Effect of dietary orange and grapefruit peel on growth performance, health status, meat quality and intestinal microflora of broiler chickens

Figures & data

Table 1. Ingredient and nutrient composition of basal diets.

Ingredient, % as fed-basis	Starter (0–14 days)	Grower (15–28 days)	Finisher (29–42 days)
Corn	32.58	35.50	39.34
Flax meal	0.00	4.00	4.00
Wheat	20.00	20.00	20.00
Soy meal	36.17	27.03	20.81
Gluten	2.00	4.00	6.00
Oil	3.85	4.20	4.70
Monocalcium phosphate	1.68	1.54	1.45
Calcium carbonate	1.51	1.40	1.33
Salt	0.39	0.36	0.33
Methionine	0.32	0.29	0.26
Lysine	0.30	0.41	0.48
Choline	0.05	0.05	0.05
Threonine	0.15	0.22	0.25
Premix for broilers*	1.00	1.00	1.00
Total	100.00	100.00	100.00
Calculated analysis, %
Metabolisable energy, kcal/kg	3.039.79	3126.76	3215.78
Dry matter, %	88.52	89.52	88.88
Crude protein, %	23.00	21.50	20.00
Ether extract, %	5.48	6.34	6.86
Crude fibre, %	3.77	3.36	3.14
Calcium, %	0.96	0.87	0.81
Phosphorus, %	0.77	0.69	0.64
Av. phosphorus	0.48	0.44	0.40
Chlorine, %	0.35	0.35	0.34
Lysine, %	1.44	1.29	1.19
Methionine, %	0.69	0.63	0.39
Methionine + cysteine, %	1.08	0.99	0.94
Threonine, %	0.97	0.88	0.94
Tryptophan, %	0.25	0.20	0.17

*1 kg premix contains 1,100,000 IU/kg vit. A; 200,000 IU/kg vit. D3; 2700 IU/kg vit. E; 300 mg/kg vit. K; 200 mg/kg Vit. B1; 400 mg/kg vit. B2; 1485 mg/kg pantothenic acid; 2700 mg/kg nicotinic acid; 300 mg/kg vit. B6; 4 mg/kg Vit. B7; 100 mg/kg vit. B9; 1.8 mg/kg vit. B12; 2000 mg/kg vit. C; 8000 mg/kg manganese; 8000 mg/kg iron; 500 mg/kg copper; 6000 mg/kg zinc; 37 mg/kg cobalt; 152 mg/kg iodine; 18 mg/kg selenium.

Table 2. Chemical composition of the supplements used in the experiment.

Parameters*	OP	GP
Proximate composition
Crude protein, %	4.85	5.39
Crude fat, %	1.10	0.95
Crude fibre, %	9.70	11.82
Ash, %	2.95	3.51
Antioxidant compounds
Vitamin E, mg/kg	100.50	89.93
Lutein and zeaxanthin, mg/kg	81.52	36.46
Polyphenols, mg/g	8.035	12.162
Zinc, mg/kg	4.74	5.41
Antioxidant capacity, mmoli/kg equiv. ascorbic acid	238.51	238.25
Antioxidant capacity, mmoli/kg equiv. vitamin E	231.33	227.75

*Results reported as dry weight basis.

Table 3. Productive performance (14–42 days).

Parameter	C	OP	GP	SEM	p Value
Initial BW, (g)	440.68	440.73	440.90	4.091	.9997
Final BW, (g)	2925.59^a	2966.70^a	2768.81^b	22.817	.0007
DWG, (g)	88.75^a	90.21^a	83.14^b	0.832	.0009
ADFI, (g CF/chick/day)	143.88	142.39	138.47	3.248	.7852

^a,b,cMeans within a row with no common superscript differ (p < .05). BW, (g) – body weight; DWG (g), daily weight gain; ADFI (g CF/chick/day) – average daily feed intake; CF – compound feed.

Figure 1. a,b,c. Effect of dietary OP and GP supplements on energetic parameters from blood serum (ml/dl). Where: ^{a, b}Means within a row with no common superscript differ (P< 0.05). C = control diet; OP = control diet supplemented with orange peel; GP= control diet supplemented with grapefruit peel.

Table 4. Fatty acids composition in thigh meat.

Specification	g /100g total fatty acids
	C	OP	GP	SEM	p Value
Myristic C 14:0	0.543	0.522	0.522	0.005	.0953
Myristoleic C 14:1	0.10^a	0.11^b	0.12^c	0.002	<.0001
Pentadecanoic C 15:0	0.11^ab	0.13^a	0.13^b	0.003	.0021
Pentadecenoic C 15:1	0.14^a	0.18^ab	0.14^b	0.007	.0167
Palmitic C 16:0	18.82^a	18.62^b	19.51^ab	0.106	<.0001
Palmitoleic C 16:1	3.43^a	3.91^b	4.38^c	0.096	<.0001
Heptadecanoic C 17:0	0.20^a	0.20^b	0.18^ab	0.003	<.0001
Heptadecenoic C 17:1	0.13^a	0.13^b	0.11^ab	0.003	.0091
Stearic C 18:0	6.65^ab	5.91^a	5.96^b	0.092	<.0001
Oleic cis C 18:1n9	32.63^ab	33.99^a	34.40^b	0.217	<.0001
Linoleic C 18:2n6	28.55^a	28.77^a	27.26^b	0.176	<.0001
Linolenic C 18:3n6	0.13^a	0.15^a	0.12^b	0.003	.0060
Linolenic α C 18:3n3	2.00^a	2.08^b	1.93^c	0.018	<.0001
Conjugated linoleic acidC 18:2	0.20	0.17	0.19	0.014	.7950
Octadecatetraenoic C 18:4n3	0.21^ab	0.29^a	0.33^b	0.018	.0160
Eicosadienoic C 20:2n6	0.20^a	0.18^ab	0.32^b	0.024	.0205
Eicosatrienoic C 20:3n6	0.46^ab	0.35^a	0.32^b	0.015	<.0001
Erucic C22:1n9	0.07	0.06	0.05	0.003	.1828
Eicosatrienoic C 20:3n3	0.42^ab	0.33^a	0.31^b	0.013	<.0001
Arachidonic C20:4n6	2.42^a	1.76^b	1.55^ab	0.100	<.0001
Docosadienoic C22:2n6	0.20^a	0.23^b	0.21^c	0.005	.0010
Docosatrienoic C22:3n6	0.11^a	0.15^b	0.13^c	0.004	<.0001
Eicosapentaenoic C 20:5n3	0.21^a	0.25^b	0.24^c	0.005	<.0001
Lignoceric C 24:0	0.27^ab	0.29^a	0.29^b	0.005	.0477
Nervonic C 24:1n9	0.69^ab	0.42^a	0.40^b	0.034	<.0001
Docosatetraenoic C22 :4n6)	0.12	0.09	0.10	0.012	.6006
Docosapentaenoic C 22:5n3	0.31^ab	0.21^a	0.23^b	0.013	.0013
Docosahexaenoic C 22:6n3	0.20^ab	0.16^a	0.14^b	0.007	.0009
Other fatty acids	0.30^ab	0.11^a	0.13^b	0.027	.0018
SFA	26.69	26.69	26.73	0.086	.9756
MUFA	37.20^a	38.82^b	39.64^c	0.271	<.0001
PUFA	35.80^a	35.24^a	33.48^b	0.262	<.0001
n-3	3.37^a	3.36^a	3.19^b	0.028	.0090
n-6	32.22^a	31.71^b	30.09^c	0.237	<.0001
n-6 / n-3	9.560	9.450	9.410	0.053	.5431

^a,b,cMeans within a row with no common superscript differ (p < .05). SFA: saturated fatty acids; PUFA: polyunsaturated fatty acids; MUFA: monounsaturated fatty acids.

Figure 2. Effect of dietary OP and GP supplements on TBARS concentration evolution in time (0 and 7 days). Where: ^{a, b, c}Means within a row with no common superscript significantly differ (p < 0.05). C = control diet; OP = control diet supplemented with orange peel; GP = control diet supplemented with grapefruit peel.

Table 5. Effect of OP and GP on broilers intestinal microbial population from small intestine and caecum (log ₁₀).

Item	C	OP	GP	SEM	p Value
Small Intestinal Content
Enterobacteriaceae	7.436^a	7.385^b	7.386^b	0.006	<.0001
Escherichia coli	6.097^a	6.032^b	6.025^b	0.006	<.0001
Staphylococcus spp.	5.672^a	5.566^b	5.537^c	0.014	<.0001
Lactobacillus spp.	7.413^a	7.442^b	7.444^b	0.004	<.0001
Salmonella spp.	Absent	Absent	Absent	n/a	n/a
Caecal Content
Enterobacteriaceae	11.372	11.202	11.362	0.055	.3923
Escherichia coli	10.076^a	10.000^b	10.011^b	0.008	<.0001
Staphylococcus spp.	8.806^a	8.820	8.782^b	0.006	.0366
Lactobacillus spp.	11.645^a	11.906	12.022^b	0.038	<.0001
Salmonella spp.	Absent	Absent	Absent	n/a	n/a

Values are expressed as logarithm base 10.

^{a, b, c}Means within a row with no common superscript significantly differ (p < 0.05). n/a = not applicable; SEM = standard error of the mean; C = control diet; OP = control diet supplemented with orange peel; GP = control diet supplemented with grapefruit peel.