (Cu), and sodium (Na) become more available to the animal as well. Therefore, superdoses of phytase could have multiple uses towards achieving sustainable poultry
production; this is associated with improvements in feed efficiency, mineral utilization, and poultry products, with specific consideration regarding fast growth, minerals and breast meat myopathies.
Superdoses of Phytase Feed Efficiency Superdosing phytase has been defined as supplementing phytase greater than 2 to 5 times the standard phytase dose without taking the full nutrient matrix. Published data has indicated supplementing broiler diets with superdoses of phytase (1,000 or 1,500 FTU/kg) significantly improved feed conversion ratio of 35- (Santos et al., 2013) or 49-day-old broilers (Walk et al., 2013; Table 1). However, there was no significant effect of superdoses of phytase on feed intake or BW gain (Santos et al., 2013; Walk et al., 2013, 2014), and no effect of additional dietary inorganic P on performance or feed efficiency (Walk et al., 2013, 2014). Therefore, the influence of superdoses of phytase on FCR can be described as ‘extra-phosphoric’ and has been loosely correlated with the near complete destruction of phytate into inositol in the gizzard (Walk et al., 2014; Table 1).
Table 1: Influence of Superdoses of Phytase on Broiler Performance from Hatch to Day 49 Post-hatch and Gizzard Phytate or Inositol Concentration on Day 21
Experimental diets PC3
PC + dicalcium PO4 PC + 500 FTU/kg
NC4
NC + 500 FTU/kg NC + 1,000 FTU/kg NC + 1,500 FTU/kg SEM
P-value Intake1 , g
6,371 6,444 6,430 6,240 6,344 6,378 6,350 81
0.69
1 Adapted from Walk et al., 2013. 2 Adapted from Walk et al., 2014.
Negative control, nutrient adequate according to breed recommendations with the exception of Ca, available P, and Na which were reduced 0.16, 0.15 and 0.03%, respectively.
3 Positive control, nutrient adequate according to breed recommendations. 4
PAGE 42 MAY/JUNE 2017 FEED COMPOUNDER BW gain1
3,475 3,453 3,539 3,462 3,497 3,529 3,551 55
0.80 , g FCR1 , g:g
1.835ab 1.868a 1.817bc 1.834ab 1.815bc 1.808bc 1.790c 0.015 0.01
Gizzard Phytate (IP6)2
, µmol/g
2.85ab 3.93a 0.21c 1.91b 0.04d 0.00d 0.00d 0.02
0.0001
Gizzard Inositol2 µmol/g
0.91c 0.88c 1.15bc 1.21b 1.57b 2.12a 2.22a 0.10
0.0001 ,
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