Effect of pomegranate peel powder extract (ethanolic) on performance, egg quality, thyroid hormones, antioxidant parameters, interferon γ, lipid and protein profiles of aged laying hens

Pomegranate peel extract is rich in total phenolics with high antioxidant activity. Furthermore, prolonging the laying period of hens is a growing trend that offers both financial and environmental benefits. Therefore, the current study aimed to investigate the potential effects of Pomegranate peel powder extract (PPPE) on aged laying chickens. One hundred twelve ISA White chickens, 80 weeks old, were randomly distributed into 4 groups, with seven replicates of 4 birds each. The first group received a basal diet (control group), which contains 170 mg of crude protein/kg diet with 2800 Kcal ME/kg of diet, while the second, third, and fourth groups received a basal diet supplemented with PPPE at levels of 100, 200, and 300 ppm, respectively. For daily egg mass (EM) per hen, egg production (EP%), feed conversion ratio (FCR), eggshell strength (kg/cm2), Haugh unit, total protein (TP), and globulins (G) were significantly (p < 0.001) improved by adding 100 ppm of PPPE in laying hens’ diets compared to other treatments. Furthermore, all hens receiving the experimental treatments had the best yolk color, yolk weight, yolk/albumin ratio, shell weight of egg, plasma total cholesterol (Cholest), low-density lipoprotein, T3, and T3/T4 ratio. The shell thickness was recorded as the highest value in birds receiving 200 ppm. Furthermore, laying hens fed a diet supplemented with PPPE100 recorded the highest total antioxidant capacity (TAOC) and phosphorus levels of plasma and the lowest interferon γ (INF-γ) and plasma calcium levels. In conclusion, supplementing PPPE at 100 ppm to the basal diet improved aged laying hens’ performance, quality and strength of eggs, TAOC, (INF-γ), Cholest, LDL, and liver function. In addition, more studies are required to investigate PPPE in laying chickens, especially in the last production phase.