Phytate phosphorus utilization and intestinal phytase activity in laying hens

Figures & data

Table 1 Dietary ingredients and chemical composition of the experimental layer diets.

Diet
	Exp. 1	Exp.2°	Exp. 2°	Exp. 2°
	diet 1	diet 1	diet 2	diet 3
Ingredients
Yellow corn, g/kg	650.9	637.1	634.5	625.4
Soybean meal, g/kg	200.0	206.5	206.0	208.0
Poultry fat, g/kg	38.2	30.0	30.0	33.7
Dicalcium phosphate, g/kg	-	6.0	12.5	19.0
Defluorinated phosphate, g/kg	15.0	-	-	-
Ground limestone, g/kg	82.5	109.4	106.0	102.9
Salt, g/kg	3.5	3.0	3.0	3.0
Vitamin premix#, g/kg	2.5	2.5	2.5	2.5
Trace mineral mix§, g/kg	0.5	0.5	0.5	0.5
DL-Methionine, g/kg	0.8	2.0	2.0	2.0
Lysine-HCL, g/kg	3.0	3.0	3.0	3.0
Calculated analysis
Metabolizable energy, kcal/kg	3000	2892	2882	2887
Total phosphorus, g/kg	5.8	4.3	5.3	6.3
Available phosphorus, g/kg	2.0	3.0	4.0
Calcium, g/kg	36.8	40.0	40.0	40.0
Determined analysis
Total phosphorus, g/kg	7.0	4.5	5.7	7.2

° Nine dietary combinations were fed to the hens in Experiment 2; diets consisted of 3 concentrations of AP (0.2, 0.3, and 0.4%) and each level of P was supplemented with three levels of commercial feed grade phytase enzyme (0, 300, and 600 FTU/kg).

# Vitamin premix provided: Mn, 88 mg; Cu, 6.6 mg; Fe, 8.5 mg; Zn, 88 mg; Se, 0.30 mg; vitamin A, 6600 U; cholecalciferol, 2805 U; vitamin E, 10 U; vitamin K, 2.0 mg per kg diet.

§ Mineral premix provided: riboflavin, 4.4 mg; pantothenic acid, 6.6 mg; niacin 24.2, mg; choline, 110 mg; vitamin B12, 8.8 mg; ethoxyquin, 1.1 mg per kg of diet.

Table 2 Effects of age and strain on phytate phosphorus and phosphorus retentions and phytase activity in laying hens.

Phytate phosphorus retention, %	Phosphorus retention, %	Phytase activity, nmol/mg/min
Age, weeks
32	39.5^a	39.9^a	36.3^a
52	31.3^b	31.5^b	25.9^b
72	36.5^a	44.5^a	30.0^b
SEM	1.18	2.21	1.43
Strain
HB	38.3^a	36.3	32.6
HW	33.2^b	41.1	29.1
SEM	1.06	1.63	1.17
Statistical probabilities
Age	0.001	0.001	0.001
Strain	0.002	ns	ns
Age × strain	ns	0.05	ns

a,b Means within columns followed by different superscripts are significantly different (P<0.05); ns, not significant.

Figure 1 Effect of age on phytate phosphorus retention.

Figure 2 Effect of age on total phosphorus retention.

Table 3 Effects of available phosphorus and exogenous phytase on phytate, total and soluble phosphorus excretion in laying hens.

Available phosphorus, %	Exogenous phytase, FYT/kg	Excreta phytate phosphorus, g/100 g feed	Excreta total phosphorus, g/100 g feed	Excreta soluble phosphorus, mg/g excreta
0.2	0	0.28	0.35	30.4
0.3	300	0.30	0.26	34.1
0.4	600	0.26	0.41	37.1
0.2	0	0.21	0.26	26.9
0.3	300	0.19	0.31	36.7
0.4	600	0.20	0.43	56.9
0.2	0	0.20	0.26	26.9
0.3	300	0.19	0.32	51.4
0.4	600	0.18	0.43	79.5
SEM		0.009	0.02	6.6
Phosphorus
0.2		0.23^a	0.29^c	27.9^c
0.3		0.22^b	0.33^b	40.8^b
0.4		0.21^b	0.42^a	57.8^a
SEM		0.005	0.01	3.8
Phytase
0		0.27^a	0.37^a	33.9^b
300		0.20^b	0.33^b	40.2^b
600		0.19^b	0.34^ab	52.5^a
SEM		0.05	0.01	3.8
Statistical probabilities
Phosphorus		0.02	0.001	0.001
Phytase		0.001	0.05	0.005
Phosphorus × phytase		ns	ns	0.02

a-c Means within columns followed by different superscripts are significantly different (P<0.05);

ns, not significant.

Figure 3 Effect of available phosphorus level on total phosphorus excretion in laying hens.

Figure 4 Effect of exogenous phytase level on total phosphorus excretion in laying hens.

Figure 5 Effect of available phosphorus level on soluble phosphorus excretion in laying hens.