Differential influence of phytase supplementation on the balance of phosphorus and other elements in laying hens' feed

The aim of this study was to evaluate the impact of microbial phytase addition to laying hen diet on the balance of phosphorus, calcium, manganese and zinc. Phytase supplementation caused a decrease in phosphorus excretion by 8% in the group with low-phytase diet and 21% in the group with phytase addition of 1000 FTU (one unit of phytase activity) to a diet. Phytase supplementation increased the retention of phosphorus by 31% in laying hens receiving 500 FTU and 57% in the group with phytase addition of 1000 FTU to a diet, in comparison to the group without enzyme supplementation. The level of manganese in excretion was increased by 18% in the group receiving 1000 FTU phytase, and retention decreased by 24% compared with the control group. Zinc excretion was significantly increased in the group receiving 500 FTU (P È 0.01) and in the group receiving 1000 FTU phytase (P È 0.05). Retention of zinc was lower (P È 0.01) when the birds were fed with feed containing 500 FTU and 1000 FTU phytase (P È 0.05), compared with the control group. No effect on the quantity and retention of calcium excretion was found. There was no impact of phytase supplementation on egg production and egg weight.