Efficacy of natural alternatives to antibiotic on the growth performance, gut microbial population, intestinal morphology, and serum biochemical metabolites of broiler chickens

Figures & data

Table 1. Ingredients and nutrient levels of the basal diets.

Ingredients, %	Stater period (d 1–10)	Grower period (d 11–24)	Finisher period (d 25–35)
Corn	53.88	57.33	62.20
Soybean meal	40.78	36.98	31.82
Soybean oil	1.10	1.84	2.41
Limestone	0.87	0.81	0.75
Dicalcium phosphate	1.84	1.64	1.47
Salt	0.38	0.38	0.38
Vitamin premix^a	0.25	0.25	0.25
Mineral premix^b	0.25	0.25	0.25
DL-methionine	0.35	0.31	0.28
L-lysine HCL	0.22	0.16	0.16
L-threonine	0.08	0.05	0.03
Total	100	100	100
Calculated composition
AME, kcal/kg	2800	2900	3000
Crude protein, %	21.47	20.11	18.28
Lys, %	1.36	1.22	1.10
Met, %	0.66	0.60	0.55
Met + Cys, %	1.00	0.93	0.86
Thr, %	0.90	0.82	0.73
Ca, %	0.89	0.82	0.75
Available P, %	0.40	0.36	0.33
Na, %	0.16	0.15	0.15
Cl, %	0.29	0.29	0.29

^aVitamin premix provided the following per kilogram of diet: vitamin A, 11,500 U; cholecalciferol, 2,100 U; vitamin E, 22 U; vitamin K3, 1.50 mg; thiamine, 3 mg; riboflavin, 4.4 mg; pantothenic acid, 25 mg; niacin, 40 mg; choline chloride, 560 mg; biotin, 0.1 mg; folic acid, 0.8 mg; pyridoxine 10 mg; vitamin B12, 0.060 mg.

^bTrace mineral premix provided the following in milligrams per kilogram of diet: iron, 50 mg; zinc, 55 mg; manganese, 75 mg; iodine, 1.8 mg; copper, 8 mg; selenium, 0.3 mg; cobalt, 0.2 mg.

Table 2. Effect of the experimental diets on growth performance of broiler chickens^d.

	Treatment^e
Item	CON	AGP	EO	MCFA	SYN	EOW	SEM	p-Value
Starter (day 1–10)
Body weight gain, g	209.16	260.10	253.13	247.40	255.23	247.33	5.01	.12
Feed intake, g	232.67	270.00	250.00	259.00	272.00	260.00	5.06	.30
Feed conversation ratio	1.11	1.04	0.99	1.04	1.06	1.05	0.01	.14
Grower (day 11–24)
Body weight gain, g	926.17	956.67	928.67	918.20	832.10	843.13	14.12	.10
Feed intake, g	1330.00^a	1325.00^a	1333.33^a	1273.33^ab	1182.00^b	1190.00^b	16.00	.04
Feed conversation ratio	1.43	1.38	1.43	1.38	1.44	1.41	0.01	.59
Finisher (day 25–35)
Body weight gain, g	841.33	946.33	823.67	905.67	931.67	977.00	19.42	.23
Feed intake, g	1623.70	1773.30	1686.70	1739.70	1800.00	1813.33	32.32	.54
Feed conversation ratio	1.93	1.88	2.05	1.92	1.93	1.86	0.02	.22
Overall (day 1–35)
Body weight gain, g	1976.67^c	2163.10^a	2005.47^bc	2071.27^b	2010.00^bc	2067.47^b	10.84	.004
Feed intake, g	3186.33	3368.33	3272.00	3270.00	3254.00	3263.33	25.86	.54
Feed conversation ratio	1.61^ab	1.55^c	1.63^a	1.58^bc	1.62^ab	1.58^bc	0.005	.02

^a–cMeans with different superscripts in each row are significantly different (p < .05).

^dData are means of 6 replicate pens with 15 birds per pen.

^eCON: basal diet without feed additive; AGP: basal diet + antibiotic growth promoter; EO: basal diet + essential oils; MCFA: basal diet + medium-chain fatty acids; SYN: basal diet + symbiotic; EOW: drinking water + essential oils.

Table 3. Effect of the experimental diets on carcass characteristics of broiler chickens.

	Treatment^c
Item	CON	AGP	EO	MCFA	SYN	EOW	SEM	p-Value
Carcass	64.95	64.07	65.82	64.14	67.38	65.26	0.42	.25
Breast	23.50	24.03	24.22	24.51	25.07	24.05	0.27	.69
Thigh	19.75	18.89	19.58	19.05	20.22	19.62	0.17	.29
Liver	2.15	2.17	2.02	2.18	2.28	2.23	0.057	.87
Spleen	0.09^b	0.08^b	0.09^b	0.13^a	0.09^b	0.08^b	0.01	.01
Bursa of fabricius	0.10	0.08	0.09	0.10	0.11	0.07	0.01	.43

^a,bMeans with different superscripts in each row are significantly different (p < .05).

^cCON: basal diet without feed additive; AGP: basal diet + antibiotic growth promoter; EO: basal diet + essential oils; MCFA: basal diet + medium-chain fatty acids; SYN: basal diet + symbiotic; EOW: drinking water + essential oils.

Table 4. Effect of the experimental diets on cecalmicroflora population (log₁₀cfu/g) of broiler chickens.

	Treatment^d
Item	CON	AGP	EO	MCFA	SYN	EOW	SEM	p-Value
Total anaerobic bacteria	9.23^a	9.10^b	9.23^a	9.14^ab	9.23^a	9.19^a	0.01	.02
Lactic acid bacteria	7.94^ab	7.84^c	7.96^ab	7.99^a	7.96^ab	7.86^bc	0.01	.02
Coliforms	8.32^a	8.15^c	8.23^b	8.18^bc	8.25^b	8.25^b	0.01	.002
Clostridium perfringens	6.00^a	5.78^bc	5.88^ab	5.72^c	5.84^bc	5.89^ab	0.02	.01

^a–cMeans with different superscripts in each row are significantly different (p<.05).

^dCON: basal diet without feed additive; AGP: basal diet + antibiotic growth promoter; EO: basal diet + essential oils; MCFA: basal diet + medium-chain fatty acids; SYN: basal diet + symbiotic; EOW: drinking water + essential oils.

Table 5. Effect of the experimental diets on intestinal morphology (mm) of broiler chickens.

	Treatment^d
Item	CON	AGP	EO	MCFA	SYN	EOW	SEM	p-Value
Duodenum
Villus height	1370.17	1304.67	1339.67	1277.67	1333.33	1276.50	13.11	.27
Crypt depth	255.50	232.00	239.50	236.67	231.83	266.67	6.29	.52
Villuswidth	184.83	186.00	175.00	189.50	192.50	175.00	2.58	.27
Jejunum
Villus height	1204.17^c	1364.50^ab	1279.83^bc	1461.00^a	1247.33^bc	1264.33^bc	19.50	.008
Crypt depth	266.50	264.83	261.17	250.17	265.67	246.83	8.46	.97
Villuswidth	208.33	186.00	192.00	219.17	200.33	206.33	5.85	.63
Ileum
Villus height	1016.33	993.17	1015.83	1054.00	918.83	1062.33	26.88	.69
Crypt depth	172.83	184.67	181.33	168.50	194.83	171.33	5.90	.79
Villuswidth	208.83	213.00	203.17	171.33	169.00	208.50	7.80	.38

^a–cMeans with different superscripts in each row are significantly different (p < .05).

^dCON: basal diet without feed additive; AGP: basal diet + antibiotic growth promoter; EO: basal diet + essential oils; MCFA: basal diet + medium-chain fatty acids; SYN: basal diet + symbiotic; EOW: drinking water + essential oils.

Table 6. Effect of the experimental diets on serum biochemical parameters of broiler chickens.

	Treatment^d
Item	CON	AGP	EO	MCFA	SYN	EOW	SEM	p-value
Cholesterol, mg/dL	146.16^a	142.33^a	142.66^a	109.00^b	134.33^a	142.32^a	2.06	.001
Triglycerides, mg/dL	105.50	102.83	98.66	103.33	97.83	103.33	1.84	.81
HDL-C^e, mg/dL	71.83	71.66	73.83	73.66	78.00	66.33	1.57	.42
VLDL-C^f, mg/dL	21.10	20.56	19.73	20.66	19.56	20.66	0.37	.81
LDL-C^g, mg/dL	53.23^a	50.10^ab	49.43^abc	39.70^bc	36.76^c	55.66^a	1.72	.02
Total protein, ,g/dL	4.67	4.28	4.87	4.53	4.30	4.58	0.76	.24
Albumin, mg/dL	1.41	1.38	1.45	1.34	1.17	1.25	0.04	.26

^a–cMeans with different superscripts in each row are significantly different (p < .05).

^dCON: basal diet without feed additive; AGP: basal diet + antibiotic growth promoter; EO: basal diet + essential oils; MCFA: basal diet + medium-chain fatty acids; SYN: basal diet + symbiotic; EOW: drinking water + essential oils.

^eHDL-C: high density lipoprotein cholesterol.

^fLDL-C: low density lipoprotein cholesterol.

^gVLDL-C: very low density lipoprotein cholesterol.

Data availability statement

All data generated and analysed during this study are included in this published article.