为探讨碳酸氢钠(NaHCO₃)在蛋鸡生产中的安全剂量范围,本试验旨在研究饲粮添加不同水平NaHCO₃对蛋鸡生产性能和血常规指标、血清生化指标及血气指标的影响。选取900只21周龄海兰褐蛋鸡,随机分为对照组和1、5、25、50 g/kg NaHCO₃添加组,每组设6个重复,每个重复30只鸡,试验持续10周。结果表明:饲粮NaHCO₃的添加量不高于5 g/kg时不影响蛋鸡的生产性能(P>0.05),等于或高于25 g/kg时蛋鸡的产蛋率、采食量、产蛋重和平均蛋重显著或极显著降低(P<0.05或P<0.01),软破壳蛋率显著提高(P<0.05)。此外,血液pH、二氧化碳分压、碳酸氢根浓度、碱剩余、总二氧化碳浓度随NaHCO₃添加量的提高均有逐渐增加的趋势,除添加1 g/kg时的血液pH、二氧化碳分压与对照组无显著差异(P>0.05)外,其他均显著或极显著增加(P<0.05或P<0.01)。然而,饲粮添加NaHCO₃不影响血液红细胞数量、白细胞数量以及血清碱性磷酸酶活性、总蛋白浓度、白蛋白浓度、总胆红素浓度、谷草转氨酶活性和谷丙转氨酶活性(P>0.05)。但添加量为25～50 g/kg时,血液红细胞压积和血红蛋白浓度及血清尿素氮和肌酐浓度显著或极显著提高(P<0.05或P<0.01),血清葡萄糖浓度显著降低(P<0.05),同时添加量为50 g/kg时血小板数量显著低于其他各组(P<0.05)。由此可知,饲粮添加NaHCO₃超过25 g/kg,蛋鸡生产性能下降、血气指标改变,生理功能紊乱。而当NaHCO₃添加量低于5 g/kg时,蛋鸡可维持正常的生产性能和血液学稳态。这提示在蛋鸡生产中饲料添加剂NaHCO₃的安全剂量应低于5 g/kg。

This study was conducted to investigate the effects of dietary NaHCO₃ on performance, hematological indices, serum biochemical parameters and blood gas indices of laying hens, and to identify the safe dose range of sodium bicarbonate (NaHCO₃) in the diets of laying hens. Nine hundred 21-week-old Hy-Line brown laying hens were randomly assigned to 5 groups with 6 replicates per group and 30 birds per replicate. Laying hens were fed a basal diet with 0 (control group), 1, 5, 25 and 50 g/kg NaHCO₃ for 10 weeks, respectively. The results showed as follows: the performance of laying hens was not influenced by dietary NaHCO₃ supplemental level at ≤5 g/kg (P>0.05), but the laying rate, egg mass, feed intake, and average egg weight were significantly reduced (P<0.05 or P<0.01) and the ratio of broken and soft eggs was significantly increased (P<0.05) by dietary NaHCO₃ supplemental level at ≥25 g/kg NaHCO₃. In addition, the concentrations of HCO₃^- and total CO₂, partial pressure of CO₂, base excess, and pH in blood of laying hens were increased with increasing NaHCO₃ supplemental level, and significantly higher than those in the control group (P<0.05 or P<0.01) except that 1 g/kg NaHCO₃ did not affect pH and partial pressure of CO₂ (P>0.05). Moreover, the supplementation of NaHCO₃ did not affect the number of red blood cells and white blood cells, the activities of alkaline phosphatase, glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase and the concentrations of total protein, albumin, total bilirubin in serum of laying hens (P>0.05). However, blood hematocrit and the concentrations of hemoglobin in blood, creatinine and usea nitrogen in serum (P<0.05 or P<0.01) were markedly increased and the concentration of blood glucose in serum (P<0.05) was also significantly decreased by the supplementation of 25 to 50 g/kg NaHCO₃. Furthermore, the number of platelet in blood of laying hens in 50 g/kg NaHCO₃ group was notably lower than that in the other groups (P<0.05). It is concluded that excessive supplementation of NaHCO₃ (≥25 g/kg) can cause the decrease of performance, change of blood gas indices, and disorder of physiological functions of laying hens. However, the supplementation of NaHCO₃ at <5 g/kg can support the performance and assistant to maintain hematological levels in the physiological ranges of laying hens. Therefore, it is suggested that the safe dose of NaHCO₃ in diets of laying hens should be lower than 5 g/kg.