An experiment with 96 male broiler chickens (hybrid ROSS 308), distributed in 3 groups, 32 chickens each, was conducted. Each group consisted of
4 subgroups, 8 chickens each. Live weight, the retention of nitrogen, calcium and phosphorus in the chickens’ organisms were monitored at the age of 1, 11, 29
и 42 days. The birds received 3 types of compound feed. The control group birds were fed a maize-soybean diet without phytase and the birds from the
experimental groups were fed a diet, supplemented by Natuphos 5000G or Optiphos phytase. Diets for all growing periods were balanced as to CP, Ca and
available phosphorus. In the phytase groups the total phosphorus quantity was decreased from 0.81% to 0.66% for the starter period, from 0.76 to 0.61% for
the grower one and from 0.72% to 0.56% for the finisher period. The obtained results showed that phytase supplementation to the maize-soybean diet
improved the utilization of nitrogen, calcium and phosphorus and the tibia ash quantity in broiler chickens during the 0-42–day-period. For the whole fattening
period broilers fed maize-soybean diets supplemented by Natuphos or Feedophyt phytase had a reliably higher live weight by 10.95% and 11.93%,
respectively, in comparison with the group without phytase. The forage consumption for 1 kg weight gain in chickens decreased by 17.02% (p ≤ 0.01) on
average as a result of the use of exogenous phytase. By supplementing phytase to a maize-soybean diet the quantity of dicalcium phosphate decreased by
34% (0-42 days) thus reducing the price of compound forage.

Comparison of the effects of Natuphos® 5 000 G and Optiphos® phytases utilization in broiler chicken feeding with maize-soybean diets

P. Valkova