| Popis: |
Two experiments with 90 growing chickens at the age of 30 days: 50 broilers (4 experimental groups and 1 control group) (experiment I), and 40 commercial chickens (3 experimental groups and 1 control group) (experiment II), divided into groups of ten were carried out. The aim of the experiments was to establish the optimal levels of the enzyme phytase in the daily rations of chickens, without disturbing their mineral homeostasis. Different amounts of the enzyme (as the product Natuphos) were added to the chickens’ diet for 60 days. The plasma concentrations of calcium, inorganic phosphate, magnesium, and alkaline phosphatase were studied; also, histological investigations of femoral and tibial specimens on the 30th and 60th day from the start of the treatment were done. We found that, after treatment, the chickens of the two experiments exhibited increased levels of calcium and inorganic phosphate, while the activity of the alkaline phosphatase was significantly lowered. The histological study of femur and tibia showed a thinned compacta and enlargement of the central (Haversian) canals in the broiler chickens at the end of the trials. The results showed that in broiler chickens, phytase supplementation was favourable at 750-1500 FTU/kg food up to the age of 60 days, while for commercial chickens the respective dosage was 1250 FTU/kg food up to the age of 90 days, without addition of dicalcium phosphate. |
