Effects of a Corn-Expressed Phytase on Growth Performance and Bone Ash of Nursery Pigs

This experiment was conducted to determine the optimum level of corn-expressed phytase (CEP; GraiNzyme® Phytase, Agrivida) by evaluating growth performance and metacarpal bone characteristics in nursery pigs fed phosphorus and calcium deficient diets. A total of 288 pigs were blocked by initial BW and allotted to 1 of 6 treatments (8 replicates per treatment). Pens were randomly assigned to dietary treatments. Treatments consisted of: P and Ca adequate diet (PC; NRC 2012); decreased P (0.15%) and Ca (0.1%) diet (NC), and NC plus 500, 1000, or 1500 FYT/kg of CEP or 500 FYT/kg of Ronozyme® Hiphos GT. Pigs were fed a common phase-1 (8d) diet before initiated treatments in phase-2 (14d) and 3 (14d). Pigs were euthanized at termination of phase-3 to collect metacarpal bones for ash determination. Data were analyzed by PROC MIXED procedures of SAS with treatments as fixed effect and initial BW block as random effect. Orthogonal contrasts were performed to determine the effects of increasing CEP. Increasing levels of CEP linearly increased overall ADG (P < 0.01), G:F (P < 0.05), end BW (P < 0.05), and percent bone ash (P < 0.01; Table 1). Pigs fed 500 FYT/kg of CEP had comparable (P > 0.05) or greater (P < 0.05) bone ash weight or percentage, respectively, as compared to pigs fed Hiphos GT. Pigs fed 1000 FYT/kg CEP had equivalent (P > 0.05) percent bone ash as compared to PC fed pigs. Results suggest that pigs fed diets low in P and Ca supplemented with corn-derived phytase performed similar to pigs fed a commercial available phytase and a diet with adequate levels of Ca and P.

Table 1. Effect of corn-expressed phytase on overall growth performance and bone ash in nursery pigs
	Adequate Minerals	Reduced Minerals (NC)	NC + GraINzyme			NC + HiPhos		P - Value
FYT/kg			500	1000	1500	500	SEM	Treatment	Linear	Quadratic
End BW, kg	22.61	21.43	22.87	23.00	23.56	22.49	0.67	0.18	0.01	0.44
ADG, kg/d	0.455	0.421	0.463	0.465	0.483	0.453	0.015	0.10	0.01	0.42
G:F	0.644	0.630	0.638	0.666	0.679	0.663	0.019	0.41	0.04	0.90
Bone Ash, g	1.122d	0.840a	0.984bc	1.037c	1.098cd	0.951b	0.029	<0.01	0.09	0.35
Bone Ash, %	26.01e	21.61a	24.07c	25.45de	25.09d	23.08b	0.284	<0.01	<0.01	<0.01

^a.b.c.d.e. Means with different superscripts are significantly different (P < 0.05).