Feed analysis
The ingredient composition and nutrient content of the feeds used in the experiment are given in Table 1.
Analysis of dandelion root
The active principles present in dandelion root is presented in Table 2 and depicts the phenolic compounds present in dandelion root.
Productive performance of birds
The addition of 5 g/kg dandelion to the basal diet significantly increased egg production compared to other groups (Table 3). The reason for this situation is thought to be shaped depending on the dose of dandelion root added to the ration. Canto
Saenz et al., (2021) also observed that the inclusion of the dandelion (1,2,3,4% levels) and CPB (0.20% of sodium butyrate) in the diet of laying hens improved egg production significantly. Herbal extracts have a stimulating effect on animal digestive systems and these effects could be due to the increased production of digestive enzymes and the improved utilization of digestive products through enhanced liver functions (
Jamroz, 2003).
Egg production decreased significantly in the group fed with high-energy feed. This result is confirmed by previous studies showing lower egg production in a HE diet
(Ürüşan, 2021; Ürüşan, 2023). High quantities of fat or energy intake cause metabolic burden with increased fat accumulation in the liver, which leads to a decrease in laying rate
(Neijat et al., 2014).
Although not statistically significant, the addition of dandelion to the diet decreased feed intake. Smilar findings were reported by
Quilcate et al., (2018) they observed that dandelion supplementation (4%) in laying hen diets decreased feed intake. It is possible that a high amount of sesquiterpenic lactones (bitter principle) in dandelion that are responsible for the flavor and bitter taste, may have reduced feed consumption in birds.
Schleicher et al., (1998) observed that herbal plants like chamomile and dandelion had negative impacts on FCR and live body weights (LBW) at 52 days of age in broilers.
Limin et al., (2016), reported that dietary astragalus polysaccharides and dandelion extracts at the level of 0.1% decreased feed consumption of laying hens. Conversely,
Qureshi et al., (2015) revealed that a combination of enzyme-treated fenugreek seeds and dandelion leaves supplementation improved FI in broilers. It is believed that this is due to the difference in the type, dose and duration of administration of dandelion added to the diet as a justification for this condition.
In this study, it was determined that the addition of dandelion to the diet did not affect egg weight. But the highest value was for the HE+dandelion 5 g/kg group (62.85 gr). However,
Limin et al., (2016) reported that egg weight in groups fed astragalus polysaccharides and dandelion extracts were higher than those in control group. However,
Quilcate et al., (2018) showed that dietary inclusion of dandelion, reduced the weight of the egg. This could be because dandelion was supplemented in the diet at high level.
The addition of dandelion to the diet had no impact on FCR. Consistent with current findings,
Quilcate et al., (2018) revealed that the addition of dandelion in the laying hen diet did not affect FCR. Similarly,
Maljik (2017) showed that dandelion addition did not affect performance parameters.
Egg quality
The experimental results indicated that shell weight was significantly increased by dandelion in high energy diet (p<0.05) (Table 4). Similarly,
Maljik (2017) showed that dietary dandelion in laying hens improved the shell weight of eggs. Dandelion is a good source of calcium and vitamin K, both of which could have contributed to improvement in shell weight. The addition of 5 and 15 g/kg dandelion to the high energy diet increased significantly egg weight compared to other groups.
For consumers, one of the important purchasing criteria of eggs yolk color (
Esfahani-Mashhour 2009). Supplementation of Dandelion in layers has been less studied as source of pigment for egg yolk coloration
(Ürüşan, 2021; Quilcate et al., 2018). This study revealed that supplemental dandelion increased (p<0.05) the yolk color score. This was largely due to carotenoids present in dandelion. Consistent with current findings,
Maljik (2017) and
Quilcate (2018) also observed that the yolk color index was promoted as the result of dietary addition of dandelion. Dandelion also has high antioxidant activity (
Hu and Kitts 2003;
Sahingil 2019), suggesting that its supplementation could protect fatty acids in egg yolk and thus affect not only color and carotenoid content but also oxidative stability and sensory properties. Thus, it could be a suitable alternative to improve egg quality and provide beneficial bioactive compounds in the human diet.
Shape index values (%) were significantly affected by all the treatments with the values ranging between 68.50 and 75.10%. An important criterion in determining egg quality is the egg shape index. An egg is always oval in shape (72-76). Round eggs and unusually long eggs do not fit well in egg cartons. Hence, they are much more likely to break during the shipment than the eggs of normal shape
(Sarıca and Ersayın, 2009). The group fed with high energy diet showed the lowest shell thickness. It has been suggested that especially calcium-binding protein synthesis is impaired due to fatty liver in high-energy diets and as a result, Ca++ absorption from the intestines decreases (
Sevinç and Aslan 1998). In the current study, it is thought that there may be a decrease in egg shell thickness due to the decrease in calcium absorption in the HE+group.
Blood serum constituents
Dandelion has many bioactive components, phenolic compounds, glycosides, alkaloids, tannins and flavonoids. It plays a role in reducing cholesterol levels in the blood by intensification of bile secretion
(Choi et al., 2010). Data showed that serum triglyceride and VLDL concentrations were lower in the control and HE + 5 g/kg dandelion groups than the other groups (p<0.01).
Qureshi et al., (2015) were found that serum cholesterol was decreased significantly in the groups fed a combination of fenugreek seeds and dandelion leaves with or without enzyme as compared to the control. Similarly,
Choi et al., (2010) showed that treatment with dandelion root and leaf decreased plasma triglycerides and LDL cholesterol in cholesterol-fed rabbits. Concerning the hypolipidemic effect, many studies have indicated that dandelion reduces the concentrations of cholesterol and triglyceride in the blood
(Qureshi et al., 2015; Jassim et al., 2012; Davaatseren 2013b). The addition of dandelion in the diet of laying hens had no significant differences in ALP, AST, ALT, glucose, total cholesterol, LDL, HDL and estrogen concentration (Table 5).
MDA has been widely used as an indicator of lipid peroxidation. The lowest MDA concentrations were observed in controls, HE 5 g/kg and 10 g/kg dandelion groups. CAT, SOD and GSH-Px are important anti-oxidant enzymes playing a role in reducing toxic effects. They can work together to catalyze free superoxide anion radicals into nontoxic compounds
(Xiaohong et al., 2016). The GSH value was significantly increased in the control, HE and 10 g/kg dandelion groups (p<0.01) (Table 6). Consistent with present findings,
Choi et al., (2010) observed that GSH activities were significantly improved in both dandelion root and leaf groups, compared to the control group in cholesterol-fed rabbits. Using 10 g/kg dandelion as feed additive in high energy diet had the highest CAT and GPx enzyme value during the experimental period, compared with other treatment groups. Studies have shown that dandelion has significantly increased hepatic antioxidant enzymes (GPx, GST and GSH)
(Choi et al., 2010; You et al., 2010). The results show that dandelion reduced lipidic superoxide damage, improved the antioxidative status and inhibited free radical formation in laying hens.
Weight and fat ratio of liver
The liver weights (dry and wet) of the laying hens were not influenced significantly (p>0.05) by any of the treatments. The liver fat content decreased in HE+5g/kg, HE+15 g/kg dandelion and control diets compared with other groups (p
<0.05) (Table 7). Literature review has revealed that dandelion has protective activity in the liver. It has been reported that the lipid-lowering effect of dandelion is due to the relationship of luteolin with hydroxy-methyl-glutaryl-enzyme A reductase, liver sterol regulatory element-binding proteins and acetyl-CoA C-acetyltransferase (
Gebhardt 2002). Although there are several studies with dandelion, none of the research has been conducted to appreciate the influence of the hepatoprotective effect of dandelion in laying hens. A search of the literature found only the report by
Davaatseren et al., (2013a) which recommended that dandelion leaf extract could inhibit hepatic lipid accumulation in high-fat diet-fed mice. In addition,
Cho et al., (2002) dandelion water extract addition could be used to improve lipid metabolism in rats. At present, hepatoprotection is used in the integrated therapy of liver diseases. A reduction in relative liver fat in laying hens fed dandelion at 5 g/kg with high energy is promising.
