Research Article

Effect of Thymus vulgmus Addition to the Diet of Laying Hens on Egg Production, Egg Quality, Biochemical and Antioxidant Parameters

Arkan B. Mohammed*, Ammar S. Abdulwahid, Samah M. Raouf

Department of Animal Production, College of Agriculture, Tikrit University, 34001, Iraq.

Received | September 21, 2021; Accepted | December 04, 2021; Published | January 10, 2022

*Correspondence | Arkan Mohammed, Department of Animal Production, College of Agriculture, Tikrit University, 34001, Iraq; Email: dr.arkanmohammed@tu.edu.iq

Citation | Mohammed AB, Abdulwahid AS, Raouf SM (2022). Effect of Thymus vulgmus addition to the diet of laying hens on egg production, egg quality, biochemical and antioxidant parameters.

Adv. Anim. Vet. Sci. 10(2): 427-433.

DOI | http://dx.doi.org/10.17582/journal.aavs/2022/10.2.427.433

ISSN (Online) | 2307-8316

 

Introduction

In Iraq, commercial breeders of laying hens have a goal of increasing the number of eggs produced per unit of time. Nutrition is vital issue for the optimal care and handling of poultry as a has direct impact on egg production and poultry health (Dilawar et al., 2021). Antibiotic-free diets are the most important factor in the laying hen industry due to the increasing customers interest in antibiotic-free products, this led to an intensification in research for the development of effective antibiotic alternatives. This resulted in the appearance of plant-based feed additives that can be used to improve the growth, quality and health of poultry. Medicinal plants are considered to be a suitable antimicrobial alternative (Bozkurt et al., 2016).

Previous studies showed that the active components of medicinal plants can improve poultry health and growth. It has also been discovered that using plant-based compounds in poultry diets increases productivity and immunity (Harrington et al., 2019). Thyme (Thymus vulgaris) is a versatile herb belongs to Lamiaceae family, used in both fresh and dried forms for various purposes, and its essential oil is extracted and mixed with those of other aromatic herbs. The chemical composition of thyme is 40% thymol and 15% carvacrol (Mikaili, 2010). The essential oils from rosemary, oregano, and thyme have been found to improve egg production of laying hens (Cimrin, 2019). It has been also reported that thyme have a good antimicrobial and antioxidant activities. These biological properties are also known to improve chicken health (Alagawany and Abd El-Hack, 2015). Thymol is a positive allosteric modulator that can stimulate the activity of GABA receptors (García et al., 2006). It can also be used as a drug to reduce pain (Bhandari and Kabra, 2014). The consumption of a combination of thyme, mint, and rosemary can improve the productivity and health of hens. It can also decrease malondialdehyde, increase glutathione (GSH) in the liver, and increase superoxide dismutase (SOD) activity (Abd El-Hack and Alagawany, 2015). Extracts from such aromatic plants were added also to the hen’s diet to enhance their antioxidant levels (Świątkiewicz et al., 2018). Bölükbaşi and Erhan (2007) and Abdel-Wareth (2016) have shown that thyme additives improve egg-quality and performance of hens. Although some studies haven’t found a significant impact of various herb supplementation on egg -production (Arpášová et al., 2014; Ding et al., 2017).

Hence, further studies are required to resolve these discrepancies. This investigation was to evaluate the usefulness of thyme addition to laying hens’ diet on productivity, egg quality, biochemical and antioxidant parameters.

MATERIALS AND METHODS

Birds and experimental design

This research project was conducted at the laying hen farm within the Department of Animal Production at Tikrit University’s, College of Agriculture, following guidelines for the use of animal that were approved by the Institutional Animal-Ethic Committee (No.AS-3002P).

One hundred and eighty Hy-line Brown hens, 40 weeks old were randomly allocated in 9 groups (20 hens, each), where three groups were assigned to each of the three different feeding treatments that was applied from 40 to 47 weeks of age. Hens were fed ad libitum a commercial layer diet (NRC, 1994) consists of Me (kcal kg-1) 2800, Crude protein (15.77%) and Calcium (3.58%), the diet composition are shown in Table 1. The treatments diet was, (T1) Control treatment; (T2) 5 g/kg of thyme powder and (T3)10 g/kg of thyme powder.

Egg production and quality

The hen egg production (HD%) was measured for each treatment and cumulative egg production on weekly basis was also calculated during the period from 40-47 weeks of age. The average egg weight was multiplied by the HD% rate to calculate the egg mass. By dividing the feed intake on the egg mass, the feed conversion ratio (FCR) was calculated. Six eggs were randomly chosen from each group (a total of eighteen per treatment) for measurement of egg quality and was assessed on the inside and outside at day 56. An electronic scale was used to weight the eggs, and a strength tester to measure the eggshells after broken the eggs carefully on a plate (glass). The egg’s yolk was separated from the albumin. Yolk and albumin weight was determined by an electronic scale. Yolk height was measured by a vernier calliper. A Haugh unit (HU) was calculated using egg white protein (albumin) measurements, and the eggshell thickness using a digital micrometer, as described by Haugh (North, 1984). The width of the egg was divided on the egg length to get the index of the egg shape.

 

Table 1: Component’s composition of laying hens’ diet.

Components	%
Corn	40.5
Wheat	30
Soybean meal	17.85
Premixa	2.5
Oil	0.55
Oyster shell	8.6
	100
ME (kcal kg-1)	2800
Crude Protein (%)	15.77
P available (%)	0.50
Lys. (%)	0.76
Meth. (%)	0.40
Methionine + cysteine (%)	0.66
Ca (%)	3.58

a The Premix (1 kilogram of Premix): vit. E, 500 IU; vit. B12, 0.06 mg; vit. B1, 67 mg; vit. A, 334000 IU; vit. D3, 67000 IU; vit. B2, 1000 mg; vit. B6, 0.66 mg; folic acid, 17 mg; choline, 17000 mg; N., 1000 mg; Mg, 3.334 mg; Zinc, 334 mg; Iron, 1.667 mg; Cop., 10 mg; I, 17 mg; Meth., 27000 mg; Phosphor, 10.6% and Se, 0.20 mg.

 

Blood sampling

Nine birds from each group (three hens each replicate) were randomly selected at day 56 (end of the experiment). A blood sample was collected from the wing vein of the hens into two separate vials (5 mL each). The first vial contained heparin to help determine hematological parameters and separate the plasma, while the second did not contain any anticoagulant to obtain serum. The samples were centrifuged at 4000 rpm for 10 min, plasma and serum were separated and stored at –20 °C until analysis.

Hematological parameters

Red blood cell (RBC) and white blood cell (WBC) counts were measured according to (Natt and Herrick, 1952). The packed cell volume (PCV) was determined according to (Dacie and Lewis, 1975).

Biochemical and antioxidants parameters

Serum cholesterol level was calorimetrically determined according to (Kattermann, 1979), and the plasma triglyceride level was determined by the enzymatic method (Sigma Diagnostics Kit No. 339). Also, plasma samples were analyzed for total protein by the Biuret method according to (Yousef and El-Demerdash, 2006); and Albumin concentration calorimetrically according to (Doumas et al., 1971), Globulin concentration was estimated by separation of albumin from total protein. Glucose was estimated in the serum by an enzymatic method (Biosystems SA Kit, No. REF11533). To estimate liver function, ALT and AST activity was calorimetrically determined according to (White et al., 1970). GSH glutathione peroxidase activity (Günzler et al., 1974) and the malondialdehyde concentration were determined according to (Romero et al., 1998).

Statistical analysis

Data were analyzed by one-way ANOVA using the statistical program SAS (Ver. 9.0). Duncan’s test was employed for multiple comparisons. p < 0.05 were used to identify key differences between the treatments.

RESULTS AND DISCUSSION

Egg production

The egg production data of laying hens were given in Table 2. A significant increase was observed in hen egg production (HD%), egg mass, cumulative egg number and egg weight in thyme-treated when compared to control hens throughout the period from 40-47 weeks of age and as overall. Also, a significant (p < 0.05) improved was found in the FCR of the thyme-treated hens during the experimental period.

Egg quality

Table 3 showed that there was no significant effect for thyme addition on most of measured parameters of egg quality (p > 0.05), except for the increase in albumin index (%) and eggshell index (%).

Hematological parameters

The hematological results were summarized in Table 4. There was no significant (p > 0.05) difference in RBC values in treatments. However, PCV (%) showed a significant increase in the T3 hens compared with control. The WBC count significantly increased in response to both thyme treatment in contrast with the control.

Biochemical serum parameters

Figure 1 showed the serum biochemical parameters. Figure 1a showed that thyme-treated hens had non-significant difference in serum glucose level (p>0.05) between treatments. The albumin and total protein levels showed no difference among all treatments (p>0.05) (Figure 1b, c). However, the hens in the thyme treatments showed improved globulin values (Figure 1d).

 

Lipid profile

The effects of thyme additives on the hen lipid profile and liver function were presented in Table 5. Throughout the 56-day study period, plasma triglyceride concentration was not significantly affected by thyme powder treatment. The thyme treatment decreased significantly (p < 0.05) the serum cholesterol concentration. The thyme-treated hens showed the lowest ALT and AST activity compared with the control hens throughout the 56-day study period.

Antioxidant parameters

Figure 2a showed a significant increase (p < 0.05) in the GSH (nmol/mL) levels in the thyme-treated hens compared with the control hens. However, the thyme-treated hens had lower MDA (nmol/mL) levels than the control hens (Figure 2b).

 

Table 2: Influence of thyme powder (Thymus vulgaris) on the productivity of hens from (40-47 weeks) of age.

Treatments	Parameters
	HD (%)	FCR	Cumulative egg number	Egg weight (g)	Egg Mass (g/h/d)
Week 40
T1 (Control)	94.64 ± 0.35a	2.81 ± 0.01a	6.62 ± 0.02a	55.67 ± 0.52a	52.69 ± 0.30a
T2 (5g.kg)	95.71 ± 0.71a	1.97 ± 0.01b	6.70 ± 0.05a	60.92 ± 0.07a	58.31 ± 0.50a
T3 (10g.kg)	95.71 ± 1.42a	1.97 ± 0.02b	6.70 ± 0.12a	61.08 ± 0.53a	58.46 ± 0.58a
Week 41
T1 (Control)	88.92 ± 3.21b	2.28 ± 0.09 a	6.22 ± 0.22a	56.83 ± 0.23b	50.53 ± 2.03b
T2 (5g.kg)	95.36 ± 2.50a	1.92 ± 0.05b	6.67 ± 0.17a	62.84 ± 0.04a	59.92 ± 1.53a
T3 (10g.kg)	96.42 ± 0.71a	1.95 ± 0.04b	6.75 ± 0.05a	61.10 ± 0.86a	58.91 ± 1.27a
Week 42
T1 (Control)	92.14 ± 2.85b	2.17 ± 0.06a	6.45 ± 0.20a	57.34 ± 0.06b	52.83 ± 1.58b
T2 (5g.kg)	95.35 ± 3.21a	1.86 ± 0.05b	6.67 ± 0.22a	64.81 ± 0.51a	61.78 ± 1.59ab
T3 (10g.kg)	93.57 ± 1.43a	1.98 ± 0.02b	6.55 ± 0.10a	61.97 ± 0.25a	57.99 ± 0.65a
Week 43
T1 (Control)	90.71 ± 3.57b	2.10 ± 0.09a	6.35 ± 0.25b	60.37 ± 0.20a	54.77 ± 2.34b
T2 (5g.kg)	92.86 ± 1.43a	1.90 ± 0.02b	6.50 ± 0.10a	65.20 ± 0.30a	60.54 ± 0.65a
T3 (10g.kg)	91.78 ±1.07a	1.95 ± 0.04b	6.42 ± 0.07a	64.11 ±0.72a	58.85 ± 1.35a
Week 44
T1 (Control)	87.86 ± 3.57b	2.15 ± 0.05a	6.15 ± 0.10a	60.84 ± 0.44b	53.46 ± 1.26b
T2 (5g.kg)	90.71 ± 1.42a	1.93 ± 0.01b	6.35 ± 0.10 a	65.55 ± 0.40a	59.46 ± 0.57a
T3 (10g.kg)	91.78 ± 1.07a	1.95 ± 0.04b	6.42 ± 0.12a	64.30 ± 0.15a	59.01 ± 1.28a
Week 45
T1 (Control)	78.93 ± 1.07b	2.39 ± 0.01a	5.52 ± 0.07b	60.92 ± 0.12b	48.09 ± 0.75b
T2 (5g.kg)	89.64 ± 1.78 a	1.94 ± 0.04b	6.27 ± 0.12a	65.95 ± 0.10 a	59.12 ± 1.26a
T3 (10g.kg)	90.35 ± 0.35a	1.94 ± 0.05b	6.32 ± 0.02a	65.56 ± 0.46a	59.23 ± 0.19a
Week 46
T1 (Control)	76.43 ± 2.14b	2.44 ± 0.07a	5.35 ± 0.12b	61.77 ± 0.07b	47.22 ± 1.38b
T2 (5g.kg)	90.35 ± 0.35a	1.90 ± 0.01b	6.32 ± 0.25a	66.83 ± 0.65a	60.38 ± 0.35a
T3 (10g.kg)	92.14 ± 1.43a	1.87 ± 0.03b	6.45 ± 0.10a	66.84 ± 0.08a	61.59 ± 1.03a
Week 47
T1 (Control)	80.00 ± 0.71b	2.34 ± 0.03a	5.60 ± 0.05b	61.37 ± 0.18b	49.10 ± 0.58b
T2 (5g.kg)	92.85 ± 0.71a	1.82 ± 0.02b	6.50 ± 0.02a	68.22 ± 0.37a	63.35 ± 0.14a
T3 (10g.kg)	91.42 ± 0.71a	1.86 ± 0.02b	6.40 ± 0.05a	67.81 ± 0.43a	61.99 ± 0.08a
Week 40-47
T1 (Control)	86.20 ± 1.38b	2.25 ± 0.04a	48.27 ± 0.77b	59.39 ± 0.06b	51.19 ± 0.88b
T2 (5g.kg)	92.86 ± 1.07a	1.90 ± 0.01b	52.00 ± 0.05a	65.04 ± 0.29a	60.39 ± 0.42a
T3 (10g.kg)	92.90 ± 0.18a	1.93 ± 0.05b	52.05 ± 0.10a	64.10 ± 0.09a	59.55 ± 0.03a

Means with different letters in the same column indicate a significant difference level (p<0.05).

 

Table 3: Influence of thyme powder (Thymus vulgaris) on egg quality of hens (56 days).

Parameters	Treatments
	T1 (Control)	T2 (5 g/Kg)	T3 (10 g/Kg)
Haugh unit	82.09 ± 3.04a	86.18 ± 1.17a	85.87 ± 1.12a
Yolk weight (g)	28.03 ± 1.18a	26.59 ± 0.75a	28.32 ± 2.01a
Albumin weight (g)	59.73 ± 0.98a	59.02 ± 1.06a	58.83 ± 1.85a
Eggshell weight (g)	12.24 ± 0.82a	12.39 ± 0.42a	12.85 ± 0.48a
Albumin index (%)	0.084 ± 0.006b	0.101 ± 0.005a	0.097 ± 0.001ab
Yolk index (%)	0.449 ± 0.009a	0.483 ± 0.022a	0.446 ± 0.021a
Eggshell index (%)	78.85 ± 0.87b	82.01 ± 0.61a	77.19 ± 0.41ab
Eggshell with member	0.345 ± 0.008a	0.390 ± 0.004a	0.360 ± 0.006a

Means with different letters in the same column indicate a significant difference level (p<0.05).

 

Table 4: Influence of thyme powder (Thymus vulgaris) on PCV (%), RBC (106 cells/mm3), and WBC (106 cells/mm3) of hens (56 days).

Parameters	Treatments
	T1 (Control)	T2 (5 g/kg)	T3 (10 g/kg)
PCV (%)	30.33 ± 1.58b	30.33 ± 2.57b	32.16 ± 2.57a
RBC (106 cells/mm3)	2.64 ± 0.20a	2.50 ± 0.06a	2.57 ± 0.12a
WBC (106 cells/mm3)	22.77 ± 1.22b	25.41 ± 0.79a	25.41 ± 1.39a

Means with different letters in the same column indicate a significant difference level (p<0.05).

 

Table 5: Effect of thyme powder (Thymus vulgaris) on lipid profiles and liver function of hens (56 days).

Parameters	Treatments
	T1 (Control)	T2 (5 g.kg)	T3 (10 g.kg)
Cholesterol (mg/dL)	150.33 ± 2.12a	147.00 ± 1.48b	130.35 ± 1.34b
Triglycerides (mg/dL)	169.83 ± 6.55a	166.5 ± 6.50a	164.00 ± 6.39a
ALT (I/U)	41.66 ± 0.28a	40.50 ± 0.49b	40.83 ± 0.46b
AST (I/U)	91.00 ± 1.22a	73.83 ± 1.47b	80.16 ± 1.35b

Means with different letters in the same column indicate a significant difference level (p<0.05).

 

Recently, several studies have discovered that aromatic plants have a beneficial effect on animal production and physiology. Specifically, there is an increase in digestive enzyme secretion and improvements in immunity response and the gut flora population. This study evaluated the possible effects of supplementing laying hens with thyme powder in their diet on egg production, hematological, biochemical and some antioxidant parameters. Thyme treatments led to a significant improvement in the productive parameters in terms of an increase in egg number and mass and also improved feed conversion ratio when compared with the control. Some previous studies have shown that thyme powder or extracts improve egg production parameters (Abd El-Hack and Alagawany, 2015; Abdel-Wareth, 2016). Aydogan et al. (2020) showed that essential oils produced from medicinal plants can be successfully used as growth promoters in laying hens because their aromatic properties increase feed intake, and that herbs, such as thyme, black cumin seeds, green tea, garlic, neem. Their essential oils, can potentially be used as an alternative to antibiotics and growth promoters. In this study, the significant effect on egg production (%), egg mass, and feed conversion could be attributed to the improvement in digestion and nutrient absorption and the overall health of the digestive system (Shahryar et al., 2011). The active ingredients in thyme enhance the digestive enzymes, such as amylase, protease, and lipase, resulting in better nutrient digestibility and enhanced egg production. In contrast, Ding et al. (2017) did not find any significant difference in egg production or egg mass when hens were fed thyme. In this study, a significant increase in the packed cell volume (PCV %), and the white blood cells (WBC) count when using thyme treatment. Serum cholesterol levels were also lower in the thyme-treated hens when compared with the control hens. Serum cholesterol levels were consistent with those of Mansoub (2015). Hashemipour et al. (2013) found thyme to have a significant positive impact on the lipid profile, and our findings also show that thyme enhances the serum lipid parameters and it is agreed with (Abd El-Hack and Alagawany, 2015).

Thyme additives in the diet of laying hens also significantly (p < 0.05) increases glutathione peroxidase activity, while decrease malondialdehyde concentration, and ALT and AST activity. Ashour et al. (2014) found that consuming herbs or their extracts leads to an increase in some antioxidant enzymes, such as glutathione peroxidase (GSH), as well as a decrease in the malondialdehyde (MDA) level. As a result, increased levels of glutathione peroxidase may help maintain the antioxidant system in a constant state in laying hens and the biological effects of antioxidant activity should benefit the health of chickens. The presence of phenolic hydroxy treatments, which act as hydrogen donors to the proxy radicals produced in the first stage of lipid oxidation, is believed to be responsible for thyme’s high biological activity as a natural antioxidant (Hashemipour et al., 2013). Paraskevopoulou et al. (1997) found that adding thyme in hens’ diet prevents lipid oxidation in eggs kept in the refrigerator. Based on this study findings, it can be concluded that using thyme as a phytogenic feed additive can improve the nutritional and economic aspects of poultry breeding in the future. The current study results are in agreement with (Gumus et al., 2017), who found that essential oils in thyme enhances glutathione peroxidase activity and decreases the malondialdehyde concentration in the liver and serum.

Conclusions and Recommendations

Thyme addition to the diet of laying hens improved egg production, egg quality, and feed conversion ratio, along with increasing glutathione peroxidase activity, decreasing cholesterol level, malondialdehyde and ALT and AST activity. Therefore, the addition of 5 and 10 g/kg of thyme is recommended as beneficial supplementation levels for laying hen feed.

Acknowledgments

The authors would like to acknowledge the Department of Animal Production-Tikrit University for providing financial support.

Novelty Statement

This study is to evaluate thyme as an additive because it contains bioactive components such as thymol, carvacrol, linalool, a-terpineol, and 1,8-cineole. Thyme powder is expected to increase egg production, egg quality, and feed conversion ratio in laying hens, while also increasing glutathione peroxidase activity, decreasing cholesterol, and increasing antioxidant responses.

Author’s Contribution

AM was coordinator of the research and analyzed and interpreted the data. AM, AA and SR in the study were supervisor of data collection and wrote draft manuscripts. A and S was assistants of the collection of data.

Conflicts of interest

The authors have declared no conflict of interest.

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