Effect of increasing dose level of a novel consensus bacterial 6-phytase variant on phytate degradation in broilers fed diets containing varied phytate levels

Figures & data

Table 1. Ingredient and calculated nutrient content (g/kg, as fed basis) of the basal negative control diets, by phase¹

	Starter (d 0 to 10)			Grower (d 11 to 21)
Ingredient composition, g/kg	Low PP^2 (2.45 g/kg)	Med PP (2.95 g/kg)	High PP (3.45 g/kg)	Low PP (2.45 g/kg)	Med PP (2.95 g/kg)	High PP (3.45 g/kg)
Wheat	450	450	450	500	500	489
Soybean meal	293	275	267	281	237	230
Corn	100	100	100	100	100	100
Broken rice	96.6	50.5	14.9	50.2	26.6	0.00
Canola meal	-	30.0	40.0	-	30.0	40.0
Rice bran	-	34.6	70.3	-	40.3	76.8
Celite	20.0	20.0	20.0	20.0	20.0	20.0
Limestone	13.3	13.0	12.9	12.0	11.7	11.5
Vegetable oil	8.8	9.5	7.8	23.1	20.4	19.0
Dicalcium phosphate	7.7	7.5	7.3	4.8	4.7	4.6
DL-methionine	2.7	2.5	2.5	2.3	2.3	2.2
L-lysine HCL	2.3	2.1	2.0	1.5	2.2	2.0
Vitamin-mineral premix^3	2.0	2.0	2.0	2.0	2.0	2.0
Salt	1.5	1.5	1.5	1.8	1.6	1.6
Sodium bicarbonate	0.9	0.7	0.5	0.5	0.6	0.5
L-threonine	0.9	0.8	0.8	0.4	0.7	0.7
Choline chloride	0.6	0.6	0.6	0.5	0.5	0.5
Calculated nutrient composition, g/kg
AME (kcal/kg)	2,860	2,860	2,860	2,970	2,970	2,970
Net energy (kcal/kg)	2,244	2,248	2,251	2,345	2,352	2,355
DM	905	905	905	906	906	905
Crude protein	215	219	221	211	206	208
Crude fat	26.2	34.0	38.9	41.0	46.0	51.2
Crude fibre	25.9	29.0	30.4	26.4	28.60	29.8
Ash	55.1	59.0	62.8	50.6	53.8	57.6
Total P	4.84	5.43	5.95	4.33	4.93	5.45
Phytate P	2.45	2.95	3.45	2.45	2.95	3.45
Available P	2.77	2.77	2.77	2.25	2.25	2.25
Digestible P	2.60	2.60	2.60	2.10	2.10	2.10
Ca	7.60	7.60	7.60	6.40	6.40	6.40
Na	1.20	1.20	1.20	1.22	1.22	1.22
Chlorine	1.90	1.90	1.90	1.90	1.90	1.90
Potassium	7.80	7.98	8.27	7.73	7.50	7.78
Digestible lysine	11.4	11.4	11.4	10.5	10.5	10.5
Digestible methionine	5.38	5.27	5.21	4.91	4.88	4.83
Digestible methionine & cysteine	8.35	8.35	8.35	7.90	7.90	7.90
Digestible threonine	7.28	7.28	7.28	6.75	6.75	6.75
Digestible isoleucine	7.74	7.74	7.74	7.59	7.17	7.17
Digestible leucine	14.0	13.8	13.5	13.8	12.8	12.6
Digestible tryptophan	2.35	2.32	2.28	2.30	2.14	2.10
Digestible arginine	12.7	12.5	12.2	12.3	11.4	11.2
Digestible histamine	4.86	4.81	4.74	4.76	4.44	4.37
Digestible valine	8.69	8.60	8.46	8.53	8.01	7.87
DEB^4 (meq/kg)	198	202	210	197	191	198

¹Phytase was added on top of the control diets.

²PP, phytate phosphorus.

³Supplied per kg of diet: retinol, 12 000 IU; cholecalciferol, 5000 IU; tocopheryl acetate, 75 mg; menadione, 3.5 mg; thiamine, 3 mg; riboflavin, 9 mg; niacin, 55 mg; pantothenate, 18 mg; pyridoxine, 5 mg; folate, 2 mg; cyanocobalamin, 25 μg; biotin, 200 μg; cereal-based carrier, 149 mg; mineral oil, 2.5 mg; Cu (sulphate), 16 mg; Fe (sulphate), 40 mg; I (iodide), 1.25 mg; Se (selenate), 0.3 mg; Mn (sulphate and oxide), 80 mg; Zn (sulphate and oxide), 100 mg.

⁴DEB, dietary electrolyte balance = Na+K-Cl.

Table 2. Analysed nutrient content and phytase activities of the treatment diets, by phase

	Starter (d 0 to 10)			Grower (d 11 to 21)
Nutrient content, g/kg as is	Low PP^1 (2.45 g/kg)	Med PP (2.95 g/kg)	High PP (3.45 g/kg)	Low PP (2.45 g/kg)	Med PP (2.95 g/kg)	High PP (3.45 g/kg)
CP	217	222	231	208	209	213
Total P	5.13	5.66	6.13	4.80	5.16	5.49
Phytate P	2.96	3.49	3.98	2.98	3.45	3.89
Total Ca	7.74	8.16	7.82	7.08	7.02	6.63
Phytase activity, FTU/kg
BD^2	347	334	379	355	344	416
BD + PhyG at 500 FTU/kg	770	805	917	844	958	828
BD + PhyG at 1,000 FTU/kg	1,257	1,265	1,443	1,396	1,646	1,245
BD + PhyG at 2,000 FTU/kg	1,937	1,919	2,199	2,547	2,521	2,312
BD + PhyG at 4,000 FTU/kg	4,502	4,241	3,788	4,407	4,327	4,820

¹PP, phytate phosphorus. ²BD, basal diet at 0 FTU/kg phytase, as detailed in Table 1.

Table 3. Apparent ileal digestibility (AID) of IP₆, sum IP_3-6 and P at 21 d of age¹

	Dietary phytate P level	PhyG dose level (FTU/kg)	AID IP6, %	AID sum of IP3-6, %	AID P, %
Treatment means
	Low	0	31.2	19.0	47^ef
	Low	500	74.5	65.3	61^bcd
	Low	1,000	88.1	81.6	70^abc
	Low	2,000	97.2	94.7	73^ab
	Low	4,000	100.0	96.8	79^a
	Med	0	25.2	13.1	43^fg
	Med	500	69.4	55.2	57^cdef
	Med	1,000	83.0	73.2	70^abc
	Med	2,000	92.7	87.3	72^ab
	Med	4,000	97.2	93.0	72^ab
	High	0	18.8	6.9	33^g
	High	500	65.9	52.5	56^def
	High	1,000	71.4	59.7	58^cde
	High	2,000	92.6	87.4	75^a
	High	4,000	97.1	93.9	81^a
SEM			3.5	4.8	3.0
Main effect means
Dietary phytate level	Low		78.2^a	71.5^a	66.0
	Med		73.5^ab	64.4^ab	63.0
	High		69.2^b	60.1^b	60.0
SEM			1.56	2.15	1.00
Phytase dose level		0	25.1^d	13.0^d	41.0
		500	70.0^c	57.7^c	58.0
		1,000	80.8^b	71.5^b	66.0
		2,000	94.2^a	89.8^a	73.0
		4,000	98.1^a	94.5^a	77.0
SEM			2.01	2.77	2.00
P – value, dietary phytate level			0.001	0.002	0.008
P – value, phytase dose level			<0.001	<0.001	<0.001
P – value, phytate level x phytase dose-level			0.61	0.70	0.003
P – value, ‘linear’ dietary phytate level			0.16	0.16	0.15
P – value, ‘exponential’, phytase dose level^2			<0.001	<0.001	<0.001

¹The factorial analysis was a 3 × 5 factorial ANOVA (3-way ANOVA) with 3 dietary phytate levels and 5 phytase dose levels.

²The exponential equation is: Y = a + b*e^{(c*analysed phytase dose).}

^a,b,c,d,e,f,For the comparison of treatment means (when a significant interaction was identified), or the main effect of dietary phytate level or phytase dose-level, means in the same column with no common superscripts are significantly different at P < 0.05.

Table 4. Ileal content (g/100 g DM) of individual IP_3-6 esters at 21 days of age¹

	Dietary phytate-P level	PhyG dose level (FTU/kg)	IP6-P	IP5-P	IP4-P	IP3-P
Treatment means
	Low	0	0.69	0.08	0.03	0.009
	Low	500	0.26	0.06	0.03	0.005
	Low	1,000	0.12	0.03	0.03	0.009
	Low	2,000	0.03	0.01	0.01	0.005
	Low	4,000	0.00	0.01	0.01	0.007
	Med	0	0.77	0.09	0.03	0.007
	Med	500	0.33	0.08	0.06	0.014
	Med	1,000	0.19	0.05	0.05	0.012
	Med	2,000	0.08	0.02	0.03	0.008
	Med	4,000	0.03	0.01	0.02	0.013
	High	0	0.91	0.10	0.03	0.009
	High	500	0.38	0.09	0.05	0.013
	High	1,000	0.31	0.07	0.04	0.015
	High	2,000	0.08	0.03	0.02	0.009
	High	4,000	0.03	0.02	0.01	0.008
SEM			0.04	0.01	0.01	0.004
Main effect means
Dietary phytate level	Low		0.22^b	0.04^ab	0.02^b	0.01
	Med		0.28^b	0.05^bab	0.03^a	0.01
	High		0.34^a	0.06^a	0.03^ab	0.01
SEM			0.018	0.004	0.004	0.002
Phytase dose level		0	0.79^a	0.09^a	0.03^abc	0.01
		500	0.32^b	0.08^a	0.04^a	0.01
		1,000	0.21^c	0.05^b	0.04^ab	0.01
		2,000	0.06^d	0.02^c	0.02^bc	0.01
		4,000	0.02^d	0.01^c	0.01^c	0.01
SEM			0.024	0.005	0.005	0.002
P – value, dietary phytate level			<0.001	0.002	0.052	0.201
P – value, phytase dose level			<0.001	<0.001	<0.001	0.635
P – value, phytate level x phytase dose-level			0.370	0.570	0.950	0.840
P – value, ‘linear’ dietary phytate level			0.169	0.046	0.184	0.109
P – value, ‘exponential’, phytase dose level			<0.001	<0.001	0.531	0.846

¹The factorial analysis was a 3 × 5 factorial ANOVA (3-way ANOVA) with 3 dietary phytate levels and 5 phytase dose levels. ^a,b,c,d For the comparison of treatment means (when a significant interaction was identified), or the main effect of dietary phytate level or phytase dose-level, means in the same column with no common superscripts are significantly different at P < 0.05.

Figure 1. Fitted exponential curves for the relationships between ileal IP₆–P (a), IP₅–P (b) and IP₄–P (c) content (g/100 g of digesta freeze-dried DM) and the analysed phytase dose level in diets of varying phytate-P level, measured at 21 days of age¹.

Table 5. Calculated dietary content (g/kg diet) of ileal digestible P and sum of IP_{3-6 –} P at 21 d of age¹

	Dietary phytate-P level	PhyG dose level (FTU/kg)	Ileal dig P	Ileal dig IP3-6–P	ileal dig IP3-6–P as a % of total dig P
Treatment means
	Low	0	2.26^fg	0.57^e	25.0
	Low	500	2.94^ef	1.95^d	66.2
	Low	1,000	3.36^cde	2.43 ^cd	72.4
	Low	2,000	3.5^bcde	2.82^abcd	80.6
	Low	4,000	3.81^abc	2.88^abc	75.7
	Med	0	2.24^fg	0.46^e	20.4
	Med	500	2.93^ef	1.93^d	65.8
	Med	1,000	3.61^bcde	2.55^bcd	70.8
	Med	2,000	3.7^bcd	3.05^abc	82.4
	Med	4,000	3.71^bcd	3.24^ab	87.5
	High	0	1.8^g	0.27^e	14.9
	High	500	3.05^de	2.02^d	66.2
	High	1,000	3.18^cde	2.30^cd	72.3
	High	2,000	4.11^ab	3.36^ab	81.9
	High	4,000	4.46^a	3.62^a	81.1
SEM			0.151	0.17
Main effect means
Dietary phytate level	Low		3.17^b	2.13^a
	Med		3.18^b	2.25^a
	High		3.36^a	2.31^a
SEM			0.061	0.076
Phytase dose level		0	2.02^d	0.43^d
		500	2.97^c	1.96^c
		1,000	3.38^b	2.43^b
		2,000	3.77^a	3.08^a
		4,000	3.99^a	3.25^a
SEM			0.087	0.098
P – value, dietary phytate level			0.055	0.246
P – value, phytase dose level			<0.001	<0.001
P – value, phytate level x phytase dose-level			0.002	0.08
P – value, ‘linear’ dietary phytate level			0.470	0.440
P – value, ‘exponential’, phytase dose level			<0.001	<0.001

¹The factorial analysis was a 3 × 5 factorial ANOVA with 3 dietary phytate levels and 5 phytase dose levels.

^a,b,c,dFor the comparison of treatment means (when a significant interaction was identified), or the main effect of dietary phytate level or phytase dose-level, means in the same column with no common superscripts are significantly different at P < 0.05.

Figure 2. Calculated increase (above NC) in ileal digestible IP_3-6–P content (g/kg feed) of diets with low, medium or high dietary phytate-P content and phytase added at different dose levels, determined in broilers at 21 d of age.