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.

摘要

随着对无抗生素生产的呼吁和对家禽天然饲料添加剂的关注。本研究评估了新鲜柠檬 (FM) 补充剂对老年蛋鸡（79-96 周）的影响及其与柠檬酸 (CA) 和黄霉素 (FLA) 的比较。雌性精粉鸡 ( n  = 540) 随机分配到 5 个日粮处理：0（对照）、20 g/kg (2%) 和 40 g/kg (4%) FM、0.7 g/kg CA 和 0.005 g/kg佛罗里达州。每天记录生产性能，每两周测量一次鸡蛋质量特性。从 84 至 96 周龄，每 4 周检测一次血清生化指标和抗体滴度。与对照日粮相比，FM、CA 和 FLA 提高了产蛋率（p < .05) 和平均日采食量 (ADFI)，并降低料蛋比 (FER)，表明对生产性能产生积极影响。与对照组相比，FM 组的蛋白高度和 HU 增加了 2% 和 4%，而 CA 和 FLA 组的蛋白高度降低。 与其他组相比，FM 改善了血清抗氧化酶活性 ( p < .05) 并降低了血清 HDL、LDL、TG 和 T-CH，表明对抗氧化状态和脂质代谢有有利影响。FM组的H5N1、H9N2和NDV抗体滴度在大多数实验期间均高于其他组（p < .05）。综上所述，FM补充提高了蛋鸡产蛋后期的生产性能和抗氧化能力，在改善蛋白质量、免疫状态和脂质代谢方面优于CA和FLA。

• 强调

• 在蛋鸡日粮中添加 FM 对生产性能、蛋清质量和脂质代谢有积极影响，并可提高抗氧化能力和免疫水平。

• 在蛋鸡后期添加FM比添加CA和FLA对蛋鸡的蛋白质量、免疫状态和脂质代谢有更好的影响。