Varying starch to fat ratios in pelleted diets: I. Effects on nutrient digestibility and production performance in Eimeria–challenged broiler chickens

Figures & data

Table 1. Experimental diet composition, calculated and analysed nutrient content (g/kg as fed)

Ingredients	HS*	LS*
Wheat	412.6	412.6
Fish meal (72% CP)	100	100
Soybean meal (47.3% CP)	185	185
Wheat starch^1	250	-
Rapeseed oil	-	87.4
Sand^2	-	162.6
L-Lysine	2.8	2.8
DL-Methionine	2.8	2.8
L-Threonine	2	2
Limestone	12	12
Monocalcium phosphate	15	15
Sodium chloride	3	3
Titanium dioxide	5	5
Choline chloride	2	2
Mineral & Vitamin premix^3	6.3	6.3
Enzyme (Rovabio)^4	1.5	1.5
Calculated nutrient content
Metabolisable energy (MJ/kg)	12.13	12.13
Dig. Lysine	12.9	12.9
Dig. Methionine	6.1	6.1
Dig Threonine	8.6	8.6
Analysed nutrient content
Gross energy (MJ/kg)	16.20	15.95
DM (g/kg)	908	913
Starch (g/kg)	448	231
Fat (g/kg)	14.2	95.4
Crude Protein (g/kg)	211	211
Calcium (g/kg)	13.7	13.3
Phosphorous (g/kg)	8.1	7.9
Starch gelatinisation, g/kg starch	574.9	152.4
Starch: fat ratio	31.5: 1	2.4: 1

* HS and LS: high and low starch to fat ratio.

¹ Wheat starch, low gluten (produced by Roquette Amilina AB, provided by Alimenta AS, Hagan, Norway): Dry matter, 87%; Starch, 86%; Protein (Nx6.25), 0.35% max; Lipids, 0.1% max; Cellulose, 0.1% max and particle size distribution as follows: >200 µm, 2% max; >10 µm, 75% min.

²High purity quartz sand, NC4AF (The Quartz Corp, Drag, Norway): SiO₂ > 99.9%; particle size distribution as follows: >150 µm <5%; 75–150 µm >75%; <75 µm <15%.

³Mineral and vitamin premix provided the following per kg diet: Fe, 53 mg; Mn, 125 mg; Zn, 83 mg; Cu, 15 mg; I, 0 · 75 mg; Se, 0 · 30 mg; retinyl acetate, 5.75 mg; cholecalciferol, 0.18 mg; dl-α-tocopheryl acetate, 80 mg; menadione, 10 mg; thiamine, 6 mg; riboflavin, 26 mg; niacin, 35 mg; calcium pantothenate, 26 mg; pyridoxine, 15 mg; cobalamin, 0.04 mg; biotin, 0.6 mg; folic acid, 5 mg.

⁴Enzyme Rovabio Excel AP T-Flex (Adisseo, Antony, France) provided the following per kg diet: Endo-1,4-β-xylanase: 33 000 visco units; Endo-1,3(4)-β-glucanase: 45 000 visco units; Endo-1,4-β-glucanase (cellulase) >9600 DNS units + 16 other enzyme activities obtained from a fermentation broth of Penicillium funiculosum.

Table 2. Effect of varying ratios of starch to fat on the overall production performance of broilers.¹

	10–15 days			15–24 days			24–28 days			10–28 days
Diets	FI^3	BWG^3	FCR^3	FI	BWG	FCR	FI	BWG	FCR	FI	BWG	FCR
HS^2	392	267	1.476	931	729	1.277	610	424	1.440	1893	1419	1.334
	± 12.0	± 8.3	± 0.04	± 15.2	± 8.3	± 0.01	± 4.9	± 5.8	± 0.02	± 28.5	± 20.1	± 0.00
LS^2	411	272	1.516	948	696	1.364	651	433	1.503	1968	1400	1.406
	± 4.1	± 3.8	± 0.02	± 12.0	± 11.9	± 0.01	± 4.8	± 4.5	± 0.01	± 16.9	± 12.8	± 0.01
P-value*	0.149	0.977	0.184	0.488	0.033	<0.001	<0.001	0.371	0.003	0.021	0.106	<0.001

¹Values are means ± SEM, n = 12 replicate pens of 80 birds each.

²HS and LS: high and low starch to fat ratio.

³FI: Feed intake (g/bird); BWG: Body weight gain (g/bird); FCR: Feed conversion ratio: FI/BWG.

* Differences between means are considered significant at P < 0.05.

Table 3. Effect of varying ratios of starch: fat on amylase activity (Unit/g jejunal chyme), nutrient concentration in ileal digesta¹ and ileal digestibility of nutrients¹ and energy

			Freeze-dried ileal digesta		Ileal digestibility coefficients
Age	Diets	Amylase activity^3	Starch (g/kg)	Fat (g/kg)	Starch	Fat	Energy^3
16 days	HS^2	75.9 ± 10.7	80.3 ± 1.38	22.2 ± 0.12	0.950 ± 0.01	0.575 ± 0.03	-
	LS^2	50.7 ± 10.6	58.1 ± 1.33	56.1 ± 0.50	0.893 ± 0.03	0.758 ± 0.02	-
	P-value*	0.1112	0.0665	< 0.001	0.0832	< 0.001	-
29 days	HS	74.3 ± 11.1	42.3 ± 0.46	18.0 ± 0.10	0.978 ± 0.00	0.690 ± 0.01	0.766 ± 0.01
	LS	51.1 ± 7.8	29.2 ± 0.45	29.0 ± 0.20	0.950 ± 0.01	0.878 ± 0.01	0.747 ± 0.01
	P-Value*	0.0831	0.0148	< 0.001	0.0094	< 0.001	0.1076

¹Values are means ± SEM; n = 12 replicate pens of 2 birds each

²HS and LS: high and low starch to fat ratio

³ n = 12 replicate pens of 1 bird each

* Differences between means were considered significant at P < 0.05

Table 4. Relationships between age and the apparent ileal digestibility coefficients ¹ of starch and fat in broilers

	HS diet ^2		LS diet ^2
Age	Starch digestibility	Fat digestibility	Starch digestibility	Fat digestibility
16 d	0.950 ± 0.009	0.575 ± 0.028	0.893 ± 0.027	0.758 ± 0.019
29 d	0.978 ± 0.002	0.690 ± 0.015	0.950 ± 0.076	0.878 ± 0.007
P-values*	0.007	0.002	0.145	< 0.001

¹Values are means ± SEM; n = 12 replicate pens of 2 birds each

²HS and LS: high and low starch to fat ratio

* Differences between means were considered significant at P < 0.05