Superdosing Phytases in the Diets of Light Laying Hens: Productive Performance and Bone Quality

ABSTRACT Two experiments were carried out with the objective of evaluating the effect of superdosing of two phytases on performance, egg quality, digestive organ biometry and bone quality of light hens in the first (58 weeks) and second (87 weeks) productive cycle. In the first cycle, 270 light hens were used, in which a completely randomized design was adopted in a 2 x 2 + 1 factorial scheme (bacterial phytase or fungal phytase x 450 FTUs or 900 FTUs + control diet). In the second cycle, 270 hens were used, following the same design as the previous experiment. The performance and quality of the eggs were evaluated in both cycles, and the biometry of the digestive organs and bone characteristics were also evaluated in the first experiment. There was no effect in the comparison between the means for the performance and egg quality (in both experiments), or for the biometric variables and bone characteristics (first experiment). There was no significant interaction between the factors for any of the variables in the two experiments. In the first experiment, egg production was higher with bacterial phytase and egg weight with fungal phytase. The mineral matter showed greater value with 450 FTUs. It is recommended to use bacterial phytase produced from Escherichia coli as it improves the performance of light laying hens. The dosage of 450 FTUs improves the mineral content of light laying hens and the use of phytase in the laying hen diet implies a lower feed cost.

摘要
本研究开展两项试验，旨在评估植酸酶（phytase）超剂量添加对产蛋周期第1阶段（58周龄）与第2阶段（87周龄）轻型蛋鸡的生产性能、蛋品质、消化器官形态计量学指标及骨骼品质的影响。
试验1共使用270只轻型蛋鸡，采用2×2+1因子设计的完全随机试验方案，因子设置为：细菌源植酸酶与真菌源植酸酶、450 FTU与900 FTU剂量组，外加1个基础日粮对照组。试验2同样使用270只轻型蛋鸡，采用与试验1一致的试验设计。
两个试验周期均对生产性能与蛋品质进行测定；试验1额外测定了消化器官形态计量学指标与骨骼特性。两项试验中，生产性能与蛋品质指标的组间均值均无显著差异；试验1的消化器官形态计量学指标与骨骼特性指标亦无显著组间差异。两项试验中，各因子间对所有测定指标均未产生显著交互作用。
试验1结果显示，细菌源植酸酶组的产蛋率更高，而真菌源植酸酶组的蛋重更优；450 FTU剂量组的矿物质含量更高。研究建议使用大肠杆菌（Escherichia coli）源细菌植酸酶，其可改善轻型蛋鸡的生产性能。450 FTU的添加剂量可提升轻型蛋鸡的矿物质沉积水平，且在蛋鸡日粮中添加植酸酶可降低饲料成本。