Dietary fresh lemon improves the albumen quality, immune status and lipid metabolism of Jingfen laying hens during the late laying period

Abstract

With the appeals for antibiotic-free production and the attention to natural feed additives in poultry. The effects of fresh lemon (FM) supplementation on older laying hens (79–96 weeks) and its comparison with citric acid (CA) and flavomycin (FLA) were evaluated in the present study. Female Jingfen chickens (n = 540) were randomly distributed into 5 dietary treatments: 0 (control), 20 g/kg (2%) and 40 g/kg (4%) FM, 0.7 g/kg CA and 0.005 g/kg FLA. Production performances were recorded daily and egg quality traits were measured biweekly. Serum biochemical indices and antibody titres were detected every 4 weeks from 84 to 96 weeks of age. Compared with the control diet, FM, CA and FLA increased the laying rate (p < .05) and average daily feed intake (ADFI), and reduced the feed to egg ratio (FER), indicating positive effects on production performance. Albumen height and HU were increased by 2% and 4% FM groups compared to the control, while albumen height was decreased in CA and FLA groups. FM improved serum antioxidant enzyme activities (p < .05) and reduced serum HDL, LDL, TG and T-CH compared to other groups, indicating favourable effects on antioxidative status and lipid metabolism. Antibody titres against H5N1, H9N2 and NDV were higher in FM groups than that in other groups during most experimental periods (p < .05). In conclusion, FM supplementation enhanced the production performance and antioxidant capacity of laying hens during the late laying period and was superior to the CA and FLA in improving albumen quality, immune status and lipid metabolism. HIGHLIGHTS FM supplementation in layers’ diets had positive effects on production performance, egg albumen quality and lipid metabolism, and could enhance antioxidant capacity and immune levels. Adding FM had better effects on the albumen quality, immune status and lipid metabolism of laying hens than adding CA and FLA during the late laying period.