Table 3.

Predicted effect of graded concentrations of phytate P (x) and log doses of phytase (v) on broiler growth performance from hatch to day 21 or 42 and tibia ash, minerals and bone breaking strength (BBS) on day 21.

			Model
Item	Equation	RMSE	Adjusted R2	P-value
Hatch to day 21
Feed intake, g	y = 754.7 + 921.8x − 1,670x2} + 204.2v − 37.05v2	37.5	0.33	<0.0001
Body weight gain, g	y = 409 + 1,369x − 2324x2 + 172.7 − 27.72v2	29.7	0.55	<0.0001
Feed conversion, g:g	y = 1.593 − 1.117x + 1.772x2 − 0.033v	0.02	0.66	<0.0001
Hatch to day 42
Feed intake, g	y = 3,587 + 601.6v − 124.3v2	147	0.03	0.0372
Body weight gain, g	y = 1,706 + 2,559x − 4,570x2 + 384.3v − 72.37v2	98.3	0.27	<0.0001
Feed conversion, g:g	y = 1.855 − 0.888x + 1.767x2 − 0.024v	0.03	0.58	<0.0001
Day 21
Tibia ash weight, g	y = 1.063 − 1.572x + 1.204v − 0.206v2	0.17	0.53	<0.0001
Tibia ash, %	y = 33.32 + 78.79x − 133.3x2 + 1.512v	1.69	0.47	<0.0001
Tibia Ca, %	y = 33.22 + 13.31x − 33.42x2	0.79	0.54	<0.0001
Tibia P, %	y = 32.73 − 118.0x + 199.0x2 − 7.475v + 55.38v2 − 90.92x2v	1.06	0.18	<0.0001
BBS, N	y = 133.6 − 456.7x + 599.1x2 + 6.800v	15.3	0.13	<0.0001