本试验旨在研究包膜酸化剂和小肽螯合铁及其交互作用对夏季产蛋高峰期蛋鸡生产性能、蛋黄中微量元素含量以及血清免疫和抗氧化指标的影响。试验采用2×4双因子完全随机试验设计，其中饲粮中包膜酸化剂设2个添加水平，小肽螯合铁设4个添加水平。选用576只38周龄健康罗曼粉壳蛋鸡，随机分成8个组，每组6个重复，每个重复12只鸡。A、B、C和D组饲粮分别在基础饲粮中添加0 mg/kg包膜酸化剂以及0（对照组）、0.04%、0.08%和0.12%小肽螯合铁（铁含量分别为0、60、120和180 mg/kg）；E、F、G和H组饲粮分别在基础饲粮中添加300 mg/kg包膜酸化剂以及0、0.04%、0.08%和0.12%的小肽螯合铁（铁含量分别为0、60、120和180 mg/kg）。预试期1周，正试期6周。结果表明：1）包膜酸化剂和小肽螯合铁及其交互作用对第3周和第6周蛋鸡的平均日采食量、产蛋率和料蛋比均无显著影响（P>0.05）。G组第3周和第6周的平均日采食量均显著高于对照组和C、D组（P<0.05）；B组第6周的产蛋率显著高于对照组和D、E组（P<0.05），且料蛋比显著低于D组（P<0.05）。包膜酸化剂对第3周末蛋鸡的蛋重、第6周末的蛋黄指数和哈氏单位有显著影响（P<0.05）；小肽螯合铁对第6周末的蛋黄指数有显著影响（P<0.05），小肽螯合铁和包膜酸化剂的交互作用对第6周末的蛋黄指数有极显著影响（P<0.01），对第6周末的哈氏单位有显著影响（P<0.05）。第3周末，G组的蛋重显著高于B组（P<0.05），G和H组的蛋黄指数显著高于C组（P<0.05）；第6周末，C、D和G组的蛋重显著高于对照组（P<0.05），F组的蛋黄指数显著高于C、D和E组（P<0.05），E、F和G组的哈氏单位显著高于D组（P<0.05）。2）小肽螯合铁及包膜酸化剂和小肽螯合铁的交互作用对第3周和第6周末蛋鸡蛋黄中铁元素含量有极显著影响（P<0.01）。B、C、D、F、G和H组第3周和第6周末蛋黄中铁元素含量极显著高于对照组和E组（P<0.01），且H组第3周末蛋黄中铁元素含量显著高于B和F组（P<0.05）；H组第3周末蛋黄中锌元素含量显著高于F组（P<0.05），B组第6周末蛋黄中锌元素含量显著高于D组（P<0.05）。3）包膜酸化剂对蛋鸡血清中总超氧化物歧化酶（T-SOD）活性有极显著影响（P<0.01），对血清丙二醛（MDA）含量有显著影响（P<0.05）；包膜酸化剂和小肽螯合铁的交互作用对血清T-SOD活性有极显著影响（P<0.01）。C组血清免疫球蛋白M（IgM）含量显著高于对照组（P<0.05），D、E、F、G和H组血清T-SOD活性极显著高于对照组（P<0.01）；B、F和G组血清MDA含量显著低于对照组和E组（P<0.05）。综合考虑，饲粮中单独添加0.04%和0.08%的小肽螯合铁或与300 mg/kg包膜酸化剂复合添加均有利于维持和延长蛋鸡夏季的产蛋高峰期，改善蛋品质，增加蛋中铁元素的富集，增强机体抗氧化能力。

This experiment was conducted to evaluate the effects of coated acidifier, small peptide chelate iron and their interaction on performance, the contents of trace elements in egg yolk and immune and antioxidant indices in serum of laying hens in egg laying peak in summer. Five hundred and seventy-six healthy Roman pink-shell laying hens at 38-week-old were randomly allotted to eight groups with six replicates per group and twelve hens per replicate according a 2×4 factorial completely randomized design with two supplemental levels of coated acidifier and four supplemental levels of small peptide chelate iron in the basal diets. The hens in groups A, B, C and D were fed the basal diet supplemented with 0 mg/kg coated acidifier and 0 (control group), 0.04%, 0.08% and 0.12% small peptide chelate iron (the content of Fe was 0, 60, 120 and 180 mg/kg, respectively), and those in groups E, F, G and H were fed the basal diet supplemented with 300 mg/kg coated acidifier and 0, 0.04%, 0.08% and 0.12% small peptide chelate iron (the content of Fe was 0, 60, 120 and 180 mg/kg, respectively). The pre-test lasted for one week, and the experiment lasted for six weeks. The results showed as follows:1) coated acidifier, small peptide chelate iron and their interaction had no significant effects on average daily feed intake (ADFI), laying rate and the ratio of feed to egg of laying hens at the 3rd and 6th weeks (P>0.05). ADFI in group G was significantly higher than that in the control group and groups C and D at the 3rd and 6th weeks (P<0.05), laying rate in group B was significantly higher than that in the control group and groups D and E at the 6th week (P<0.05), and the ratio of feed to egg in group B was significantly lower than that in group D at the 6th week (P<0.05). Coated acidifier had significant effects on egg weight at end of the 3rd week and egg yolk index and Haugh unit at end of the 6th week of laying hens (P<0.05), small peptide chelated iron had significant effect on egg yolk index at the end of the 6th week (P<0.05), and their interaction had significant effects on the egg yolk index (P<0.01) and Haugh unit (P<0.05) at end of the 6th week. At end of the 3rd week, egg weight in group G was significantly higher than that in group B (P<0.05), and egg yolk index in groups G and H was significantly higher than that in group C (P<0.05). At end of the 6th week, egg weight in groups C, D and G was significantly higher than that in the control group (P<0.05), egg yolk index in group F was significantly higher than that in groups C, D and E (P<0.05), and Haugh unit in groups E, F and G was significantly higher than that in group D (P<0.05). 2) Small peptide chelated iron and the interaction of coated acidifier and small peptide chelated iron had significant effect on the content of iron in egg yolk of laying hens at end of the 3rd and 6th weeks (P<0.01). The content of iron in egg yolk in groups B, C, D, F, G and H was significantly higher than that in the control group and group E at end of the 3rd and 6th weeks (P<0.01), the content of iron in egg yolk in group H was significantly higher than that in groups B and F (P<0.05) and the content of zinc in egg yolk in group H was significantly higher than that in group F (P<0.05) at end of the 3rd week, and the content of zinc in egg yolk in group B was significantly higher than that in group D at end of the 6th week (P<0.05). 3) Coated acidifier had significant effects on the activity of total superoxide dismutase (T-SOD) (P<0.01) and the content of malondialdehyde (MDA) (P<0.05) in serum of laying hens, and the interaction of coated acidifier and small peptide chelated iron had significant effects on the activity of T-SOD in serum (P<0.01). The content of immunoglobulin M (IgM) in serum in group C was significantly higher than that in the control group (P<0.05), the activity of T-SOD in serum in groups D, E, F, G and H was significantly higher than that in the control group (P<0.01), and the content of MDA in serum in groups B, F and G was significantly lower than that in the control group and group E (P<0.05). In conclusion, dietary 0.04% and 0.08% small peptide chelated iron alone or combined with 300 mg/kg coated acidifier is benefit to maintaining and extending the egg laying peak of laying hens in summer, improving egg quality, enrichment of iron in egg and enhancing antioxidant capacity.