Production performance and egg quality of Isa Brown chickens fed diets supplemented with carrot peel powder

Nguyen Tuyet Giang^1,2, Le Thi Thuy Hang^1,2, Phan Phuong Loan^1,2 and Le Thi Thuy Loan^1,2

¹ An Giang University, An Giang, Vietnam
² Vietnam National University Ho Chi Minh City, Vietnam
ntgiang@agu.edu.vn

Abstract

The objective of this study was to evaluate the productive performance and egg quality of the Isa Brown chickens fed diets supplemented with carrot peel powder. A total of 120 laying hens at 23 weeks of age were distributed in a completely randomized design with four treatments and ten replicates. The four treatments were CR0, CR0.5, CR1.0 and CR1.5, corresponding to four levels of carrot peel powder supplemented in the diet (0, 0.5, 1.0 and 1.5%). The results showed that the supplementation of carrot peel powder did not affect the body weight and feed intake (p>0.05), but improved the laying rate, feed conversion ratio, egg weight and egg shell thickness (p<0.05) of the chickens. Adding the carrot peel powder had a favorable effect on pigment enrichment of egg yolk. In conclusion, dietary inclusion of 1.5% carrot peel powder was most effective in improving the egg quality without negative impacts on the hen performance. These findings support the application of carrot waste as a potential feed additive for laying hens.

Keywords: Isa Brown chickens, carrot peel powder, carotenoids, egg yolk colour, production performance

Introduction

Table egg is a high-quality protein source in human diet which is high in protein and low in calories, providing 75 kcal per egg. It is considered as a complete food with high digestibility and balanced amino acid profile. In addition, consuming egg does not suffer from any prohibitions of most religions. These features make egg a basic food product widely consumed all over the world (Gautron et al 2022). Among egg compositions, egg yolk colour is one of the most important attributes for consumers’ judge as most them desire the yellow-orange egg yolk than off-white yolk (Milovanovic et al 2021). Egg yolk, as a large source of carotenoids, significantly boost the nutritional value of the human diets, by increasing the total carotenoids content but lowering the cholesterol and triglycerides concentrations (Englmaierová et al 2014; Dansou et al 2023). There are more than 600 carotenoids found in nature, which are classified into two groups: carotenes and xanthophylls, based on their diverse chemical structures and bioavailability.

Carotenoids are associated with provitamin A activity and other health benefits including protecting the eyes from the UV radiation damage, cancer prevention and relieve bone health (Crupi et al 2023; Gao and Zhao 2023). Animal body can not synthesize carotenoids, therefore supplementation of carotenoids is recommended for all poultry species to fascinate the pigmentation, oxidative stability and quality of their products. For laying hens, daily supplementation of carotenoids not only improves the health and production performance but also enhances the egg quality (Marounek and Pebriansyah 2018; Nabi et al 2020). Carotenoids used for egg enrichment often exist in either natural sources or synthetic products. As a phytonutrient, carotenoids are tetraterpene pigments obtained widely from plants via leaves, flowers, fruits, fruit peels and photosynthetic microorganisms such as algae, fungi and cyanobacteria (Victoria-Campos et al 2023; Sharma et al 2024).

Carrot (Daucus carota L.), belonging to the family Apiaceae, is among the most important root vegetables cultivated worldwide. This vegetable has gained in popularity due to the high contents of dietary fiber, minerals, vitamins, carbohydrates and natural bioactive compounds including carotenoids and flavonoids (Raees-ul and Prasad 2015; Ahmad et al 2019; Thiviya et al 2021). The increasing production of carrot varieties also lead to the abundant amount of rejected portions from the food processing industry. The carrot peels, making up 14.19% by fresh weight, is usually discarded, causing contamination in landfills or water sources and creating negative impacts on the environment (Nguyen and Nguyen 2015; Seregelj et al 2021). However, this waste still contains large amounts of natural antioxidants, which are linked with multiple health-promoting properties. The level of total phenolics in carrot peels is 11 times higher than the level obtained in the flesh root, showing an enormous potential in DPPH radical scavenging activity and reducing antioxidant power (Nguyen and Scarlett 2016; Wanna 2019). Therefore, carrot peels with high functional properties could be considered for value-added utilization in poultry industry to reduce the overall production cost and environmental concerns.

To our knowledge, there is no studies investigating the implications of diets enriched with carrot peel powder. In this context, the aim of this work was to investigate the effect of diets supplemented with carrot peel powder on the production performance, egg quality and egg yolk colour of laying hens.

Materials and methods

Preparation of carrot peel powder

The fresh carrot peels (Photo 1A) were collected from the kitchens and canteens of semi-boarding schools in Long Xuyen city, An Giang province, Vietnam. The peels were pre-treated by soaking in a NaCl 5% solution for 2 min, followed by blanching in hot water (90^oC) for 5 minutes. Then, the treated peels were drained for 30 minutes to remove excess water and dried at 50°C for 6 hours under hot-air conditions in a forced convection oven. After drying, the dried peels were milled to powder (Photo 1B) using a grinder equipped with a 300 μm sieve. The powder was packed in polyethylene bags and kept under cold conditions before use. The chemical composition of the carrot peel powder was 90.3% dry matter, 7.41% crude protein, 6.18% ash, 1.79% ether extract and 7.82% crude fiber.

Photo 1. Fresh carrot peels (A) and carrot peel powder (B)

Experimental design and procedure

The experiment was carried out at a private farm in Tri Ton district, An Giang province, Viet Nam, from April to June 2024. A total of 120 Isa Brown hens were randomly assigned into four groups, with ten replicates of 30 birds each. The experimental period of 56 days started at the hen age of 23 weeks. The birds were provided a control diet (0% carrot peel powder) or 0.5%, 0.1% and 1.5% of carrot peel powder as supplementation which were equivalent to the four treatments: CR0, CR0.5, CR1.0 and CR1.5.

All diets were formulated to meet recommendations for laying hens (NRC, 1994), as shown in Table 1. The feed was administrated once daily at 08:00 and water was available at all times. Birds were housed in the batteries (50 cm × 50 cm × 40 cm, with a floor slope of 10◦) All cages were equipped with individual feeders and drinkers to enable ad libitum intake. The average temperature was 26 ± 2°C in the bird house during the experimental period. The light regimen of 16 h light/8 h darkness time was applied throughout the experiment.

Determination of production performance and egg quality parameters

At 23 weeks of hen age, data collection of production performance of the hens commenced and lasted for 56 days, until 31 weeks of hen age. Body weight (BW) of the hens was taken at 23 (initial BW) and 31 (final BW) weeks of age and changes in BW were calculated as the difference between initial and final values. During the experiment, eggs were picked up daily at 16:00 pm. The laying rate and feed intake was recorded weekly. The feed conversion ratio was calculated as the ratio of feed intake to egg mass.

Bi-weekly, 10 eggs were randomly selected in each treatment for assessment of egg quality. Prior to breaking, individual egg was weighed using an electronic scale, while egg height and width were measured using an electronic Vernier caliper to calculate the shape index. For internal quality testing, eggs were broken out onto a flat, shell thickness was measured using a digital thickness caliper and was taken as the mean value at three points at the two ends and the middle positions of the egg. The ratio of egg yolk height to egg yolk diameter was egg yolk index. The Haugh unit was derived using the formula: 100 × log ₁₀ (h - 1.7 × w ^0.37 + 7.6), where h was albumen height (mm) and w was egg weight (g). Other parameters were yolk proportion, albumen proportion, albumen: egg yolk and albumen index.

Egg yolk colour was analyzed with the Minolta Chroma Meter CR-400 (Minolta Co. Ltd., Osaka, Japan), using the CIE (Commission Internationale d’clairage) Lab scale. The L^*, a^* and b ^*values reflect the brightness (0 = black, 100 = white), redness (-a^*= green, a^*= red), and yellowness (-b^*= blue, b^*= yellow), respectively. In advance of the colour measurements, the instrument was calibrated against the CIE standard illuminant D65 with Y = 93.5, x = 0.31 and y = 0.33.

Statistical analysis

All analyses were performed with repetitions. The descriptive statistics including means and standard errors of the means (SEM) were analyzed using the generalized linear model (GLM) procedure of Minitab 16. Differences among the treatments were regarded as significant at minimum 95% level ( p ≤ 0.05).

Results and discussion

Production performance

During the experimental period, there was no mortality or disease observed among the treatments. The weekly means of hen performance traits are shown in Table 2. There was no difference (p>0.05) in the body weight and the feed intake of the chickens among the experimental groups. Average feed intake in this study was in the range of 106-110 g/bird/day, similar to the results of Englmaierová et al (2013) in the Isa Brown hens aged 25-39 weeks, fed diets supplemented with lutein, spray-dried Chlorella, and synthetic carotenoids. However, the inclusion of the carrot peel powder significantly increased the laying rate and improved the feed conversion ratio (p<0.05) of the chickens.

The hens fed diet supplemented with 1.5% carrot peel powder had higher laying rate than the hens fed the other diets (p<0.05). Likewise, feed conversion ratio recorded differences among the treatments. Hens fed diets supplemented with 1% (CR1.0) and 1.5% (CR1.5) carrot peel powder had significantly lower feed conversion ratio than those fed conventional diet (CR0) and diet with 0.5% carrot peel powder (CR0.5). In previous studies, Panaite et al (2021) reported that there was no significant difference in the final body weight, the laying rate and the total number of eggs produced in experimental period, among the diet supplemented with (1) 6% linseed meal and 2% dried kapia pepper; (2) diets supplemented with 6% linseed meal and 2% dried sea buckthorn pomace; and (3) diets supplemented with 6% linseed meal and 2% dried carrot.

In the current study, dietary treatments with carrot peel powder did not negatively impact the hen livability and egg production, making carrot peel powder a viable option to use as good feed supplementation. Similar findings have been reported when natural sources of carotenoids were added to the layer hens (Wang et al. 2022; Nguyen et al 2023) and quails (Valentim et al 2020; Sarmiento‑Garcia et al 2023) diets.

Egg quality

Table 3 shows the external and internal parameters of the egg quality recorded during the experiment. There was no difference (p>0.05) among the treatments in the proportions of egg yolk and albumen, the ratio of albumen to egg yolk as well as the indices of these two components and the overall egg shape. The diets significantly affected (p<0.05) the egg weight, shell thickness, shell proportion, and the Haugh unit. The highest egg weight was recorded in the treatment CR1.5 (55.2 g), followed by CR1.0 (54.0 g), CR0.5 (52.7 g) and CR0 (51.2 g). Egg shell thickness and egg shell proportion were different among the diets (p<0.05). The highest egg shell thickness was recorded in groups supplemented with 1.0% and 1.5% carrot peel powder. The Haugh unit was also affected by experimental diets (p<0.05), being lowest in the group fed the control diet (CR0).

Figure 1 shows that the egg weight increased with the levels of carrot peel powder in the hen ration. According to Ahmadi and Rahimi (2011), higher egg weight and good quality are important to economic viability of the layer chicken industry. Dansou et al (2023) also reported that there was a relationship between the egg weight and the intake of carotenoids in the diet, in which the carotenoids improved hepatic lipid metabolism, regulated the synthesis of specific fatty acids contributing to the increase of egg yolk weight and the whole egg, eventually. Another explanation may be that the structural matrixes of the carotenoids imbedded other nutrients, which in turns increased the overall egg weight.

Figure 1. Effect of supplementation of carrot peel powder on the egg weight

Egg yolk colour is one the most important attributes in consumer perception of egg quality, along with other characteristics such as shell colour, taste and appearance (Rondoni et al 2020). The results showed that adding carrot peel powder to the chicken diet significantly enhanced the colour of egg yolk (p<0.05), as seen in Table 4, Figure 2 and Photo 2.

Egg yolks from hens fed diets supplemented with 1.5% carrot peel powder showed lowest lightness value (L^*= 74.8) and highest redness (a ^* = 3.80) and yellowness (b^* = 40.8) values. The treatment CR0.5 (0.5% carrot peel powder) achieved highest lightness value (L^* = 80.0) and lowest redness value (a^* = 2.29), similar to what found in control treatment (CR0, without carrot peel powder), indicating low bioavailability of carotenoids as a pigment for egg yolk.

Figure 2 ffect of supplementation of carrot peel powder on the b* value (yellowness) of the egg yolk colour

As can be seen in Figure 2, the b^* value of the egg yolk was linearly affected (p<0.05) by the experimental diets. A positive trend was observed in which the levels of carrot peel powder increased the yellowness of egg yolk, to reach a maximum b^* value (40.8) when birds were fed the diet with 1.5% carrot peel powder. The improvement of egg yolk colour in the treatments supplemented with carrot peel powder may associate with the increased levels of carotenoids in the diet, similar to findings of Panaite et al (2021). As noted by Englmaierová et al (2013), the intensity and colour of the egg yolk could be controlled by the type and level of dietary carotenoids. The carotenoids deposition in the egg yolk depends on their polarity, which is lower in nonpolar carotenes than in xanthophylls. Results of the present study confirm previous findings of the high pigmentating ability of carrot (Hammershøj et al. 2010; Spasevski et al 2018; de Souza et al 2019; Panaite et al 2021). Due to the rich carotenoid content, carrot could be used as a suitable alternative to synthetic pigments in egg yolk production.

Photo 2.Varied egg yolk colours among the treatments (CR0: Control, 0% carrot peel powder; CR0.5: 0.5% carrot peel powder; CR1.0: 1% carrot peel powder; CR1.5: 1.5% carrot peel powder)

Conclusions

These results showed that the supplementation with carrot peel powder in the ration improved the laying rate, feed conversion ratio, egg weight and egg shell thickness of Isa Brown chickens. Adding the carrot peel powder at a level of 1.5% increased the yellowness and redness of the egg yolk colour.

Acknowledgments

ike to acknowledge An Giang University (AGU), Vietnam National University Ho Chi Minh City (VNU-HCM) for the research funding (grant No. C2023-16-09). The support from our staffs and students is gratefully acknowledged.

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