Department of Animal Science, Federal University of Lavras, Lavras, Brazil.
Department of Chemistry, Federal University of Lavras, Lavras, Brazil.
J Anim Physiol Anim Nutr (Berl). 2015 Feb;99(1):139-149. doi: 10.1111/jpn.12186. Epub 2014 Mar 31.
An experiment was conducted with broilers from 22 to 33 days of age to evaluate the efficiency of six microbial phytases supplemented in diets (1500 FTU/kg) that were formulated with three different calcium:available phosphorus (Ca:P(avail)) ratios (4.5:1.0, 6.0:1.0 and 7.5:1.0). A positive control diet without phytase was formulated with a Ca:P(avail) ratio of 7.5:3.4 to meet the nutritional requirements of the broilers. The P and ash contents of the tibia, magnesium in the plasma, performance, balance and retention of phytate phosphorus (P(phyt)), intake of total P and nitrogen (N), nitrogen-corrected apparent metabolizable energy and apparent digestibility of dry matter of the diets were not influenced (p > 0.05) by the type of phytase or the dietary Ca:P(avail) ratio. However, there was an interaction (p < 0.05) between the phytase type and the Ca:P(avail) ratio for the retention coefficients of total P, Ca and N. Phytase B resulted in the highest Ca deposition in the tibia (p < 0.01). Phytases D, E and F reduced the Ca concentrations in the tibia (p < 0.01) and plasma (p < 0.05). Phytase D increased the P level in the plasma and decreased the total P excretion (p < 0.01). Phytases E and F increased Ca excretion, while phytase A reduced it (p < 0.01). Regardless of the phytase type, increasing the dietary Ca:P(avail) ratio reduced (p < 0.05) the plasma P concentration and the excretion of total P and N and, conversely, increased (p < 0.05) the plasma concentration, intake and excretion of Ca. For the rearing period evaluated, it is possible to reduce the P(avail) of the diet to 1.0 g/kg when Ca is maintained at 7.5 g/kg, and the diet is supplemented with 1500 FTU of phytase A, C, D or E/kg. This diet allows the maintenance of performance and adequate bone mineralization, and it improves the Ca, total P and P(phyt) utilization in addition to reducing the excretion of N and P into the environment.
一项实验以 22 至 33 日龄的肉鸡为对象，评估了在三种不同钙：可利用磷（Ca：P（avail））比例（4.5：1.0、6.0：1.0 和 7.5：1.0）的日粮中添加六种微生物植酸酶的效率。不含植酸酶的阳性对照日粮按照 Ca：P（avail）比例为 7.5：3.4 进行配制，以满足肉鸡的营养需求。植酸酶的类型或日粮 Ca：P（avail）比例对胫骨的磷和灰分含量、血浆镁含量、性能、植酸磷（P（phyt））的平衡和保留、总磷和氮（N）的摄入量、氮校正表观代谢能和日粮干物质的表观消化率没有影响（p＞0.05）。然而，植酸酶类型和日粮 Ca：P（avail）比例之间存在互作（p＜0.05），影响总磷、钙和氮的保留系数。植酸酶 B 导致胫骨中钙沉积量最高（p＜0.01）。植酸酶 D、E 和 F 降低了胫骨（p＜0.01）和血浆（p＜0.05）中的钙浓度。植酸酶 D 增加了血浆中的磷水平，减少了总磷排泄量（p＜0.01）。植酸酶 E 和 F 增加了钙排泄量，而植酸酶 A 则减少了钙排泄量（p＜0.01）。无论植酸酶类型如何，增加日粮 Ca：P（avail）比例都会降低（p＜0.05）血浆磷浓度以及总磷和 N 的排泄量，相反，会增加（p＜0.05）血浆浓度、摄入量和钙排泄量。在评估的育肥期内，当钙保持在 7.5g/kg 时，可以将日粮的 P（avail）降低到 1.0g/kg，同时日粮中添加 1500FTU/kg 的植酸酶 A、C、D 或 E。这种日粮可维持生产性能和骨骼矿化程度，改善钙、总磷和 P（phyt）利用率，同时减少氮和磷向环境中的排泄。
