Table 3.

Effects of graded levels of phytase supplementation on serum metabolites concentration in Pekin ducks fed phosphorus-deficient diets.

Item	Positive control (PC)	Negative control (NC) with phytase supplementation (FTU/kg)						SEM	P-value
		0	500	2,500	5,000	7,500	10,000		ANOVA	Linear	Quadratic
Total protein, TP (g/L)
14 D	31.3b	36.3a	36.4a	30.3b	32.6a,b	33.0a,b	33.0a,b	0.40	0.0246	0.0283	0.526
35 D	26.4b,c	31.0a	29.6a,b	27.8ab	22.7c	23.5c	22.8c	1.23	<0.0001	<0.0001	0.220
Albumin, ALB (g/L)
14 D	13.8b	16.5a	17.1a	16.1a	13.5b	12.9b	12.7b	0.51	<0.0001	<0.0001	0.001
35 D	9.58b,c	12.06a	11.69a	11.05a,b	8.54c	8.88c	8.48c	0.55	<0.0001	<0.0001	0.103
Urea (mmol/L)
14 D	0.70b	1.07a	1.00a	0.91a	0.69b	0.63b	0.60b	0.06	<0.0001	<0.0001	0.054
35 D	0.59b	0.96a	0.94a	0.80a	0.57b	0.55b	0.53b	0.06	<0.0001	<0.0001	0.039
Calcium, Ca (mmol/L
14 D	2.13b	2.87a	2.60a	2.61a	2.00b	1.40c	1.92b	0.12	<0.0001	<0.0001	<0.001
35 D	1.68c	2.51a	2.19b	2.11b	1.62c	1.54c	1.60c	0.09	<0.0001	<0.0001	0.108
Phosphorus, P (mmol/L)
14 D	3.36c	4.58b,c	5.40b	6.72a	4.52b,c	3.59c	3.60c	0.44	<0.0001	0.2528	0.002
35 D	2.35c	3.40b,c	4.48a,b	5.44a	2.96b,c	2.31c	2.21c	0.53	0.0002	0.1830	0.001
Alkaline phosphatase, ALP (U/L)
14 D	886c	2,039a	1,956a	1,398b	969c	880c	847c	112.3	<0.0001	<0.0001	0.027
35 D	620c	1,542a	1,379a	975b	583c	534c	507c	89.59	<0.0001	<0.0001	0.059

Data are means of 8 replicates with 1 bird per replicate.

^a–cMeans within column and under each main effect with no common superscript differ significantly (P < 0.05).

Abbreviation: ANOVA, analysis of variance.