Evaluating the Effect of Superdosing Natuphos E 5,000 G Phytase on Nursery Pig Performance

A total of 360 pigs (DNA 200×400, initially 5.9 kg) were used in a 42-d growth trial to determine the effect of superdosing a novel phytase source (Natuphos E 5000 G, BASF Corporation, Florham Park, NJ) on nursery pig growth and bone ash. Pigs were randomly allotted to pens at weaning in a randomized complete block design and pens were allotted to 1 of 8 dietary treatments. There were 5 pigs per pen and 9 pens per treatment. Diets were fed in 3 phases (d 0-7, 7-21, and 21-42) with formulated total Ca:P of 1.07, 1.05, and 0.93, respectively. Treatments included a negative control (NC) with 0.40, 0.30, or 0.25% aP from monocalcium P for Phases 1, 2, and 3 respectively; and NC with either 500, 1,000, 2,000, 3,000, or 4,000 FTU/kg phytase. There was also a positive control (PC) with 0.55, 0.45, or 0.40% aP from monocalcium P for Phases 1, 2, and 3 respectively, or PC with 2,000 FTU/kg phytase. On d 42, one pig/pen was euthanized and right fibula removed for bone ash analysis. From d 0 to 42, pigs fed increasing phytase in NC tended to have increased (quadratic, P=0.064) ADG and (linear, P=0.082) ending BW and had improved (quadratic, P=0.008) G:F. Adding 2,000 FTU/kg phytase to PC did not influence ADG or ADFI, but tended to improve (P=0.060) G:F. Additionally, percentage bone ash increased as phytase increased in NC (linear, P<0.001) and PC diets (P<0.001). The NC diet with 500 FTU/kg and PC (no added phytase) were formulated to be equivalent in available Ca and P. When comparing the two diets, pigs fed PC had increased (P=0.007) ADFI and tended to have greater (P=0.099) percentage bone ash; however, pigs fed NC+500 FTU/kg phytase had improved (P=0.032) G:F. In summary, increasing dietary phytase in NC linearly increased percentage bone ash while G:F was maximized at 1,000 FTU/kg. Adding phytase to PC with P and Ca formulated at NRC (2012) recommendations tended to improve feed efficiency.

	Negative control							Positive control
Item	0	500	1,000	2,000	3,000	4,000		0	2,000	SEM
d 0 to 42
ADG, g	369	380	396	387	395	381		400	398	10.2
ADFI, g	540	529	562	551	559	555		580	561	13.5
G:F, g/kg	684	713	705	702	707	686		689	709	7.8
Bone ash, %	44.2	45.2	47.1	48.0	48.4	49.1		47.0	51.3	0.77