Table 4.

Growth performance of broilers fed with diets with gradient phytase supplementation from 1 to 29 d of age.¹

Item	BW, kg/bird	BW gain, kg/bird	Feed intake, kg/bird	FCR, kg:kg2	Mortality, %3
Dietary treatment
1) Negative control (NC)4	1.617	1.577	2.165	1.372	5.1
2) NC + 500 FTU/kg5	1.645	1.604	2.174	1.356	2.6
3) NC + 1,500 FTU/kg	1.670	1.629	2.210	1.356	1.6
4) NC + 4,500 FTU/kg	1.756	1.715	2.272	1.325	2.9
5) NC + 13,500 FTU/kg	1.737	1.699	2.249	1.325	3.4
6) NC + 40,500 FTU/kg	1.725	1.688	2.234	1.324	2.5
7) Positive control (PC)	1.621	1.583	2.168	1.370	2.2
8) PC + inositol6	1.587	1.548	2.148	1.388	2.1
Pooled standard error	0.019	0.018	0.024	0.010	1.1
Source of variation	-------------------Probabilities--------------------
Log-linear effect of phytase7	<0.001	<0.001	0.003	<0.001	0.06
Log-quadratic effect of phytase7	<0.001	<0.001	0.003	<0.001	0.08
Treatment 1 vs. 7	0.85	0.83	0.92	0.86	0.028
Treatment 6 vs. 8	<0.001	<0.001	0.005	<0.001	0.65
Treatment 7 vs. 8	0.16	0.15	0.50	0.14	0.74

Abbreviation: FCR, feed conversion ratio.

¹Values are least square means of 8 replicate pens, with each pen having 30 birds at placement.

²Feed conversion ratio was corrected for mortality.

³Mortality was arcsine transformed.

⁴The negative control diet was formulated to contain 0.165 and 0.150% lower calcium and phosphorus, respectively, than the positive control diet.

⁵One unit of phytase activity (FTU) is defined as the quantity of enzyme to liberate 1 μmol of inorganic phosphate per minute from 0.0051 mol/L sodium phytate at pH 5.5 and 37°C.

⁶Inositol supplementation was calculated based on the maximum inositol liberation from the diet containing the highest phytase concentration (treatment 6).

⁷Phytase levels were log₁₀ transformed before analysis. Log-linear and log-quadratic effects were analyzed for treatments 1 to 6.