Abstract This experiment investigated the effect of 2:1 ratio of calcium (Ca) to non-phytate phosphorus (NPP) over a range of their concentrations on performance of broilers in phase 1 (1–24 days), phase 2 (25–38 days) and the whole period. A total of 900 male broilers were allocated into 60 pens. In phase 1, dietary treatments were high (H, 9.6 g/kg Ca and 4.8 g/kg NPP), moderate (M, 7.6 g/kg Ca and 3.8 g/kg NPP), low (L, 5.6 g/kg Ca and 2.8 g/kg NPP) and very low (VL, 3.6 g/kg Ca and 1.8 g/kg) level of Ca and NPP. H and M diets showed higher average daily feed intake (ADFI) and serum Ca than those of L and VL diets. There was a linear decrease in tibia Ca and serum P and a linear increase in relative expression of SLC20A1 and CALB1 and retention of Ca and P when concentration of Ca and NPP was reduced. H diet resulted in the highest tarsometatarsus strength and feed conversion ratio (FCR). M and L diets showed higher average daily gain (ADG) than those of H and VL diets. VL diet demonstrated the lowest tibia ash. On day 25, treatments H, M, L and VL received, respectively, 4, 3, 2 and 1 types of finisher diets (H, M, L and VL) during phase 2, resulting in a total of 10 treatments; HH, HM, HL, HVL, MM, ML, MVL, LL, LVL and VLVL. HH vs. HM vs. HL vs. HVL showed a linear decrease of ADFI, ADG, serum P, tibia ash, tarsometatarsus strength and a linear increase of FCR. HH vs. MM vs. LL vs. VLVL demonstrated a linear increase of relative expression of CALB1 and SLC20A1 and a linear decrease of serum P, and in terms of growth performance, MM showed the best results generally. MM vs. ML vs. MVL showed a linear decrease of ADFI and ADG and a linear increase of FCR. HM vs. ML vs. LVL demonstrated a linear decrease of ADG, serum Ca and P and relative expression of CALB1 and a linear increase of FCR (during phase 2). In conclusion, reducing Ca and NPP level over finisher phase, similarly for all combinations of treatments, resulted in poorer performance either in finisher phase or the whole period. Generally, 7.6 g/kg Ca and 3.8 g/kg NPP over the whole period maximized broiler’s performance without negative effects on bone ash and strength.

中文翻译：

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在起始-生长阶段和育肥阶段，在一定浓度范围内，钙与非植酸磷比例恒定为 2:1 对肉鸡生产性能的影响

摘要 本实验研究了钙 (Ca) 与非植酸磷 (NPP) 的 2:1 比例在其浓度范围内对第 1 阶段（1-24 天）、第 2 阶段（25-38天）和整个时期。总共 900 只雄性肉鸡被分配到 60 个围栏。在第 1 阶段，日粮处理高（H，9.6 g/kg Ca 和 4.8 g/kg NPP），中等（M，7.6 g/kg Ca 和 3.8 g/kg NPP），低（L，5.6 g/kg Ca和 2.8 g/kg NPP）和非常低（VL，3.6 g/kg Ca 和 1.8 g/kg）Ca 和 NPP 的水平。H 和 M 日粮显示出比 L 和 VL 日粮更高的平均日采食量 (ADFI) 和血清钙。当 Ca 和 NPP 浓度降低时，胫骨 Ca 和血清 P 线性降低，SLC20A1 和 CALB1 的相对表达以及 Ca 和 P 的保留线性增加。H 饮食导致跗跖肌强度和饲料转化率（FCR）最高。M 和 L 饮食显示出比 H 和 VL 饮食更高的平均日增重 (ADG)。VL 饮食表现出最低的胫骨灰分。在第25天，处理H、M、L和VL在第2阶段分别接受4、3、2和1种肥育日粮（H、M、L和VL），总共10个处理；HH、HM、HL、HVL、MM、ML、MVL、LL、LVL 和 VLVL。HH vs. HM vs. HL vs. HVL 显示 ADFI、ADG、血清 P、胫骨灰分、跗跖骨强度线性下降和 FCR 线性增加。HH vs. MM vs. LL vs. VLVL显示CALB1和SLC20A1的相对表达线性增加，血清P线性下降，在生长性能方面，MM普遍表现出最好的结果。MM vs. ML vs. MVL 显示 ADFI 和 ADG 线性减少，FCR 线性增加。HM 与 ML 与 LVL 显示 ADG、血清 Ca 和 P 以及 CALB1 的相对表达和 FCR 的线性增加（在第 2 阶段）。总之，在精整阶段降低 Ca 和 NPP 水平，类似地对于所有处理组合，导致精整阶段或整个时期的性能较差。一般来说，在整个时期内，7.6 g/kg Ca 和 3.8 g/kg NPP 可以最大限度地提高肉鸡的生产性能，而不会对骨灰分和强度产生负面影响。导致在终结者阶段或整个阶段的表现较差。一般来说，在整个时期内添加 7.6 g/kg Ca 和 3.8 g/kg NPP 可以最大限度地提高肉鸡的生产性能，而不会对骨灰分和强度产生负面影响。导致在终结者阶段或整个阶段的表现较差。一般来说，在整个时期内，7.6 g/kg Ca 和 3.8 g/kg NPP 可以最大限度地提高肉鸡的生产性能，而不会对骨灰分和强度产生负面影响。