The influence of phosphorus supply on eggshell quality

Abstract

In our study conducted with Tetra SL layer hybrids over a full production cycle (12 months) we aimed to determine how different levels of phosphorus supply influence eggshell quality. The effects of seven treatments were studied during the trials. The trial diets were formulated on a corn-soy basis. Calcium and phosphorus contents were formulated according to the Hungarian practice in the first treatment (A) (3.5 g nonphytate phosphorus/kg); based on the NRC (1994) requirements in the second treatment (B); and based on the findings of the studies conducted by Tossenberger and Babinszky (2008) in the third treatment (C) (38 g calcium /kg, 2 g non-phytate phosphorus/kg). In the fourth treatment (D) the phosphorus content of the diet was reduced by 40 % compared to the NRC (1994) requirement (1.5 g non-phytate phosphorus/kg.) These dietary treatments (A-B-C-D) did not contain phytase supplementation. The basal diet in the fifth, sixth and seventh treatment (E, F, G) was the same as the basal diet of the fourth treatment (D) with the difference, that they were supplemented with a phytase enzyme in the dosage recommended by the manufacturer (E: 450 U Product-1/kg; F:450 U Product-2/kg; G: 450 U Product-3/kg). The trial data were subjected to variance analysis (SAS, 2004). According to our data the 40% lower phosphorus content of the diet (Treatment D) does not reduce eggshell thickness, neither is it affected by the phytase supplementation (Treatments E, F and G). The different phosphorus content of the diets (Treatments A, B, C and D) had a significant influence on eggshell strength (P≤0.05). Product-3 phytase enzyme improved eggshell strength significantly compared to all treatments (P≤0.05). According to the trial results the phosphorus content of layer diets can be substantially reduced beside a concurrent phytase supplementation without any harm to the eggshell quality.