日粮钙或磷缺乏对22~42日龄肉仔鸡生长性能及胫骨组织结构的影响

试验在前期研究日粮钙（Ca）或磷（P）缺乏对1~21日龄肉仔鸡生长性能及胫骨组织结构影响的基础上，进一步研究其对22~42日龄肉仔鸡上述指标的影响。采用2（钙水平：0.90%和0.30%）×2（非植酸磷（NPP）水平：0.35%和0.18%）两因子完全随机试验设计，选取504只1日龄爱拔益加肉公雏随机分为4组，饲养至22日龄时给与不同日粮处理：正常对照组（0.90%钙+0.35%非植酸磷）、磷缺乏组（0.90%钙+0.18%非植酸磷）、钙缺乏组（0.30%钙+0.35%非植酸磷）及钙和磷同时缺乏组（0.30%钙+0.18%非植酸磷），每个处理7个重复，测定22~42日龄肉仔鸡生长性能及28和42日龄胫骨组织结构。结果表明：与正常对照组相比，日粮钙或磷缺乏显著降低了肉仔鸡平均日采食量（ADFI）、平均日增重（ADG）和胫骨长度（P<0.05），而显著增加了肉仔鸡料重比（F/G）和胫骨生长板增生区长度（P<0.05）；磷缺乏组肉仔鸡的22~28日龄平均日采食量和平均日增重与28日龄胫骨长度显著低于钙缺乏组及钙和磷同时缺乏组（P<0.05）；磷缺乏组肉仔鸡的22~28日龄死亡率显著高于其他各组（P<0.05），该处理组肉仔鸡于28日龄时全部死亡；低钙水平显著增加了28日龄肉仔鸡胫骨生长板增生区长度（P<0.05），而低磷水平显著降低了28日龄肉仔鸡胫骨生长板增生区长度（P<0.05）。综上所述，22~42日龄肉仔鸡生长性能及胫骨组织结构对日粮磷缺乏最为敏感，其次为钙缺乏或钙和磷同时缺乏；低钙水平可增加肉仔鸡胫骨生长板增生区长度而低磷水平则相反。

Effect of Dietary Calcium or Phosphorus Deficiency on Growth Performance and Tibia Histological Structure of Broilers During 22 to 42 Days of Age

This experiment was conducted to investigate the effect of dietary calcium (Ca) or phosphorus (P) deficiency on growth performance and tibia histological structure of broilers from 22 to 42 days of age based on our previous study of broilers from 1 to 21 days of age.A total of 504 one-day-old Arbor Acres male broilers were randomly assigned to 1 of 4 treatments in a completely randomized design involving a 2 (Ca levels:0.90% and 0.30%)×2 (NPP levels:0.35% and 0.18%) factorial arrangement of treatments.The 4 treatment groups were the normal control group (0.90% Ca+0.35% NPP),the P-deficient group (0.90% Ca+0.18% NPP),the Ca-deficient group (0.30% Ca+0.35% NPP) and the Ca and P-deficient group (0.30% Ca+0.18% NPP).The growth performance of broilers from 22 to 42 days of age and the tibial histological structure at 28 and 42 days of age were measured.The results showed that dietary Ca or P deficiency decreased the average daily feed intake (ADFI),average daily gain (ADG) and tibia length of broilers (P<0.05),but increased the feed to gain ratio (F/G) and the length of tibia growth plate hyperplasia area (P<0.05).Furthermore,the broilers fed the P-deficient diet had the lowest ADFI and ADG of broilers from 22 to 28 days of age and tibia length at 28 days of age compared with those fed the Ca-deficient or Ca and P-deficient diets (P<0.05).Moreover,the broilers fed the P-deficient diet had the highest mortality during days 22 to 28 compared with other treatment groups (P<0.05),and all the broilers in this group died at 28 days of age.The low Ca level increased the length of tibia growth plate hyperplasia area of broilers at 28 days of age (P<0.05),but the low P level decreased it (P<0.05).In conclusion,the growth performance and tibia histological structure of broilers from 22 to 42 days of age were the most sensitive to dietary P deficiency,followed by dietary Ca deficiency or Ca and P deficiencies;And low Ca level increased while the low P level decreased the length of tibia growth plate hyperplasia area of broilers.