Impact of dietary supplementation with cinnamon bark powder on broiler growth and carcass indices, small intestinal measurements, physico-chemical properties of meat and economics of production

Abstract

The purpose of this study was to assess the possible impacts of cinnamon bark powder (CBP) on broiler chicken productivity in 34 days, body composition, meat physicochemical traits, and economics of broiler production. A total of 120 one-day-old Ross 308 broilers were in a completely randomized design (CRD) assigned to four treatments: 0, 2, 4, and 6 g CBP/kg basal diet (5 pens/treatment with 6 birds/pen). Growth and carcass indices, small intestinal (SI) dimensions, physicochemical properties, and efficiency of production were calculated. The results showed that feed consumption, feed cost, body composition, and breast color quality, except yellowness, were not affected by the treatments. The birds fed 2 g CBP/kg meal had greater (P < 0.05) width and thickness of the SI and its sections than the control group and had the highest growth, production efficiency, and profitability ratios compared to other CBP groups. The pH of meat dropped considerably at increasing levels of dietary CBP. In conclusion, the addition of CBP, especially at a level of 2 g, had a positive effect on the SI dimensions, growth indices, and economic profitability of the broilers without altering their carcass traits or meat quality attributes.

Keywords:

• broilers
• carcass indices
• cinnamon bark
• growth
• economic profitability
• small intestine dimensions

PUBLIC INTEREST STATEMENT

Antibiotics and their natural alternatives have competed in broiler feeding, but many governments are restricting antibiotic use because of concerns about residues and germ resistance in humans. Although previous research has been conducted to investigate the effects of the cinnamon plant as a feed additive for broilers because it has multiple effects and improves digestion, results have been inconsistent and variable. Therefore, the study of the feasibility and efficacy of the cinnamon plant in broilers is still limited, which gives priority for this study.

1. Introduction

There is a yearly global increase in population and food demand (Pawlak & Kołodziejczak, 2020; Van Dijk et al., 2021). Poultry is a prominent source of animal protein worldwide. To meet the worldwide demand for poultry products, nutrition must be improved in order to sustain the poultry industry. On the other hand, the poultry industry, particularly in developing countries, faces several challenges, including shortages of foodstuffs, availability and feasibility of conversion of feed to meat, the banning of antibiotics as growth promoters, etc (El-Sabrout et al., 2023). Feed additives are a successful strategy for increasing poultry farmers’ earnings. As a result, there is an urgent need to incorporate accessible nutraceuticals into the diet to sustain poultry production. Phytogenics are used in broiler diet and play important economic and productive efficiency roles by influencing body weight (BW) and feed-to-meat conversion ratio (Abdel-Wareth et al., 2019; Hussein & El-Kassas, 2023; Krauze et al., 2021).

Cinnamon tree, especially the inner bark, can be used as a natural feed additive in broiler diets because it contains a variety of phytochemicals, including cinnamaldehyde, eugenol, camphor, caryophyllene, and a variety of phytonutrients, micronutrients, and macronutrients (Al-Garadi et al., 2023; Yaqoob et al., 2022). Cinnamon has antioxidant, antibacterial, antiparasitic, anti-inflammatory, antiallergic, antihyperglycemic, antihypercholesterolemic, and detoxifying properties (Ali et al., 2021; Noshirvani et al., 2017; Sharma et al., 2016; Sun et al., 2016; Yaqoob et al., 2022). Consequently, cinnamon as a natural spice can increase appetite, promote the release of digestive enzymes in the gut, act as a food preservative, and strengthen the immune system, thus improving broiler performance and increasing the economic efficiency of production (Ali et al., 2021; Krauze et al., 2021; Meligy et al., 2023; Metwally, 2023; Vangalapati et al., 2012; Zawani et al., 2022).

Several studies have used cinnamon bark powder in broiler diets to enhance the performance, health, and carcass characteristics of poultry and to increase the safety and economy of poultry diets. Nevertheless, the doses employed varied greatly (0.20–70 g equal 0.02–7%), and the results were inconsistent (Faghani et al., 2014; Hussein et al., 2016a; Islam & Nishibori, 2023; Sang-Oh et al., 2013; Toghyani et al., 2011).

The studies on the effect of cinnamon in the poultry sector showed different results in terms of performance: improved (Beg et al., 2016; Hussein & El-Kassas, 2023; Hussein et al., 2016a; Khafaji, 2018), not affected (Islam & Nishibori, 2023; Lee et al., 2003) or negative (Chowlu et al., 2019; Sadeghi et al., 2012). Another study found that cinnamon improved health without affecting performance (Islam & Nishibori, 2023).

There is limited literature or inconsistent reports on the economic benefits of cinnamon as a natural feed additive for poultry. From an economic perspective, cinnamon has improved poultry profitability ratios (Gaikwad et al., 2019; Ghanem et al., 2021; Hussein & El-Kassas, 2023), or shown no positive effects (Chowlu et al., 2019). The two most important issues in broiler production are production costs and yields. The questions of how much a bird costs and how much it earns are quickly becoming the most important formulas in poultry economics. Thus, the profitability of poultry enterprises can be increased if key production cost standards are established and closely monitored (Bandara & Dassanayake, 2006; Romero et al., 2010). The ability of broilers to convert feed into meat is critical to the profitability of the broiler industry. Feed costs around 70% of overall production expenses in the broiler production business, making a bird’s capacity to use feed efficiently critical (Willems et al., 2013). Consumers around the world are becoming increasingly aware of the nutritional value and safety of their food and its ingredients. In chicken nutrition, it is well known that feed costs are the most expensive item in the entire production process. Therefore, efforts are often made to reduce feed costs without compromising performance or product safety (Hassan et al., 2021; Hussein & El-Kassas, 2023; Osman et al., 2010).

In the present study, it was hypothesized that the addition of cinnamon bark powder (CBP) to the diet of broiler chickens in an appropriate proportion would improve their body composition, the quality of their breast meat color, the developmental size of their SI, and economic feasibility without any adverse effect.

Cinnamon bark powder doses investigated in previous studies differ from one study to the next, ranging from 0.2 to 70 g (i.e., 0.02% to 7%), and so findings vary (Faghani et al., 2014; Hussein et al., 2016b; Sang-Oh et al., 2013; Toghyani et al., 2011). To check the reasonable Cinnamon bark powder doses used in preceding studies and to find the best choice for current dosages, we decided to use moderate amounts of cinnamon. Therefore, the purpose of this study was to assess the possible impacts of the addition of natural CBP on growth and carcass indices, SI measurements, physico-chemical properties of meat, and economics of production.

2. Materials and methods

2.1. Ethical approval

When conducting the study, the King Saud University (KSU) Animal Care & Welfare Committee’s guidelines (Approval No: KSU-SE-20-44) were followed.

2.2. Birds, diets, and experimental design

The study was carried out at the experimental unit of poultry production, KSU, Riyadh, Saudi Arabia. A total of 120 one-day-old Ross 308 chicks were weighed individually and in a CRD assigned into 20 replicates of 6 birds each (3♂ and 3♀), to minimize variances in BW between groups. Chicks were housed in electrically heated battery cages. Using cool light fluorescent bulbs, the photoperiod was maintained at 23 L:1 D at an intensity rate of 20 lux. The experimental diet was assigned to one of four meals with CBP content of 0, 2, 4, and 6 g/kg during starter (1–21) and finisher (22–34 days old) periods (Supplementary Table S1). The CBP was mixed with rice bran as a carrier and added on top of the broiler diets except for the control group. The broilers were given ad libitum feed and water. According to Rostagno et al. (2011), calculated values were analyzed on an as-fed basis (%).

Dried cinnamon bark was purchased and ground in a Nutrition Lab using a grinder (Moline M-06, Italy). Samples of CBP were analyzed for macronutrients according to the American Association of Cereal Chemists (AACC, 2000). The outcomes of the proximate analysis from our previous work by Qaid et al. (2021) indicated that cinnamon is a good dietary fiber source in poultry diets. The bioactive components of CBP (cinnamaldehyde and other 25 volatile fatty acids) were detected by HPLC and GC/MS analysis in our previous study (Qaid et al., 2021).

2.3. European Production Efficiency Factors (EPEF)

Average BW; kg: at d 0 and d 34 of age, viability, and FCR were measured to determine production efficiency. EPEF = ((100 – mortality)* live weight (kg))/(weighted age (d)* FCR)*100 (Awad et al., 2009). During 0–34 days of age, total BWG, cumulative feed intake, and FCR (feed: gain) were calculated.

2.4. Carcass characteristics and small intestine measurements

On the 34^th day of life, five birds/group (1 chicken from each pen) were randomly chosen for slaughter to measure SI parts and carcass yield as stated by Shafey et al. (2013). The selection of 5 birds/treatment for small intestinal and carcass evaluation was done following the methods prescribed by Bawish et al. (2023) and Abdullah et al. (2010). Chickens were fasted for 9 hours before being euthanized by neck dislocation, scalded, feathered by hand, and eviscerated. Body parts, giblets (gizzard, liver, and heart), and SI were collected for measurements. Carcass weight, abdominal fat, and cuts (breast, leg “thigh plus drumstick”, back, and wing) were all recorded. Carcass weight was determined after the head, skin, feathers, abdominal fat, and viscera were removed. Carcass yield (%) was calculated as a relative of carcass weight to live weight.

The SI parts (duodenum, jejunum, and ileum) were carefully removed and then rinsed with saline to remove any residual SI contents. Each part’s weight, length, and thickness were recorded. The weights of the SI segments were given in absolute (g) or percentage of living weight (%) values.

2.5. Breast meat quality indicators in relation to colour and pH

Physicochemical quality indicators (pH and color) were measured 1-hour postmortem, with an average of three pH values and two color components at different areas of the inner surface of the pectoralis major of each sample. In addition, pH was measured 24 hours’ postmortem. A Hanna Instruments pH meter with a microprocessor was used. Measurements of breast flesh color: lightness (L*), redness (a*), and yellowness (b*) were set on CIELAB scales and evaluated with a Chroma meter. To obtain a much more accurate evaluation of consumer perception of meat color, total color change (∆E), saturation index, hue angle, and browning index (BI) were estimated as cited by Cázares-Gallegos et al. (2019).

2.6. Economic efficiency of the broiler diet and production

An economic analysis and profitability ratios of the experimental diet and poultry production were calculated using input-output analysis according to the market price of the feed and broilers in Saudi Arabia at the time of the trial. A partial budget analysis was performed to evaluate the economic benefits of the different CBP treatments. An economic analysis was performed to calculate feed costs and revenues, as shown below:

Total cost of feed = total actual feed intake per bird during the feeding period * the prevailing cost of 1 kg of feed. Feed cost/kg BWG = FCR*cost of 1 kg of feed for the full feeding period at predominant prices (Al-Khalaifah et al., 2020).

Total cost (TC) of production = fixed cost + total feed cost. The fixed cost of all groups is 0.96 dollars and the selling cost of kg⁻¹ meat is 1.58 dollars.

Total revenue (TR) = average live weight of each bird throughout the study × market price in Saudi Arabia per kg of meat. Selling cost of kg-1 meat = 1.58$. Net revenue (NR) = TR-TC.

Profitability ratios were used to explain how much of the factors of production were used to maximize profit and were calculated according to Ibrahim et al. (2021) and Chowlu et al. (2019).

Benefit-cost ratio (BCR) = TR/TC.

Rate of returns on investment (RRI, %) = (NR/TC)*100.

Profitability index (PI) = NR/TR.

Economic efficiency (EE) = NR/feed cost per kg of gain.

2.7. Statistical analysis

The collected data were statistically analyzed by using the general linear model (GLM) of the statistical analysis system SAS (2012) in one-way ANOVA.

The following is a description of the model equation:

${\gamma }_{ij}=\mu +T_i+e_{ij}$

Where Y_ij is the individual observation; µ is the general investigational mean, T_i is the effect of the i^th treatment, and e_ij is the residual error with assumptions that data is normally and independently distributed with mean and σ² is equal to zero.

Before carrying out the ANOVA, the Kolmogorov-Smirnov test was performed to check the normal distribution of the analyzed indicators. All percentage data were arcsine-transformed before analysis. Results are reported as statistical mean ± standard error mean (SEM). Orthogonal polynomial contrasts were used to determine whether the response to incremental concentrations of CBP was linear or quadratic. Welsch Multiple Range Test was performed to compare significant variations between groups. The test for statistical significance was set at P ≤ 0.05.

3. Results

3.1. European Production Efficiency Factors

The EPEF value for broiler chick performance is shown in Figure 1. The EPEF value was highest in the group that received 2 g of cinnamon powder per kg of feed (395) compared to the other groups. These values indicate that the performance of the groups supplemented with 2 g CBP was better than that of the other CBP groups. As shown in Figure 2, the 2 g CBP/kg diet had higher BW (1.864 kg in the group treated with 2 g CBP) compared to other CBP-treated groups and similar to the control group, and feed conversion (1.40 in the group treated with 2 g CBP) compared to other groups and good viability in the given number of days. Throughout the experiment, no mortalities were observed.

Figure 1. European production efficiency factors (EPEF) for treatments containing 0, 2, 4, or 6 g cinnamon bark powder per kg of diet (P = 0.078; cubic 0.02; SEM ± 11.16). EPEF = (viability% × live weight (kg))/(weighted age (d) * feed conversion ratio) × 100.

Figure 2. Body weight at 34 days (kg, SEM 0.303; p-value 0.054; cubic 0.0226) and feed conversion ratio (FCR: kg feed/kg gain; SEM 0.025; p-value 0.338).

3.2. Carcass traits

The effects of diets supplemented with different levels of CBP on the carcass composition of broilers are shown in Table 1. Slaughter BW, carcass yield, and body components (eviscerated carcass, abdominal fat, neck, edible offal, breast, leg, wing, and back) of broilers were not affected (P > 0.05) by the diets supplemented with different amounts of CBP.

Table 1. Carcass composition of broiler chickens at 34 days of age fed diets containing varying amounts of cinnamon bark during the experimental period

Treatment^1	Cinnamon levels (g/kg)^1				SEM^2		Contrast
Body composition	0	2	4	6		p-value	Linear	Quadratic
Live body weight (g)	1658^ϒ	1816	1777	1752	61.5	0.42	0.35	0.21
Eviscerated carcass (g)	1103	1212	1178	1151	41.8	0.64	0.32	0.50
Carcass yield (%)	66.49	66.66	66.29	65.69	2.10	0.53	0.34	0.35
(g/kg Live body weight)
Abdominal fat	7.87	7.02	8.10	6.29	0.88	0.47	0.37	0.59
Neck	25.9	23.4	24.0	25.2	1.2	0.49	0.79	0.15
Edible offal^3	43.7	47.7	51.0	45.7	2.1	0.11	0.31	0.04
Eviscerated carcass	664.3	633.1	663.2	656.0	12.0	0.34	0.90	0.30
(g/kg Eviscerated carcass)
Leg	309	302	332	307	9.48	0.15	0.56	0.36
Breast	390	411	379	406	13.04	0.33	0.78	0.80
Back & wing	250	240	241	239	18.99	0.98	0.72	0.85

¹Basal diet with Cinnamon at levels 0, 2, 4, and 6 g/kg. ²SEM, standard error of mean. ^ϒMean of five bird per treatment. ³Edible offal= Liver weight + heart weight + gizzard weight.

3.3. Small intestine measurements

The effects of the amount of CBP in the diet on the SI readings of broilers are shown in Table 2. Increasing the CBP content from 0 to 4 g CBP/kg diet significantly increased the absolute and relative duodenal weight to live weight (P = 0.0003, quadratic P < 0.0001), duodenum thickness (P = 0.001, quadratic P < 0.0001), ileum weight per gram and as a % of live weight (P = 0.025, quadratic P < 0.006), and ileum thickness (P = 0.012, quadratic P < 0.002). In addition, increasing CBP content from 0 to 4 g CBP/kg feed resulted in a significant increase in total weight SI per g and intestinal relative (P = 0.011, quadratic P < 0.002), and total thickness SI (P = 0.002, quadratic P = 0.0001). Jejunal weight per g or % live weight tended to increase with increasing cinnamon dose up to 4 g CBP/kg diet (P = 0.09, quadratic P < 0.03). Jejunal thickness tended to increase with increasing cinnamon dose up to 4 g CBP/kg diet (P = 0.06, quadratic P = 0.012). Although the 2 and 4 g CBP groups had higher absolute ileum weight and ileum thickness than the 6 g CBP group, the differences between the 2 and 4 g CBP groups were not significant.

Table 2. Measurements of the small intestine (SI) of broiler chickens at 34 days of age fed diets containing different amounts of cinnamon bark powder

Treatment^1	Cinnamon levels (g/kg)				SEM^2	Contrast
Small intestine (SI) measurements	0	2	4	6		p- value	Linear	Quadratic
Duodenum length (L, cm)	27.0	28.8	28.3	27.3	1.002	0.574	0.951	0.187
Duodenum absolute weight (W, g)	7.18^b	10.3^a	11.7^a	8.0^b	0.614	0.0003	0.186	<0.001
Duodenum relative weight (% BW)	0.42^b	0.61^a	0.69^a	0.47^b	0.036	0.0002	0.187	<0.001
Duodenum thickness (W/L, g/cm)	0.27^c	0.36^ab	0.41^a	0.29^bc	0.02	0.001	0.164	<0.001
Jejunum length (L, cm)	69.5	68.5	75.3	72.8	2.333	0.196	0.133	0.752
Jejunum absolute weight(W, g)	17.0	18.8	21.7	17.4	1.322	0.091	0.496	0.036
Jejunum relative weight (%BW)	1.00	1.11	1.28	1.03	0.078	0.095	0.499	0.038
Jejunum thickness (W/L, g/cm)	0.24	0.27	0.29	0.24	0.014	0.062	1.00	0.012
Ileum length (L, cm)	70.5	71.3	77.5	73.5	2.554	0.249	0.201	0.365
Ileum absolute weight (W, g)	13.9^b	18.1^ab	20.2^a	15.8^ab	1.342	0.025	0.222	0.006
Ileum relative weight (%BW)	0.82^b	1.07^ab	1.19^a	0.93^b	0.08	0.025	0.215	0.006
Ileum thickness (W/L, g/cm)	0.20^b	0.25^a	0.26^a	0.22^ab	0.013	0.012	0.282	0.002
SI length (L, cm)	167	169	181	174	4.804	0.202	0.156	0.363
SI absolute weight (W, g)	38.1^b	47.2^ab	53.6^a	41.2^b	2.996	0.011	0.264	0.002
SI relative weight (IRW; % BW)	2.25^b	2.79^ab	3.16^a	2.43^b	0.177	0.011	0.268	0.003
SI thickness (W/L, g/cm)	0.23^c	0.28^ab	0.30^a	0.24^bc	0.012	0.002	0.369	0.0001

¹The treatments were basal diets containing cinnamon bark at levels of 0, 2, 4, and 6 g/kg. ²SEM, standard error of the mean. ^ϒMean of five replicates per treatment. ^abc Mean values in the same row with different superscript letters indicate significant differences (P < 0.05).

3.4. Breast meat quality indicators in relation to colour and pH

The physicochemical meat characteristics of broiler chickens fed different levels of CBP are shown in Table 3. The pH_1 h and pH_24 h values and pH decline values of breast meat postmortem differed significantly (P < 0.05) between treatment groups.

Table 3. Effect of feeding cinnamon bark as a natural preservative on initial and ultimate pH and color quality 1 h post mortem of broiler chickens at 34 days of age

Treatment^1	Cinnamon levels (g/kg)				SEM^2		Contrast
Parameter	0	2	4	6		p-value	Linear	Quadratic
pH1 h	6.08^cϒ	6.22^bc	6.27^b	6.43^a	0.046	<0.001	0.046	<0.001
pH24 h	5.78^b	5.90^a	5.78^b	5.80^b	0.013	<0.001	0.404	0.001
pH decline	0.31^b	0.31^b	0.49^a	0.63^a	0.044	<0.001	0.051	<0.001
L* (Lightness)	42.12	42.52	44.36	44.46	0.707	0.064	0.01	0.84
a* (Redness)	6.59	6.20	5.90	5.39	0.584	0.539	0.16	0.92
b* (Yellowness)	7.70^ab	8.10^a	8.16^a	7.11^b	0.254	0.036	0.16	0.01
Total color change	52.71	52.27	50.41	50.17	0.732	0.057	0.01	0.89
Saturation index	10.28	10.2	10.08	8.92	0.469	0.179	0.06	0.27
Hue angle (◦)	50.86	52.68	54.27	52.94	2.445	0.804	0.48	0.53
Browning index	31.50	31.41	29.68	25.95	1.705	0.114	0.03	0.30

¹Basal diets containing cinnamon bark at levels of 0, 2, 4, and 6 g/kg. ²SEM, standard error of mean; ^ϒmean of five replicates per treatment. ^abc Means in the same row with different superscript letters indicate significant differences (P < 0.05).

The addition of CBP resulted in a rise in pH 1 h postmortem with increasing cinnamon level (P = 0.001, linear P < 0.0001). Although the pH_24 h was the highest value, the pH decline was considerably accelerated as CBP levels increased (P < 0.001, linear 0.051, quadratic P < 0.001). As shown in Table 3, feeding broiler chickens with different levels of CBP significantly affected yellowness (b*) 1 h postmortem. Cinnamon at levels 2 g and 4 g increased yellowness significantly (P = 0.036, quadratic P = 0.01) compared to 6 g CBP/kg, but did not differ from the control. Increasing CBP content increased lightness (P = 0.064, linear P = 0.013) and decreased total color change (P = 0.057, linear P = 0.0104) with increasing cinnamon content. Diets supplemented with varying amounts of CBP had no effect on redness, saturation index, or hue angle (P > 0.05). The BI decreased linearly (P = 0.03) but was not significant (P = 0.114).

3.5. Economic efficiency of broiler diet

The cost and profitability ratios of CBP supplementation are shown in Table 4. There was a significant difference (P ≤0.05) between CBP-treated groups in the profitability values, but there were no differences (P > 0.05) in expense values. Despite the fact that the feed costs increased significantly with increasing CBP levels, total feed costs per bird ($) did not differ significantly with increasing CBP doses because feed intake (FI) was the same between groups (P > 0.05). Profitability ratios differed considerably between CBP groups (2 g CBP versus 4 or 6 g CBP), but CBP groups were significantly similar to the control group. Thus, feeding broilers a diet containing 2 g CBP resulted in the highest (linearly and cubic trends; P ≤0.05) net revenue ($0.90), benefit-cost ratio (1.44), profitability index (0.302), investment rate (43.7), economic efficiency (74.7%), relative economic efficiency (110.3%), and profitability rate/kg meat (1.10). The profitability ratios were similar in the groups receiving meals containing 4 and 6 g CBP/kg. Although the cost of the cinnamon diet was numerically higher than the cost of the non-cinnamon diet, the group receiving 2 g CBP/kg outperformed the non-cinnamon diet group in terms of BW and BWG. Thus, the profitability ratios of the group receiving 2 g CBP/kg were slightly higher than those of the group receiving the diet without cinnamon, although not significant (P > 0.05).

Table 4. Effect of different amounts of cinnamon bark powder on the cost and profitability of broilers

Treatment^1	Cinnamon levels^1 (g/kg)				Standard Error		Contrast
Parameter	0	2	4	6		p-value	Linear	Quadratic	Cubic
Feed intake kg at 34 d	2.516^ϒ	2.532	2.475	2.45	0.012	0.474	0.17	0.62	0.56
Cost kg − 1diet*	0.423^d	0.430^c	0.438^b	0.445^a	0	<0.01	<0.01	0	<0.01
Total feed cost/bird, $	1.06	1.09	1.08	1.09	0.017	0.647	0.33	0.54	0.57
Gain, kg (1–34 days)	1.735	1.879	1.821	1.814	1.76	0.057	0.23	0.3	0.02
Feed cost/kg weight gain, $ (ECR)	0.61	0.6	0.64	0.64	0.011	0.119	0.06	0.66	0.15
Total costs (TC), $	2.02	2.05	2.04	2.05	0.018	0.647	0.33	0.54	0.57
Total returns (TR), $ (Total meat price)	2.82	2.94	2.77	2.79	0.048	0.056	0.24	0.29	0.02
Net revenue/kg gain, $	0.79^ab	0.90^a	0.72^b	0.74^b	0.043	0.033	0.09	0.36	0.02
Benefit—cost ratio (BCR)	1.39^ab	1.44^a	1.35^b	1.36^b	0.021	0.031	0.05	0.37	0.03
Profitability index (PI), $	0.281	0.302	0.26	0.263	0.012	0.054	0.07	0.36	0.06
Rate returns investment (RRI, %)	39.2^ab	43.7^a	35.4^b	36.0^b	2.07	0.028	0.06	0.36	0.02
Economic efficiency (EE %)	74.7^ab	82.4^a	66.9^b	67.6^b	3.96	0.031	0.05	0.38	0.03
Relative economic efficiency (REE)	100.0^ab	110.3^a	89.6^b	90.6^b	4.86	0.016	0.03	0.35	0.02
Profitability ratio/kg meat, (RPR)	1.000^ab	1.103^a	0.896^b	0.906^b	0.49	0.016	0.03	0.35	0.02

*Cost 1 kg diet (including cost of g cinnamon/kg diet) “1 kg cinnamon price = 3.71$) based on according to the price at the time of experiment (local price for one kg of basic diet and cinnamon), fixed cost of all groups = 0.96$ and selling cost of kg-1 meat = 1.58$. ^abc Mean values in the row with different superscript letters indicate significant differences (P < 0.05). ¹ Basal diets containing cinnamon bark at levels of 0, 2, 4, and 6 g/kg. ²SEM standard error of the mean; ^ϒn = five replicates cages per treatment. *Assuming the relative economic efficiency and profitability ratio per kg meat of control diet is equal to 100 and 1, respectively.

4. Discussion

Cinnamon could be used as a natural growth promoter in broiler diets to improve gut health and thus growth performance (Saied et al., 2022). Cinnamon contains active phenolic and flavonoids combinations that have therapeutic and antioxidant properties (Ahmadi & Shahri, 2020; Khezeli et al., 2016; Oso et al., 2019). The experimental treatments did not affect the weights (%) of internal organs as reported by Toghyani et al. (2011).

Feeds containing cinnamon, especially 2 g/kg feed, outperformed the other CBP groups in terms of growth, FCR, and productive efficiency. Toghyani et al. (2011) recommended that dietary 2 g/kg cinnamon could be used as an antibiotic replacement because their outcomes, which were comparable to ours, showed an increase in BW, a decrease in FCR, and an unchanged FI in broilers at day 28. This improvement in performance with the addition of CBP (2 g/kg) to broiler diets could be related to the influence of active components (such as cinnamaldehyde and eugenol) from cinnamon bark. These compounds are classified as digestive enhancers because they increase the secretion of endogenous digestive enzymes, protect the intestinal villi through intercellular antioxidant activity, and improve nutrient absorption (Jamroz et al., 2006). In line with Khan et al. (2003) and Hameed et al. (2016), cinnamaldehyde is the most abundant compound in cinnamon, followed by carvacrol and eugenol. Moreover, these bioactive compounds have antioxidant possessions (Bhavaniramya et al., 2019; Favaretto et al., 2020). The inclusion of cinnamon (4 g/kg feed) in the diet of Japanese quail improved carcass performance compared to the control group (Metwally, 2023).

The results of this study agree with those of Islam and Nishibori (2023), who found that no significant difference was observed between CBP diets in terms of growth and meat yield. However, they found that diets containing 4, 6, or 8 g of cinnamon per kg of feed performed better than 0 g of cinnamon/kg of feed) in terms of blood lipid profiles and sensory meat attributes and flavor. This may indicate that cinnamon has higher health and flavor benefits than performance benefits under typical rearing conditions. In harmony with Saied et al. (2022), they observed that carcass characteristics were not affected by treatment with cinnamon oil.

Because it is the site of nutritional digestion and absorption, the SI is the most significant section of the gastrointestinal tract (GIT) (Ravindran & Abdollahi, 2021). Greater surface area improves digestion and assimilation of nutrients and consequently maximizes BW (Geyra et al., 2001). Cinnamon and its derivatives such as cinnamaldehyde, eugenol, and carvacrol have antimicrobial activity due to their preventive effect on pathogenic microorganisms (Al-Garadi et al., 2023; Meligy et al., 2023). Intestinal measurements revealed that increasing amounts of CBP in the diet amplified the weight and thickness of the SI and its parts. Shafey et al. (2013) found a similar result when they showed that consumption of 15 and 30 g of olive leaves in broiler diets had no effect on broiler performance and carcass parameters. However, they found that feeding 50 g olive leaves/kg to broiler chickens affected SI measures and decreased live and slaughter weights. The increase in SI weight and thickness in birds fed up to 4 g/kg CBP seems to be a type of SI physical adaptation to a high-fiber regime that could allow birds to consume more diet and absorb more nutrients. Fiber intake has been shown to improve weight, volume, and GIT capacity in numerous species (Shafey et al., 2013). Cinnamon has a rather bitter taste and a pungent, spicy aroma, which may influence appetite and FI acceptance. According to Chowlu et al. (2019), the use of CBP, irrespective of quantity, had no effect on FI, which is likely due to broiler chickens being more tolerant of the smell and taste of cinnamon (sweet and spicy aroma). Moreover, Qaid et al. (2021) observed that in proximate analysis, crude fiber, acidic and neutral detergents, crude protein, ash, and gross energy were 24.35%, 45.75%, 65.34%, 4.43%, 3.18%, and 4974.52 kcal/kg, respectively, demonstrating its suitability as a dietary supplement. Consequently, CBP has the potential to be used as a dietary fiber source in broiler diets. As a result of the higher dietary fiber content of CBP, intestinal thickness and weight increased. In addition, CBP (2 g CBP/kg meal) increased duodenal architecture and the amount of Escherichia coli in the caecum after 10 days of life compared to the control (Qaid et al., 2021).

As shown in Figure 1, the EPEF value for broiler performance was numerically higher in the group treated with 2 g CBP (395) than in the group treated with 0 g CBP (363), indicating that the group treated with 2 g CBP performed better than the control group. When compared to other CBP groups, the 2 g CBP-treated group positively affected EPEF by positively affecting BW (1.864 kg) and FCR (1.40) (Figure 2), which represents the overall economic efficiency of the birds considering various important traits. The current study supports Kumar et al. (2018), who found that the basal feed group with cinnamon powder at a dose of 250 mg/quintal feed (414.61) had a higher EPEF value than the control group (300.37). The optimal dose of cinnamon for higher FI was 5 g/kg feed, while the best live weight was obtained in the group treated with 7.5 g/kg feed (Beg et al., 2016). In the experiment, the dietary treatments had no effect on mortality. This demonstrated that the broilers were reared under normal conditions. According to Gaikwad et al. (2019), there was no mortality observed across groups when ginger and cinnamon were added to the diets of broiler chickens.

Cinnamon from Lauraceae is a potential source of potent natural antioxidants for commercial use (Shan et al., 2005). Consequently, natural antioxidant supplementation of broiler diet may have desirable effects on the meat, provided that the quality of broiler meat does not show deleterious effects when consumed. Fifteen minutes postmortem, the pH parameter was a good judge of meat quality (Fletcher, 2002) and ranged between 5.78 and 6.59 (Dodge & Peters, 1960). The lower initial pH of the pectoral muscle in birds was attributed to the continuous tonicity in the pectoral muscle, which led to the breakdown of glycogen and accumulation of lactic acid in the pectoral muscle, resulting in a lower initial pH. However, since any stress, such as transport and feed deprivation prior to slaughter, causes fatigue, bird activity is minimized (Kannan et al., 1997). In agreement with Kannan et al. (1997), a lower initial pectoral muscle pH reflects a higher level of glycolysis in the birds of the control group than in the birds of the CBP-treated groups, suggesting a lower level of stress prior to slaughter in the birds of the cinnamon treated groups. Here, the CBP groups showed less color change, higher yellow coloration, and a tendency toward more brightness compared with the control groups. In agreement with Galli et al. (2020), they found that broilers fed a combination of phytogens such as cinnamaldehyde, thymol, carvacrol, and curcumin showed higher yellow intensity in the meat (Hughes et al., 2014).

From an economic standpoint, the highest dose of cinnamon resulted in the highest feed cost per kg of live BWG, and vice versa. According to the input-output analysis, the 2 g CBP-treated group had the highest relative economic efficiency and other profitability ratios. These results are in agreement with the findings of Kumar et al. (2018), who found that the feed cost per kg of live weight was lowest in the group that received cinnamon powder at 250 mg/kg feed. It was observed that the economics of broiler production depended on whether cinnamon was used alone or in combination with essential oils in the feed. According to Metwally (2023), the use of cinnamon (4 g/kg feed) in the diet of Japanese quail increased the net profit per bird compared to the control group. Feed supplements of 2.0% cinnamon and 1.0% ginger can be used as growth promoters to increase profit per bird (Gaikwad et al., 2019). In addition, Omar et al. (2020) showed that chicks fed essential oils had the highest economic and relative efficiency compared to the control group. Recently, Hussein and El-Kassas (2023) found that the use of mixtures of cinnamon, clove, and peppermint oils at a dosage of 0.1 g/kg feed was more beneficial in terms of performance and economic efficiency than the use of cinnamon oils alone at a dosage of 0.3 g/kg feed, with no negative effects on health.

5. Conclusions

Live weight, feed conversion, and good viability had a favorable effect on European production efficiency factors and total yields ($). As a result, it was found that cinnamon at a dosage of 2 g/kg feed as a growth promoter was the most efficient, effective, and reasonably inexpensive herbal feed additive compared to other cinnamon groups.

Highlights

(1) Cinnamon bark powder (CBP) at a dose of 2 g/kg had the highest production efficiency factors and body weight gain (BWG) and had the lowest feed conversion ratio (FCR).

(2) The improvements in weight and thickness of the duodenum, ileum, and entire small intestine persisted up to 4 g CBP/kg diet.

(3) The decrease in pH accelerated significantly the CBP content in the diet^.−1

(4) From an economic perspective, birds fed 2 g/kg CBP had a higher profitability ratio and lower feed cost/kg live weight than the other groups treated with cinnamon.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The results and analyses of this study are freely available upon request.

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/23311932.2023.2284686

Additional information

Funding

The work was supported by the This research was funded by the Researchers Supporting Project, number (RSPD2023R581), King Saud University, Riyadh, Saudi Arabia. [RSPD2023R581].