Poljoprivreda (Jun 2007)
IMPACT OF PHYTASE SUPPLEMENTATION ON THE CALCIUM AND PHOSPHOROUS RETENTION IN HIGH PRODUCING LAYERS
Abstract
The calcium and phosphorous retention of layers was evaluated at different production levels (45 - 75 - 95 % of final production peak) with Hy-Line Brown hybrid layers during the first twelve weeks of the laying cycle. 32 layers evenly distributed over 4 treatments (Trts). The Ca content of the diets was identical across all Trts (32,5 g/kg), while P contents and phytase activities differed. In the first Trt the P content of the diet was 2.5 g/kg non-phytate P, without any phytase added. In the second Trt the P content of the diet was reduced by 40 % compared to Trt 1 (1.5 g/kg non-phytate P) without phytase supplementation. In the third and fourth Trts the P content of the diets was the same as in 2 (1.5 g/kg non-phytate P) but the diets were supplemented with phytase (3-phytase produced by trichoderma reesei) at a rate of 250 PPU/kg (Trt 3) and 500 PPU/kg (Trt 4), respectively. According to the results the different P content of the diets affected (P≤0.05) the rate of Ca retention at all trial phases. In the case of reduced P level diets the different phytase inclusion rates did not influence the amount of Ca retained by the birds (P≥0.05). Within the same Trt Ca retention increased (P≤0.05) with increased production intensity. At reduced P content phytase improved (P≤0.05) the P retention of the layers at all trial phases. There was no difference between both phytase application rates. As a result of phytase supplementation P retention reached the P retention of positive control birds (Trt 1) in all trial phases.
