本试验旨在研究包膜酸化剂和小肽螯合铁及其互作对38~44周龄蛋鸡夏季产蛋性能、蛋品质及血清生化指标的影响。采取2×4完全随机试验设计，在基础饲粮设2个包膜酸化剂添加水平（0和300 mg/kg）和4个小肽螯合铁添加水平（0、0.04%、0.08%和0.12%）。试验选用38周龄、健康的罗曼粉壳蛋鸡576只，随机分成8组，每组6个重复，每个重复12只。A、B、C和D组饲粮分别在基础饲粮中添加0 mg/kg包膜酸化剂和0（对照组）、0.04%、0.08%或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包膜酸化剂和0、0.04%、0.08%或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）包膜酸化剂以及包膜酸化剂和小肽螯合铁互作对哈氏单位有显著影响（P<0.05）。B、H组总产蛋数较对照组分别提高了4.57%、4.45%（P>0.05），F组蛋壳厚度显著大于对照组（P<0.05），B、H组料蛋比显著小于G组（P<0.05），E、F和G组哈氏单位显著高于D组（P<0.05）。2）包膜酸化剂对血清中各生化指标均无显著影响（P>0.05），小肽螯合铁对血清中钙、磷、铁含量有显著影响（P<0.05），包膜酸化剂和小肽螯合铁互作对血清中总胆固醇、钙、磷含量有显著影响（P<0.05）。D组血清碱性磷酸酶活性显著低于对照组（P<0.05），H组血清中总胆固醇含量显著低于B、C组（P<0.05），并较对照组降低了15.48%（P>0.05），B、F组血清中钙含量显著高于E组（P<0.05），C组血清中磷含量显著高于E组（P<0.05），C组血清中铁含量显著高于对照组和E、H组（P<0.05）。综合考虑，在饲粮中单独添加0.04%小肽螯合铁或与300 mg/kg包膜酸化剂复合使用，均有利于提高38~44周龄蛋鸡夏季的产蛋性能，并可改善蛋品质和血清生化指标。

This experiment was conducted to evaluate the effects of coated acidifier and small peptide chelated iron and their interaction on laying performance, egg quality and serum biochemical parameters of 38- to 44-week-old laying hens in summer. A 2×4 factorial completely randomized design was adopted with 2 supplemental levels (0 and 300 mg/kg)of coated acidifier and 4 supplemental levels (0, 0.04%, 0.08% and 0.12%)of small peptide chelated iron in the basal diet. A total of 576 healthy Lohmann pink-shell laying hens (38-week-old) were randomly allotted to 8 groups with 6 replicates of 12 hens per replicate. 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% or 0.12% small peptide chelated iron (the content of iron 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% or 0.12% small peptide chelated iron (the content of iron was 0, 60, 120 and 180 mg/kg, respectively). The adjustment period lasted for 1 week, and the experimental period lasted for 6 weeks. The results showed as follows:1) coated acidifier and the interaction of coated acidifier and small peptide chelated iron had a significant effect on Haugh unit (P<0.05). Total egg number in groups B and H was increased by 4.57% and 4.45%, respectively, compared with control group (P>0.05). Egg shell thickness in group F was significantly higher than that in control group (P<0.05). Feed to egg ratio in groups B and H was significantly higher than that in group G (P<0.05). Haugh unit in groups E, F and G was significantly higher than that in group D (P<0.05). 2) Coated acidifier had no significant effects on serum biochemical parameters (P>0.05). Small peptide chelated iron had significant effects on serum calcium, phosphorus and iron contents (P<0.05). The combination of coated acidifier and small peptide chelated iron had significant effects on serum total cholesterol, calcium and phosphorus contents (P<0.05). Serum alkaline phosphatase activity in group D was significantly lower than that in control group (P<0.05). Serum total cholesterol content in group H was significantly lower than that in groups B and C (P<0.05), and was decreased by 15.48% compared with control group (P>0.05). Serum calcium content in groups B and F was significantly higher than that in group E (P<0.05). Serum phosphorus content in group C was significantly higher than that in group E (P<0.05). Serum iron content in group C was significantly higher than that in control group and groups E and H (P<0.05). In conclusion, adding 0.04% small peptide chelated iron alone or combined with 300 mg/kg coated acidifier are beneficial to improve the laying performance, egg quality and serum biochemical parameters of 38- to 44-week-old laying hens in summer.