Effect of different tea polyphenol products on egg production performance, egg quality and antioxidative status of laying hens

This study was conducted to determine the effects of different tea polyphenol (TP) products on egg production performance, egg quality and antioxidative status of laying hens. A total of 840 Lohmann pink shell laying hens (36-week-old) were randomly divided into 7 treatments for a 12-week feeding trial. The control group was fed a basal diet (no exogenous TP addition), and the experimental groups were fed the basal diet supplemented with approximately 1000 mg/kg of 6 types of tea polyphenols. The TP contents in 6 experimental diets were 1086.1, 944.2, 1111.4, 1037.9, 1074.1, and 1081.7 mg/kg and the caffeine concentrations were 4.4, 17.2, 30.9, 37.5, 73.8, and 128.5 mg/kg, respectively. In terms of performance, TP (except 1086.1 and 1074.1 mg/kg) reduced (P < 0.05) the average daily feed intake (ADFI) and the feed conversion ratio (FCR) during 1-4 week. Dietary TP supplementation at 944.2, 1074.1 and 1081.7 mg/kg increased the dirty egg rate (P < 0.01) and the addition of 1111.4, 1037.9 and 1081.7 mg/kg TP in basal diet decreased saleable egg rate (P < 0.05) during week 5 to week 8. The eggshell strength and eggshell weight of fresh egg at week 0, week 4 and week 8 were decreased by dietary TP sup-plementation (P < 0.05), with the TP groups (1074.1 and 1081.7 mg/kg) exhibiting the lowest eggshell strength and shell weight at week 0 and week 8. In addition, the lightness (L*) of eggshell color was decreased (P < 0.05), while the redness (a*) and yellowness (b*) was in-creased as TP intake increased (except 1086.1 and 1037.9 mg/kg) (P < 0.05). The albumen weight, yolk color, relative yolk weight and HU (Haugh unit) of fresh eggs at week 8 were higher or decreased (P < 0.05) as TP intake (except 1086.1 and 1074.1 mg/kg) increased. After 20-day storage, the eggshell strength, eggshell thickness and egg weight of eggs from hens fed the diets supplemented more than 1111.4 mg/kg TP (except 1074.1 mg/kg) were lower (P < 0.05) than those from control group. No effect of TP administration was found on serum glutathione per-oxidase (GSH-PX), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) concentra-tions. The results indicated that adding different tea polyphenol products in layers' diet led to a lower ADFI and improved FCR in a dosage-dependent manner during the first 4 weeks, but it impacted the hens' egg quality.