Effect of adding green tea and its aqueous extract as natural antioxidants to laying hen diet on productive, reproductive performance and egg quality during storage and its content of cholesterol.

The aim of this study was to investigate the effect of adding green tea and its aqueous extract as natural antioxidants to local laying hen diets on productive, reproductive performance and egg quality during storage and its content of cholesterol. In this study, a total number of 168 Inshas hens and 21 Inshas cocks, 34 weeks of age were randomly distributed into 7 groups and fed on the experimental diets. The experimental diets were as follows: three levels of green tea leaves (1, 3 and 5% of the diet) in comparison to their water extract at 0.5, 1.5 and 2.5 L / 100 kg diet, respectively), in comparison with the basal diet. The results of this study showed that adding between 1-5(%) green tea leaves (GTL) or between 0.5-2.5 (L/100 kg diet) green tea aqueous extract (GTE) to Inshas hen diets improved their productive performance, without significant differences between all tested levels of additives. The improvements in egg production, egg mass and feed conversion values, due to 1% GTL, compared to the control were 5.59%, 6.79% and 7.84%, respectively. While the corresponding level (0.5 L/100 kg diet) of aqueous extract (GTE) resulted in 6.78%, 7.46% and 8.65% improvement, respectively. None of the treatments had adverse effect on the change of hen body weight. More than 1% green tea leaves (3 and 5%) and more than 0.5 L/100 kg diet green tea extract (1.5 and 2.5) were required to improve significantly (P≤0.05) both of external and internal egg quality parameters. The improvement in shell thickness values (mm), due to 3% GTL or the corresponding level (1.5 L/100 kg diet) of water extract (GTE), compared to the control was 6.88%. Yolk color score was not influenced significantly by Zeinab M. A. Abdo, et al. 1122 any of the treatments. However, there was a gradual increase in yolk color score with increasing levels of green tea leaves (GTL). Addition of 3 and 5% (GTL) or 1.5 and 2.5L/100 kg (GTE) to the diets could improve the reproductive performance of both Inshas hens and cocks. The improvement in hatchability of fertile eggs due to 3% GTL was 6.11%, while the corresponding level (1.5 L/100 kg diet) of water extract (GTE) resulted in 5.03% improvement. Water extract of green tea leaves (GTE) resulted in least TBARS of semen plasma, therefore more protection against peroxidative damage of sperm membranes. The improvements in sperm concentration (million/mm3) and dead sperm (%) due to 3% GTL, compared to the control were 11.16% and 20.87%, respectively. While the corresponding level (1.5 L/100 kg diet) of water extract (GTE) resulted in 23.51% and 12.07%, respectively. None of the treatments had significant effect on nutrient digestibility. Addition of 3 and 5% (GTL) or between 0.5 and 2.5 L/100 kg (GTE) to Inshas hen diets decreased significantly (P≤0.05) both total blood plasma cholesterol and total lipids and also 1.5 L/100 kg (GTE) was required to increase (P≤0.05) the beneficial blood plasma H.D. L.as compared with that of control. In addition there was no adverse effect on both liver and kidney functions. Green tea leaves (GTL) and (GTE) at all tested levels decreased significantly (P≤0.05) total cholesterol content in egg yolk, LDL, total lipids and triglycerides as compared with the control, while, 5% GTL and 1.5 L/100 kg GTE were required to increase significantly (P≤0.05) H.D. L. as compared with the control. Results also ascertained that adding green tea to hen diet kept egg content of pH, total bacterial count and coliform group and egg yolk malonaldehyde lower than that of the control up to 10 days storage at room temperature (20 to 23°C), and 60% RH, resulting in better egg quality compared with the control. Based on the results of the experiment, it is concluded that green tea powder inclusion in the diet for layers at 1.0-3.0% level or 0.50-1.5 L/100 kg water extract of green tea (GTE) can reduce the cholesterol content and TBA value of the egg yolk, implying its potential effect on egg quality parameters, especially during storage, in addition to improving the productive and reproductive performance of both hens and cocks.