INTRODUCTION
The initial stage of a laying hen's life is crucial for its development. During this period, optimal nutrition is essential for ensuring strong performance and high egg quality throughout the hen's productive lifespan (Rentsch et al., 2023). During this phase, young laying hens undergo significant physiological changes, including the development of reproductive organs and the initiation of egg production. Adequate nutrition during this period is crucial for supporting these physiological processes and laying a foundation for sustained productivity (Bryden et al., 2021).
Recognizing the importance of optimal nutrition for young laying hens, the use of feed additives (plants, by-products, wastes) has gained widespread recognition as valuable supplements to conventional diets (Vlaicu et al., 2023). These additives are included in dietary formulations of poultry with the aim to improve nutrient profile of the diets, promote animals growth, reproductive health, production performances and products quality (Nys, 2017; Wang et al., 2017).
By enhancing the nutrient profile of conventional diets, feed additives aim to fill nutritional gaps and improve overall performance and product quality.
One promising addition to the feed additives portfolio is rosehip (Rosa canina L.) leaves, which offer a wealth of bioactive compounds with potential benefits for laying hen nutrition. Generally, rosehip is rich in polyphenols, flavonoids, vitamins, and minerals, all of which contribute to their reputed antioxidant, anti-inflammatory, and immune-modulating properties (Vlaicu et al., 2022a; Khelfi et al., 2024). Integrating rosehip leaves into the diet of laying hens holds promise for addressing various challenges encountered during the first stage of production, such as help mitigate oxidative stress, which commonly occurs during periods of rapid growth and reproductive development (Righi et al., 2021) while ensuring optimal nutrient absorption and utilization, resilience to infectious diseases, promoting health and welfare (Gessner et al., 2017).
Moreover, incorporating rosehip leaves into the diet of laying hens aligns with the growing interest in natural, plant-based alternatives to synthetic additives. As consumer demand for sustainably sourced and minimally processed products continues to rise, the use of botanical additives like rosehip leaves presents an attractive proposition for poultry producers seeking to enhance the nutritional profile of their eggs while meeting evolving market preferences (Sadowski et al., 2024). However, despite the growing interest in this area, there remains a paucity of comprehensive research examining the different effects of rosehip co-products such as the leaves, over the fruits by-products, which have been already reported as powerful antioxidants in eggs and poultry meat (Aldemir et al., 2021; Grigorova et al., 2021; Vlaicu et al., 2022a).
This study aims to investigate the influence of rosehip (Rosa canina L.) leaves as a feed additive during the first stage of laying hens on performance parameters and various egg quality characteristics. By evaluating the potential benefits of rosehip supplementation, this study aims to contribute insights into optimizing the nutritional management of young laying hens, fostering improved productivity and product quality within the poultry industry.
MATERIALS AND METHODS
Ethical Protocol
All animal care, handling, and sampling procedures adhered to the ethical standards established by the institute's ethical committee, in compliance with Romanian legislation Law 206/2004, and Ordinance 28/31.08.2011, Law 43/11.04.2014, Directive 2010/63/EU. Prior to developing the study, approval was obtained from the Ethical Commission of the National Research and Development Institute for Animal Biology and Nutrition under protocol number 3578/17.07.2023 and followed Romanian guidelines for the care and use of laboratory animals for experimental purposes.
Plant Materials
The fresh rosehip leaves were harvested during May of 2023, from the local spontaneous flora in Balotesti County, Ilfov, Romania (44° 37′ 12.936′′ N and 26° 5′ 11.904 E). After collecting the necessary amount, the fresh leaves were dried in an Eco Cell oven (Blueline Comfort, Nuremberg, Germany) at 65°C, for 24 to 48 h until they were uniformly dried. After that, the dried leaves were milled to powder in a laboratory hammer mill and kept in paper bags at room temperature until used as feed additive in laying hens’ diets.
Experimental Design, Housing, Animals, and Diets
The experiment was developed in the institution research Biobase (Balotesti, Ilfov county, Romania) in a clean and environmentally controlled poultry house.
Before bringing the laying hens the temperature in the experimental hall was set at 18°C to 20°C using a thermostat-controlled heating system. Temperature sensors were placed throughout the experimental hall to monitor any fluctuations with an electronic Viper Touch computer. Air quality parameters (ammonia levels, humidity, and carbon dioxide concentrations) were assessed through ventilation system, as recommended by the breeding guide. The floor of the experimental hall was covered with wood shavings to a depth of 5 cm to provide bedding and absorb moisture. Bedding material was replaced as needed, to maintain cleanliness and hygiene. Nesting boxes (1 box for 3 hens) were provided within the experimental hall to facilitate egg-laying behavior. Each nesting box was filled with straw to provide a comfortable and secluded environment for hens to lay their eggs. The lighting regimen (8 lux) consisted of 14 h of light and 10 h of darkness per day from 17 to 19 wk of age, and after was changed to 16 h of light and 8 h of darkness per day (10 lux).
After the experimental hall was set, 90 Lohmann Brown Classic chicks aged 17 wk (pre-laying phase), were accommodated in identical pens of 3.96 m2, each of them having 30 laying hens/pen (0.132 m2 /hen). From 17 to 19 wk of age, the hens were fed a commercial standard diet (having 17.50% crude protein and 2730 kcal metabolizable energy), designated for this stage of raising, to assure a smooth transition from developer feed (low calcium and low nutrient density) to a diet with high calcium and nutrient levels. After these 2 wk the laying hens weighed an average of 1,579 g and reached 8 to 10% laying rate. To optimize the start of production, the hens, raised under identical conditions, were fed a standard diet from 20 to 23 wk of age (18.50% crude protein and 2770 kcal metabolizable energy), meeting the nutritional requirements recommended for the initial phase of laying, specifically formulated to ensure maximum egg mass, optimal daily feed intake, and laying rate.
After this careful preparation period, the laying hens have been individually weighed (1,752 g average body weight) and prepared for 2 wk (24–25 wk of age) for the actual feeding trial during the first laying stage. All hens were fed the same basal diet, having 17.50% crude protein and 2725 kcal metabolizable energy, as recommended by the management breeding guide of Lohmann Brown. Following the next 6 wk (26–32 wk of age), before reaching peak production the feeding trial was developed to test the effect of feed additives (rosehip leaves) on laying hens’ performance and egg characteristics. For that, the 90 Lohmann Brown Classic laying hens divided into 3 groups of 30 hens/group, were assigned to 3 different diets as follow: a control diet (RL0) without feed additive, and 2 experimental diets containing 0.5% rosehip leaves (RL0.5) and 1% rosehip leaves (RL1), as presented in Table 1.
The laying hens were provided with 15 cm of space per hen at the feeders. Waterers equipped with drinking nipples (3 hens per nipple drinker) were available throughout the experimental hall to ensure convenient and unrestricted access to clean, fresh water for the hens. These waterers were monitored daily to prevent spoilage and contamination.
Table 1. Ingredients of control and experimental diets supplemented with rosehip leaves designed for the first stage of laying hens.
Content per kg diet: vitamin A: 13.500 IU; vitamin D3: 3000 IU; vitamin E: 27 mg; vitamin K3: 2 mg; vitamin B1: 2 mg; vitamin B2: 4.8 mg; pantothenic acid: 14.85 mg; nicotinic acid: 27 mg; vitamin B6: 3 mg; vitamin B7: 0.04 mg; vitamin B9: 1 mg; vitamin B12: 0.018 mg; vitamin C: 25 mg; manganese: 71.9 mg; iron: 60 mg; copper: 6 mg; zinc: 60 mg; cobalt: 0.5 mg; iodine: 1.14 mg; selenium: 0.18 mg. RL0 – control diet; RL0.5 – experimental diet supplemented with 0.5% rosehip leaves; RL1- experimental diet supplemented with 1% rosehip leaves.
Laying Performance and Egg Production
Production performance monitoring and recording were conducted on a daily basis for parameters such as average daily feed intake (ADFI, g/bird/day), feed conversion ratio (FCR, kg feed/ kg eggs), laying rate (%), and egg weight (g). Egg mass was calculated by multiplying the laying rate (%) by the average egg weight (g) divided by 100.
Egg Sampling
After every 2 experimental weeks, when the laying hens were 28, 30, and 32 wk old respectively, 30 eggs from each treatment (n = 90) were collected. This resulted in a total of 270 eggs (90 eggs per time point × 3 time points) submitted for quality analysis. Eggs were collected over a period of 2 consecutive days at each time point, ensuring that all hens were equally represented. During the collection period, eggs were stored at 4°C to maintain their quality until analysis. All collected eggs were evaluated within 24 hours of collection to minimize any potential changes in quality characteristics. The quality analysis included measurements of egg weight and its components, the nutritional composition of albumen and yolk, and the CIE color of both the yolk and albumen. Additionally, the fatty acid profile was evaluated from egg yolks collected only after 6 wk of the feeding trial.
Egg Characteristics Evaluation
The eggs collected every 2 wk, at 28 wk (30 eggs/group), 30 wk (30 eggs/group) and 32 wk (30 eggs/group) of laying hens age were weighed one by one separately using a digital Kern laboratory balance with an accuracy of 0.001 g. After, the eggs were broken, the yolks, albumen, and shells were manually separated and individually weighed to determine the weight evolution of each component. The yolk ratio, albumen ratio and yolk to albumen ratio were determined with the following formulas:
Primary Chemical Analysis
The nutritional composition analyses of compound feeds (at the begging of the experiment) and egg components (at every 2 experimental weeks) were conducted on samples dried at 65°C, following standardized methods defined by the Association Official of Analytical Chemists (AOAC, 2000). Dry matter was determined by the gravimetric method using a Sartorius (Gottingen, Germany) scale and BMT drying oven, ECOCELL Blueline Comfort (Nuremberg, Germany). Crude protein was determined by the Kjeldahl method (Kjeltec auto 1030 Tecator Instruments, Höganäs, Sweden) according to SR EN ISO 5983-2:2009. Crude fat was determined using a Soxhlet apparatus by extraction in organic solvents (Soxtec 2055 Foss Tecator, Höganäs, Sweden) according to SR EN ISO 6492:2001. Crude fiber was determined by the method with intermediary filtration (Fibertec 2010 System Foss Tecator, Höganäs, Sweden) according to SR EN ISO 6865:2002 and the ash content was determined by the gravimetric method using a Caloris CL 1206 furnace.
CIE Lab Color Analyses
The yolk and albumen color were assessed using the CIE-Lab method, where L* (with 100 representing white and 0 representing black) denotes brightness, and a* (indicating redness (a+) if positive and greenness (a-) if negative) and b* (signifying yellowness (b+) if positive and blueness (b-) if negative) represent color parameters. These assessments were conducted using the Konica Minolta Chroma Meter CR-400 device (Holdings Inc., Tokyo, Japan), calibrated with a standard white ceramic reference (illuminate C) and a standardized white non-reflective background for the measurement. Subsequently, 30 eggs per treatment were selected, after 2nd, 4th, and 6th experimental weeks and the yolks and albumens from each 3 eggs were separated and placed in Petri dishes (90 × 15mm) and homogenized with a glass stirring rod to ensure complete mixing without causing air incorporation. The homogenate of each 3 samples (30 measurements per group) was analyzed according to the colorimeter's operating procedures, with readings taken at various spots on the yolk and albumen for lightness (L*), redness (a*), and yellowness (b*) according to the CIE Lab trichromatic system. These readings were automatically utilized to determine the surface color parameters such as ΔL* difference in lightness and darkness (+ = lighter, – = darker); Δa*, difference in red and green (+ = redder, – = greener); Δb*, difference in yellow and blue (+ = yellower, – = bluer) and the color difference ΔE* among the treatments.
Egg Yolk Fatty Acids Analyses
Fatty acid (FA) analyses were conducted on six pooled egg yolk samples (18 egg yolks) from the eggs collected after 6 experimental weeks, (32 wk of laying hens age) then dried at 65°C using fatty acid methyl ester (FAME) gas chromatography, as described by Turcu et al., (2021). A Perkin Elmer-Clarus 500 chromatograph (Waltham, MA) equipped with a flame ionization detector (FID) and featuring a BPX70 capillary column (60 m × 0.25 mm i.d., 0.25 μm film thickness) was employed. FAME identification was achieved by comparing retention times with those of known standards. The average quantity of each fatty acid was utilized to calculate the total saturated (SFA), unsaturated (UFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids.
Statistical Analyses
The experimental data were statistical analyzed as 2 × 2 factorial arrangement using 2-way ANOVA (General Linear Model procedure) followed by Tukey's HSD test. The model included the main effects of rosehip leaves and time, as well as the interaction between them. XLSTAT (Addinsoft, NY) software was used for statistical interpretation and a probability level below 5% was considered significant (p < 0.05).
RESULTS
Nutritional Composition, and Fatty Acids Profile of the Diets.
The results of the analyzed nutritional composition are presented in Table 2.
The dry matter, crude protein, crude fat, and ash had similar values. However, the crude fiber content was higher in the RL0.5 and RL1 diets, compared with RL0, due to the rosehip higher level addition. The sum of fatty acids from the diets showed that RL0.5 diet had higher content of n-6 and n-3 (2.02% and 7.76% higher) than RL0, while the RL1 diet had even higher n-3 (3.57%) and n-6 (6.66%) content compared with RL0. Both experimental diets supplemented with rosehip leaves presented lower n-6/n-3 ratio, compared with control diet.
Table 2. Chemical composition and fatty acids profile of the experimental diets supplemented with rosehip leaves versus control diet.
RL0 – control diet; RL0.5 – experimental diet supplemented with 0.5% rosehip leaves; RL1- experimental diet supplemented with 1% rosehip leaves; SFA - saturated fatty acids; MUFA - monounsaturated fatty acids; PUFA - polyunsaturated fatty acids; UFA – unsaturated fatty acids; n-3 and n-6: represents the sums of each group; n-6/n-3 – the ratio between the total n-6 and total n-3; n=3.
Effect of Rosehip Leaves on Production Performances During First Stage of Laying
In Table 3 are presented the results obtained for production parameters, after 2 wk, 4 wk and 6 wk of feeding laying hens with rosehip leaves, during first stage of laying (28 to 32 wk of hens age). The results showed that hens age had a significant effect (p < 0.05) on ADFI and egg mass parameters, while the effect of rosehip leaves was more pronounced showing significant differences (p < 0.05) between RL0.5 and RL1 for laying rate, FCR and egg mass compared with RL0 group.
Table 3. Effect of rosehip leaves on production performances of laying hens during first stage of laying, compared with control diet.
RL0 – control diet; RL0.5 – experimental diet supplemented with 0.5% rosehip leaves; RL1- experimental diet supplemented with 1% rosehip leaves; RL – rosehip leaves; wk – weeks of age; ADFI – average daily feed intake; FCR – feed conversion ratio; SEM – standard error of the mean; P value – level of significance.
a, b, c, d, and e letters withing each row mean significant differences among the groups.
Effect of Rosehip Leaves on Egg Characteristics During First Stage of Laying
The effect of rosehip leaves on egg characteristics are presented in Table 4. The feed additive tested had a significant effect (p < 0.05) only on yolk/albumen ratio. The effect of hens age was significant (p < 0.05) for egg and yolk weight, as well as on albumen and yolk ratio. The group fed with RL1 diet, having greater values than the RL0 group, especially at 32-wk of hens age.
Table 4. Effect of rosehip leaves on egg characteristics evolution during 6 wk of feeding trial.
RL0 – control diet; RL0.5 – experimental diet supplemented with 0.5% rosehip leaves; RL1- experimental diet supplemented with 1% rosehip leaves; RL – rosehip leaves; wk – weeks of age; SEM – standard error of the mean; P value – level of significance.
a, b, c, d, and e letters withing each row mean significant differences among the groups.
Effect of Rosehip Leaves on Eggs Yolk Color During First Stage of Laying
The effect of rosehip leaves on eggs yolk color was significant, especially for the L* parameter in the RL1 and RL0.5 when compared with RL0 egg yolks. The a*, b* and ΔL* were significantly higher (p < 0.05) only in the egg yolks of RL1 compared with RL0 egg yolks (Table 5). The changes in L*, a*, and b* measurements indicate significant color shifts in the samples over time and with varying RL levels. The increase in L* values suggests that the samples are getting lighter, while the rise in a* and b* values indicate a shift towards more red and yellow tones, respectively. These changes reflect the effect of RL supplement, resulting in noticeable color differences (ΔE*).
Table 5. Effect of rosehip leaves on egg yolk color determined by CIE chromameter.
RL0 – control diet; RL0.5 – experimental diet supplemented with 0.5% rosehip leaves; RL1- experimental diet supplemented with 1% rosehip leaves; wk – weeks of age; The letters L*, a* and b* represent each of the 3 values the CIELAB color space used to measure yolk color and calculate color differences ΔL*. L* represents lightness from black to white on a scale of 0 to 100, while a* and b* represent chromaticity with no specific numeric limits. Negative a* corresponds with green, positive a* corresponds with red, negative b* corresponds with blue and positive b* corresponds with yellow; RL – rosehip leaves; SEM – standard error of the mean; P value – level of significance.
a, b, c, d, and e letters within each row mean significant differences among the groups at P < 0.05.
Effect of Rosehip Leaves on Eggs Albumen Color During First Stage of Laying
In terms of rosehip leaf effect on eggs albumen color, both RL level and hens age, significantly altered the values of L*, a*, b* and the color difference (ΔL*) between the analyzed parameters, as presented in Table 6. The effect of rosehip leaves supplement on RL0.5 and RL1 eggs albumen, had the highest luminosity (L*) when compared with RL0. However, the hens age showed that RL1 luminosity in eggs albumen, was higher than both RL0.5 and RL0, and the RL0.5 significantly higher than RL0 eggs albumen.
Table 6. Effect of rosehip leaves on egg albumen color determined by CIE chromameter.
RL0 – control diet; RL0.5 – experimental diet supplemented with 0.5% rosehip leaves; RL1- experimental diet supplemented with 1% rosehip leaves; wk – weeks of age; The letters L*, a* and b* represent each of the 3 values the CIELAB color space used to measure albumen color and calculate color differences ΔL*. L* represents lightness from black to white on a scale of 0 to 100, while a* and b* represent chromaticity with no specific numeric limits. Negative a* corresponds with green, positive a* corresponds with red, negative b* corresponds with blue and positive b* corresponds with yellow; RL – rosehip leaves; SEM – standard error of the mean; P value – level of significance.
a, b, c, d, and e letters within each row mean significant differences among the groups.
Effect of Rosehip Leaves on Eggs Albumen, Yolk and Shell Primary Chemical Composition During First Stage on Laying
The effect of rosehip leaves on primary chemical composition of eggs albumen, yolk and shell is presented in Table 7. The results revealed that albumen protein was significantly (p < 0.05) increased by the level of additive on RL1 group compared with RL0.5 and RL0, while the hens age, showed that protein increased significantly (p < 0.05) in both groups supplemented with rosehip. In yolks, the fat content was significantly increased (p < 0.05) only in eggs of RL1 group, compared with RL0, while RL0.5 had no significant effect.
Table 7. Chemical composition of eggs albumen, yolk, and shell.
RL0 – control diet; RL0.5 – experimental diet supplemented with 0.5% rosehip leaves; RL1- experimental diet supplemented with 1% rosehip leaves; DM – dry matter; CP – crude protein; EE – crude fat; RL – rosehip leaves; wk – weeks of age; SEM – standard error of the mean; P value – level of significance.
a, b letters within each row, mean significant differences among the groups.
Effect of Rosehip Leaves on Egg Yolk Fatty Acids Profile During First Stage on Laying
No significant effect (p > 0.05) was observed in the profiles of individual fatty acids after 6 wk of administering the experimental diets. However, the influence of rosehip leaves was evident on the main classes of fatty acids, as illustrated in Figure 1.
Figure 1. Effect of rosehip leaves supplementation during the first stage of laying hens, on main fatty acids classes determined in the egg yolk samples. RL0 – control diet; RL0.5 – experimental diet supplemented with 0.5% rosehip leaves; RL1- experimental diet supplemented with 1% rosehip leaves; ns- non significant; ** p < 0.01; *** p < 0.001; **** p < 0.0001.
DISCUSSION
This study investigated the effects of rosehip leaves supplementation as feed additive on the production performance of laying hens during the initial stage of laying. The ADFI parameter, showed no significant difference (p > 0.05) among the groups (RL0%, RL0.5%, and RL1%), as a response to dietary rosehip, however, with the hens age (28, 30, and 32 wk) ADFI significantly increase (p < 0.05), with the highest intake observed at the age of 32 wk old. The lack of significant effect of rosehip leaves in ADFI between the groups suggests that the addition of rosehip leaves did not adversely affect the appetite or feed consumption of the laying hens. This finding is in line with previous research indicating that natural feed additives, used in laying hens (aged 32 to 40 or 80 to 86 wk), such as fennel, black cumin and red pepper, garlic, marigold, fennel seeds, thyme, bilberry and walnut leaves or hot red pepper, at 0.5% to 1% inclusion level, did not disrupt the normal feeding behavior of poultry (Saki et al., 2014; Abou-Elkhair et al., 2018; Pandey et al., 2019; Untea et al., 2020). Corroborating these findings, we consider that the observed increase in ADFI over time may be attributed to factors like increased metabolic demands associated with egg production and maturation of the hens' reproductive systems. Further, the improvement in FCR suggests that hens fed with rosehip leaves utilized their feed more efficiently to produce eggs. This enhanced FCR is likely due to the antioxidant properties of rosehips, which may improve nutrient utilization and metabolic processes in laying hens (Vlaicu et al., 2022a), ultimately leading to better FCR values in both RL1 and RL0.5 groups when compared with RL0 group. The main effect is attributed to rosehip leaves, as time had no effect on FCR parameter. Similarly, Abou-Elkhair et al. (2018), reported a significant decrease of FCR in laying hens fed 0.5% fennel seeds, black cumin seeds, or hot red pepper compared with control diet during peak production (36–40 wk old). However, the same authors reported increased FCR at 6-wk compared with 2-wk of feeding. On the other hand, in the late stage of laying hens, feed additives had no significant effect on FCR (Saki et al., 2014). Laying rate, a crucial indicator of hen productivity, showed notable enhancements with the supplementation of RL. This increase in laying rate was evident in both RL0.5 and RL1, compared to the RL0 group. Similarly, Liu et al. (2023), reported that a mixture of Chinese herbs as feed additives in laying hens aged 28 wk, significantly increased (p < 0.05) egg production. Also, 0.5% pumpkin and garden cress combination, led to significantly higher egg production in Mandarh laying hens aged 24 wk (El-Saadany et al., 2022). On the other hand, Untea et al. (2020) reported no significant effect of 0.5% bilberry leaves or 1% walnut leaves in Tetra SL laying hens, aged 32 wk. The observed rise in laying rate from the current study can be attributed to the beneficial bioactive compounds present in feed additives used as supplement. Although there are no studies regarding the use of rosehip leaves on laying hens diets, generally, natural feed additives have been reported to positively influence productive performance in poultry (Swelum et al., 2021; El-Sabrout et al., 2023).
The egg mass significantly increased with the supplementation of rosehip leaves in the laying hens diet. The both, time, and rosehip level, showed a significant response at the 0.5% and 1% inclusion levels, indicating a dose-dependent response. Higher egg mass in the groups fed with rosehip leaves indicate that the feed additive used con-tributed to achieve higher egg mass without compromising laying intensity. The rise in egg mass can also be attributed to the favorable impact of rosehip leaves on hen health and reproductive performance, potentially through modulation of hormonal balance and enhancement of ovarian function (Titcomb et al., 2019; Mandey and Sompie, 2021). Others have reported that different feed additives enhance birds’ health by maintaining a balanced microflora in the digestive system, leading to more nutrients available for absorption, and better production (Achilonu et al., 2018; Mandey and Sompie, 2021). Although, rosehip leaves can be a novel feed additive in the field of poultry nutrition, com-paring our results with previously published data, on the effectiveness of different feed additives (plants, herbs, leaves) represent a strategy to improve the efficiency in the poultry industry. Further research is warranted to elucidate and to optimize different inclusion levels of rosehip leaves for maximal benefits in laying hen production systems.
Egg weight is an important trait that influences egg quality as well as grading and is determined without breaking the egg. The egg quality characteristics during the first stage of laying, showed that there were no significant differences as influenced by different levels of rosehip leaves. However, eggs collected at 30 and 32 wk of hens age had higher average weight compared to those collected at 28 wk of age. Egg component weights also depend on time and age of laying hens, but only the yolk weight increased significantly, suggesting that during first stage of laying, yolk weight is developing faster, while the albumen and shell have almost reached their constant weight. This effect confirms the finding of Tůmová and Gous (2012) which have reported that the proportion of yolk is negatively related to egg size but positively related to hen age. As recently reported, rosehip meal used in laying hens during peak production (29-wk-old Tetra SL) had no significant impact on egg characteristics (Vlaicu et al., 2022), while raspberry pomace, had a detrimental effect on egg and shell weights as reported by Sosnówka-Czajka, & Skomorucha, (2021). Bilberry and walnut leaves were reported to significantly (p < 0.05) decreased egg weight in 32-wk-old Tetra SL laying hens (Untea et al., 2020). Although these authors assumed that anthocyanins or other compounds might be responsible for decreasing egg weight, recent studies contradict them. Anthocyanins rich diets, supplemented with chokeberry, black currant, and raspberry (Sosnówka-Czajka and Skomorucha, 2021) or 200 and 400 mg/kg anthocyanin-rich roselle (Li et al., 2023) had no detrimental effect on egg characteristics during long term feeding (20 wk) of Hy-Line commercial hybrid laying hens at peak production (42 wk old) or late laying phase (88 wk old) Chishui black-bone hen. Further, the significant changes in albumen, yolk, and yolk/albumen ratio, are directly correlated with the modifications of egg and yolk weight. These results revealed that while rosehip leaves supplementation did not result in significant changes in egg quality parameters, in time, the age of laying hens had notable effects on various aspects of egg quality, being correlated with longer feeding duration.
Samiullah et al. (2017), reported that beside age, raising systems (free range, cage, or barn), type of hybrid used, environmental temperature and feed could affect these parameters. In the study of Rizzi and Chiericato, (2005), it was showed that regardless of the type of hybrid, the egg weight is increasing at a rate dependent with the genetic potential of the hybrid used. Nevertheless, the findings from this study suggest that longer-term supplementation of rosehip leaves and maturation periods might enhance certain egg quality traits in laying hens later, during peak production or late laying phase.
The investigation into the effects of rosehip leaves supplementation on egg yolk and albumen color, as determined by CIE chromameter analysis, shows the potential of natural feed additives to enhance egg color parameters in laying hens. The current findings reveal significant improvements in egg yolk color parameters, including L*, a*, b*, ΔE*, Δa*, Δb*, and ΔL*, with the inclusion of rosehip leaves in the diet. The RL0.5 and RL1 showed a consistent trend of enhancement in egg yolk coloration. Higher levels of rosehip leaves were associated with lighter (higher L*) and more yellowish (higher b*) yolk color. Notably, 1% of rosehip leaves supplementation resulted in most substantial changes in egg yolk color, with higher ΔE* values indicating more substantial changes in color from the control group, indicating a dose-dependent response. With the hens age, there was a general trend of improvement in egg yolk color, as indicated by increasing values of L*, a*, b*, and ΔE* over the laying period. These changes in time of egg yolk coloration shows the dynamic nature of pigmentation in egg yolks, with the accumulation of carotenoids over time contributing to more vibrant and desirable coloration. Rosehip leaf supplementation also exerted a significant effect on egg albumen color parameters. The experimental groups supplemented with dietary rosehip leaves were associated with higher values of L* and b*, indicating lighter and more yellowish albumen coloration. Hens age also played a significant role in modulating egg albumen color, with notable variations observed over the laying period (28, 30, and 30 wk of hens). Notably, as in the case of yolks, the highest levels of rosehip leaves (RL1%) supplementation resulted in the most significant changes in albumen color, as indicated by higher ΔE* values, suggesting more substantial changes in color compared to the RL0 group.
Titcomb et al. (2019), reported that green leaves (carrot and marigold leaves) are concentrated sources of xanthophylls (lutein and zeaxanthin) leading to enhanced yolk color, and enrichment in these bioactive compounds. Similarly, plants like basil, calendula, and dandelion flowers, used in first stage of Tetra SL (22-wk-old) laying hens positively impacted egg yolk color (Kljak et al., 2021). Pastures of grass, alfalfa and stinging nettle are also plant sources with high potential of influencing the egg yolk (Hammershøj & Johansen, 2016). The effect of rosehip leaves supplementation in laying hen diets on egg yolk color was not reported previously. Higher egg yolk color attributed to the presence of carotenoids pigment in rosehip leaves, has a major impact in consumers seeking for more yellow-orange yolk pigments. Further research could explore different supplementation levels and duration to maximize the beneficial effects of rosehip leaves on egg yolk and albumen color.
The chemical composition of eggs albumen, yolk, and shell provides insights into the impact of rosehip leaves supplementation and hens age on these components. Rosehip leaf supplementation did not significantly influence the chemical composition of eggs yolk, or shell, irrespective of the rosehip leaves levels (0%, 0.5%, and 1%), in dry matter (DM), crude protein (CP), ether extract (EE), or ash content. Only the CP in egg albumens was significantly higher in RL1 compared with RL0.5 and RL0 groups. With the hens age, a significant effect was noted for crude protein in egg albumen and crude fat in egg yolks of RL1. However, these changes were relatively minor and may not have practical significance in terms of egg quality or nutritional value. Comparing our findings with literature data on the effects of dietary plants as natural feed additives on egg composition, our results align with studies indicating limited impact of natural feed additives on the chemical composition of eggs. Mentha arvensis and Geranium thunbergia, had no effect on proximate composition of eggs as recently reported (Dilawar et al., 2021). Other plant feed additives such as nettle (Nobakht et al., 2011), alfalfa and nettle Urtica cannabina (Zhang et al., 2020), had no effect on chemical composition of the eggs, regardless of the age of the hens or hybrids. Some studies have reported minor alterations in egg composition like albumen protein or yolk fat with major dietary interventions. Albumen protein can be altered by feeding laying hens with seeds of legume plants as soybean replacement (Kuzniacka et al., 2020; Obianwuna et al., 2022). The crude fat content of the yolk can be altered by feeding laying hens oleaginous seeds or meals, like flaxseed, camelina or rapeseed (Orczewska-Dudek et al., 2020; Vlaicu et al., 2021; Palomar et al., 2023). However, further research is warranted to explore potential interactions between rosehip leaves, long-term feeding and other dietary components that may influence egg chemical composition.
The effect of rosehip leaves was not significant among individual fatty acids, determined in the egg yolks after 6 wk of feeding experimental diets. However, significant alterations were noted among the quality classes of the fatty acids profile. The total SFA were significantly higher (p < 0.05) in the RL1 yolks, compared with the RL0 and RL0.5. Also, the RL1 yolks, contained significantly lower (p < 0.05) of total MUFA compared with the other yolk samples, without any effect on total PUFA between the groups. This led to a significant increase in the PUFA/MUFA ratio of RL1 group compared with the RL0 and RL0.5. In contrast, other authors (Zhao et al., 2013) reported that Lohmann Brown laying hens aged 49 wk fed a diet containing 0.5% fermented Ginkgo-leaves, resulted in lower SFA and higher MUFA. The use of 1% thyme or rosemary extracts given to the Bowans White 48-wk-old layers had no effect on sums of SFA, MUFA or PUFA (Cimrin et al., 2019). A significant increase in total n-3 fatty acids (1.40 versus 1.18) and significant decrease in total n-6 fatty acids (29.85 versus 30.65) was observed only for RL1 yolks compared to RL0 yolk samples. Although rosehip leaves cannot be considered sources of fat, it was reported that plant feed additives, through their antioxidant profile have a protective effect on PUFA from oxidative breakdown (Vlaicu et al., 2021; Tadesse et al., 2023). Another reason for fatty acids alteration in eggs is the hens age and hybrid used. A study conducted for 26 wk, starting at initiation of laying period (wk 16) until mid of peak production (wk 42), showed that moringa oleifera leaves (0.5, 1, and 1.5%) significantly improved the PUFA profile, especially the total of n-3 compared to control diet (Sharmin et al., 2021). This effect was recently confirmed by other authors (Tadesse et al., 2023, Mierlita et al., 2024). Moreover, these results show that the action of the enzyme in the formation and depletion of fatty acids starts from the first stage of egg deposition. Further, the significant modification of total n-3 and n-6 fatty acids led to significantly decreased n-6/n-3 ratio in both RL0.5 and RL1 yolk samples compared with those from RL0 group. This alteration in the n-6/n-3 ratio in poultry products is a wanted effect as this parameter is considered undesirable due to its potential to increase cholesterolemia (Vlaicu et al., 2022b). All in all, further research is required to elucidate the effect of higher doses of rosehip leaves during longer periods of feeding to explore its potential beneficial effects on laying hens production performances and eggs quality.
CONCLUSIONS
It can be concluded that dietary rosehip leaves as feed additives used in the first stage of laying hens egg deposition, could significantly improve the production performance. The addition of 1% of rosehip leaves was effective in altering the egg color parameters, as well as improving the sum of total n-3 PUFA. These results could open a new door in exploring the beneficial co-products derived from unexplored rosehip parts.
