The excretion of Ca, Mg, Zn and Cu via excreta of laying hens fed low phosphorus diets and phytase
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An 8 – week experiment was conducted to study the effect of adding phytase (Natuphos ® 5000 BASF) to low and normal available phosph orus diets of laying hens on the excreta content and excretion of Ca, Mg, Zn and Cu. A total of 144 Hisex Brown laying hens that were 22 weeks old at the start of the experiment were randomly assigned to four dietary treatments. Treatments included three r eplicates (12 hens each) or 36 hens per treatment in total. Four corn - soybean meal - based diets were formulated to contain two levels of available phosphorus (AP; 0.12 and 0.46%) and two phytase levels (0 and 600 FTU kg – 1 ). The results showed that there was no significant effect of added phytase on excreta Ca and Mg content ( P > 0.05), but there was a significant effect of the dietary treatment on the content of Zn ( P = 0.0075) and Cu ( P = 0.0002). In terms of the excretion of these mine rals, the dietary treatment had no effect on Ca and Zn excretion and a borderline effect ( P = 0.0522) on Mg excretion measured as the amount of the mineral excreted per egg mass produced is observed. The results however showed a very strong effect of all three factors (available phosphorus, phytase and their interaction) on Cu excretion. The r esults indicate that adding 600 FTU to the corn - soybean meal laying hen diet with 0.12% or 0.46% AP beneficially affects the content and the excretion of Ca, Mg, Zn and Cu. Therefore, we can conclude that a laying hen diet containing 0.12% available phosphorus and 600 FTU during the first production cycle may not only satisfactorily support hens’ perf ormance but will also beneficially affect the environment.