本试验旨在研究高、低钙饲粮交替饲喂对蛋鸡产蛋后期生产性能、蛋品质及血清指标的影响。试验选取68周龄的大午粉1号蛋种鸡64只，随机分为2组，每组32只，单笼饲养于个体智能鸡笼内，对照组08：00和14：00分别饲喂43.3、86.7 g中钙饲粮（钙含量为3.66%），试验组08：00饲喂43.3 g低钙饲粮（钙含量为2.00%），14：00饲喂86.7 g高钙饲粮（钙含量为4.49%）。试验期为5周，其中预试期1周，正试期为4周。结果显示：试验组各周的平均日采食量、平均蛋重、产蛋率、料蛋比与对照组无显著差异（P>0.05），但试验组各周的产蛋率在数值上高于对照组。试验组第2周的蛋壳厚度显著高于对照组（P<0.05），而试验组各周蛋白高度、哈氏单位与对照组无显著差异（P>0.05）。对照组中，18：00和22：00的血清钙含量显著高于10：00和14：00（P<0.05），高于06：00和次日02：00（P>0.05）；试验组中，22：00的血清钙含量极显著高于06：00、10：00、18：00和次日02：00（P<0.01），并显著高于14：00和18：00（P<0.05）；从06：00到22：00，试验组血清钙含量一直呈现增长的趋势，在22：00时，试验组血清钙、降钙素含量均显著高于对照组（P<0.05）。由此得出，高、低钙饲粮交替饲喂（将高钙饲粮在下午饲喂）可提高蛋鸡产蛋后期的产蛋率和对钙的吸收和沉积，并且可在一定程度上改善蛋壳质量。

The purpose of this experiment was to study the effects of alternation feeding of high and low calcium diets on performance, egg quality and serum indexes of laying hens at late period of laying. Sixty-weight 68-week-old Dawufen No.1 hen breeders were selected and randomly divided into 2 groups with 32 birds in each group, and single cage reared in individual intelligent cage. The laying hens in control group were fed 43.3 and 86.7 g middle calcium diet (calcium content was 3.66%) at 08:00 and 14:00, respectively. The laying hens in experimental group were fed 43.3 g low calcium diet (calcium content was 2.00%) at 08:00, and they were fed 86.7 g high calcium diet (calcium content was 4.49%) at 14:00. The test period lasted for 5 weeks including 1 week for pre-test period and 4 weeks for trial period. The results showed that the average daily feed intake, average egg weight, laying rate and feed/egg in the experimental group were not significantly different from those in the control group (P>0.05), but the numerical value of laying rate in the experimental group at each week of experiment was higher than that in the control group. The eggshell thickness at the 2nd week in the experimental group was significantly higher than that in the control group (P<0.05), but the albumen height and Haugh unit at each week had no significant differences between the experimental group and the control group (P>0.05). In the control group, serum calcium content at 18:00 and 22:00 was significantly higher than that at 10:00 and 14:00 (P<0.05), and higher than that at 06:00 and 02:00 (morrow) (P>0.05). In the experiment group, serum calcium content at 22:00 was significantly higher than that at 06:00, 10:00, 18:00 and 02:00 (morrow) (P<0.01), and significantly higher than that at 14:00 and 18:00 (P<0.05). From 06:00 to 22:00, serum calcium content in the experimental group showed an increasing trend. At 22:00, serum calcium and calcitonin contents in the experimental group were significantly higher than those in the control group (P<0.05). It is concluded that alternating feeding of high and low calcium diets (high calcium diet is fed in the afternoon) can increase laying rate and the absorption and deposition of calcium for laying hens at late stage of laying, and improve the eggshell quality to a certain extent.