Effects of propolis and stocking density on growth performance, nutrient digestibility, and immune system of heat-stressed broilers

Figures & data

Table 1. Ingredients and calculated and analysed compositions of the basal diets.

Item	Starter (0–21 d)	Finisher (22–42 d)
Ingredients (%)
Corn	50.21	57.43
Soybean meal (48% CP)	36.25	28.20
Wheat gluten	5.00	5.00
Soybean oil	3.94	5.22
Limestone	1.20	1.32
Dicalcium phosphate	1.88	1.33
Salt	0.25	0.25
Choline chloride	0.08	0.08
Sodium bicarbonate	0.05	0.05
l-Lysine	–	0.08
dl-Methionine	0.14	0.04
Vitamin–mineral premix^a	1.00	1.00
Calculated composition
Metabolisable energy (MJ/kg)	12.77	13.40
Crude protein (N × 6.25)	23.00	20.00
Calcium (%)	1.00	0.90
Available phosphorus (%)	0.45	0.35
Lysine (%)	1.13	1.01
Methionine + cystine (%)	0.90	0.72
Threonine (%)	0.86	0.74
Crude fibre	3.45	3.41

^a Permix provided the following per kg of feed: retinol, 2.7 mg; cholecalciferol, 0.05 mg; α-tocopherol, 20 mg; nicotinic acid, 30 mg; cyanocobalamin, 0.12 mg; calcium pantothenate, 10 mg; menadione, 2 mg; thiamine, 1 mg; riboflavin, 4.2 mg; pyridoxine hydrochloride, 1.7 mg; folic acid, 0.5 mg; biotin, 0.5 mg; Fe, 80 mg; Cu, 10 mg; Mn, 100 mg; Zn, 80 mg; Co, 0.2 mg; I, 1.0 mg; Se, 0.3 mg; monensin, 100 mg.

Table 2. Effects of propolis (BG) supplementation and stocking density on growth performance and the coefficient of apparent ileal digestibility (CAID) of nitrogen (N), calcium (Ca) and phosphorus (P), and apparent metabolisable energy (AME), Experiments I and II.

Experiment^a		ADFI, g	ADG, g	FCR	CIAD of N	CIAD of Ca	CIAD of P	AME (MJ/kg)
Exp. I
Basal diet (CON)		85.6^b	51.3^b	1.72	0.651	0.428	0.493	12.20
CON +1 BG g/kg		87.0^b,c	51.5^b	1.68	0.641	0.431	0.490	12.17
CON +2 BG g/kg		86.2^b,c	51.7^b	1.66	0.657	0.426	0.511	12.16
CON +3 BG g/kg		88.4^c	52.4^b,c	1.69	0.647	0.427	0.512	12.16
CON +4 BG g/kg		90.2^c	53.8^c	1.68	0.641	0.412	0.516	12.08
CON +5 BG g/kg		85.8^b	51.8^b	1.65	0.655	0.428	0.505	12.12
Pooled SEM		1.1	0.2	0.02	0.005	0.004	0.007	0.07
p value		0.043	<.001	0.687	0.206	0.081	0.064	0.613
Orthogonal polynomial
Linear		0.005	0.007	0.284	0.424	0.0133	0.004	0.12
Quadratic		0.358	0.017	0.278	0.411	0.0968	0.800	0.58
Exp. II
Stocking density	BG (g/kg)
LSD	0	77.7	44.3	1.75	0.522	0.437	0.488	11.03
LSD	4	80.4	46.5	1.73	0.617	0.426	0.503	12.29
MSD	0	77.2	43.2	1.79	0.519	0.442	0.482	11.17
MSD	4	78.2	44.5	1.76	0.624	0.429	0.489	12.27
Pooled SEM		0.6	0.1	0.01	0.006	0.009	0.008	0.07
Stocking density
LSD		79.0^c	45.4^c	1.74	0.570	0.432	0.496	11.66
MSD		77.7^b	43.9^b	1.78	0.572	0.436	0.486	11.72
BG
−		77.5^b	43.8^b	1.77	0.521^b	0.440	0.485	11.10^b
+		79.3^c	45.5^c	1.75	0.620^c	0.428	0.496	12.28^c
p value
Stocking density		0.014	0.037	0.185	0.347	0.172	0.118	0.616
BG		0.011	0.029	0.125	<0.001	0.263	0.264	<0.001
Stocking density × BG		0.170	0.342	0.354	0.284	0.429	0.312	0.395

^a,b Means in the same column without the same superscript differ significantly (p<.05).

^c From Day 22 to 42, birds were either raised in a thermoneutral zone (22 °C, Exp. I) or subjected to cyclic heat stress by exposing them to 33 ± 1 °C for 10 h (from 08.00 to 18.00) and 22 °C from 18.00 to 08.00 (Exp. II).

ADFI: average daily feed intake; ADG: average daily gain; FCR: feed conversion ratio; LSD: low stocking density (10 birds/m²), MSD: medium stocking density (14 birds/m²).

Table 3. Effects of propolis (BG) supplementation and stocking density on gut morphology of broilers, Experiments I and II.

		Relative weight (% of BW)				Jejunum morphology (µm)
Experiment^a		Crop	Gizzard	Liver	Small intestine	VH	CD	VH/CD
Exp. I
Basal diet (CON)		0.325	1.399	1.908	1.546	817^b,c	214	3.80^b
CON +1 BG g/kg		0.317	1.396	1.906	1.624	821^b,c	215	3.83^b
CON +2 BG g/kg		0.315	1.411	1.904	1.580	814^c	213	3.84^b
CON +3 BG g/kg		0.322	1.384	1.893	1.537	828^b	215	3.85^b
CON +4 BG g/kg		0.311	1.362	1.862	1.513	861^d	209	4.11^d
CON +5 BG g/kg		0.324	1.417	1.905	1.582	855^d	211	4.06^d
Pooled SEM		0.004	0.015	0.017	0.016	3.1	1.6	0.03
p value		0.068	0.132	0.366	0.667	<.001	0.059	<.001
Orthogonal polynomial
Linear		0.069	0.077	0.052	0.172	<0.001	0.073	<0.001
Quadratic		0.791	0.153	0.299	0.246	<0.001	0.119	<0.001
Exp. II
Stocking density	BG (g/kg)
LSD	0	0.373	1.414	1.879	1.592	745	228	3.27
LSD	4	0.350	1.385	1.904	1.557	739	226	3.27
MSD	0	0.348	1.444	1.893	1.589	728	227	3.20
MSD	4	0.366	1.415	1.887	1.581	730	229	3.19
Pooled SEM		0.057	0.018	0.012	0.016	3.2	3.8	0.06
Stocking density
LSD		0.362	1.400	1.892	1.574	742^d	227	3.27
MSD		0.357	1.430	1.890	1.585	729^b	228	3.19
BG
–		0.361	1.430	1.886	1.590	736	227	3.24
+		0.358	1.400	1.896	1.569	734	228	3.23
p value
Stocking density		0.132	0.177	0.347	0.264	<0.001	0.732	0.629
BG		0.175	0.129	0.238	0.116	0.347	0.641	0.433
Stocking density × BG		0.329	0.274	0.172	0.263	0.433	0.324	0.527

^a–c Means in the same column without the same superscript differ significantly (p<.05).

^d From Day 22–42, birds were either raised in a thermoneutral zone (22 °C, Exp. I) or subjected to cyclic heat stress by exposing them to 33 ± 1 °C for 10 h (from 08.00 to 18.00) and 22 °C from 18.00 to 08.00 (Exp. II).

VH: villus height; CD: crypt depth; VH/CD: villus height to crypt depth ratio; LSD: low stocking density (10 birds/m²); MSD: medium stocking density (14 birds/m²).

Table 4. Effects of propolis (BG) supplementation on blood parameters and plasma immunoglobulin, Experiment I.

	Lipid blood parameters (mg/dL)				Plasma immunoglobulin (log2)
Treatments	TG	Tch	LDL	HDL	IgG	IgM
Basal diet (CON)	98.3^a,b	184^a	74.5^a	92.9	4.03	0.99^b
CON +1 BG g/kg	99.8^a	186^a	75.2^a	93.3	4.07	1.03^b
CON +2 BG g/kg	97.0^a,b	182^a,b	72.7^a	91.7	4.17	1.01^b
CON +3 BG g/kg	101.3^a	186^a	76.4^a	92.7	4.08	1.04^b
CON +4 BG g/kg	95.0^a,b,c	174^b,c	67.3^b	88.9	4.09	1.16^a
CON +5 BG g/kg	91.1^c	170^c	62.0^b	89.3	4.13	1.15^a
Pooled SEM	1.2	1.8	1.3	1.1	0.03	0.04
p value	<.001	<.001	<.001	0.069	0.083	0.021
Orthogonal polynomial
Linear	0.154	0.002	0.003	0.057	0.263	0.012
Quadratic	0.048	0.006	0.009	0.172	0.050	0.171

^a–c Means in the same column without the same superscript differ significantly (p < .05).

TG: triglycerides; Tch: total cholesterol; LDL: low-density lipoprotein; HDL: high-density lipoprotein.

Table 5. Effects of propolis (BG) supplementation and stocking density on blood heterophil (H) and lymphocyte (L) concentrations, H:L ratio and immunity status, Experiment II.^a

					Plasma immunoglobulins (ng/mL)
Treatments		Heterophils (×10^9/L)	Lymphocytes (×10^9/L)	H:L	IgG	IgM
Stocking density	BG (g/kg)
LSD	0	41.2	99.6	0.41^b	936.84	24.14
LSD	4	44.8	100.7	0.45^c	968.54	25.37
MSD	0	39.2	101.4	0.38^d	944.09	25.79
MSD	4	42.1	101.3	0.41^b	978.74	25.88
Pooled SEM		1.8	1.9	0.02	4.31	0.56
Stocking density
LSD		43.0	100.2	0.43	952.69^b	24.76
MSD		40.7	101.4	0.40	961.47^c	25.83
BG
–		40.2	100.5	0.40	940.46^b	24.97
+		43.5	101.0	0.43	973.64^c	25.63
p value
Stocking density		0.092	0.463	<0.001	<0.001	0.135
BG		0.106	0.311	<0.001	<0.001	0.285
Stocking density × BG		0.247	0.752	<0.001	0.064	0.344

^a From Day 22 to 42, birds were subjected to cyclic heat stress by exposing them to 33 ± 1 °C for 10 h (from 08.00 to 18.00) and 22 °C from 18.00 to 08.00.

^b–d Means in the same column without the same superscript differ significantly (p < .05).

LSD: low stocking density (10 birds/m²); MSD: medium stocking density (14 birds/m²).