Effects of phosphorolytic and cell wall-degrading enzymes on the performance of growing broilers fed wheat-based diets containing different calcium levels

Abstract

A study was conducted to determine the cumulative effects of phosphorolytic enzymes, cell wall-degrading enzymes, and citric acid and Ca levels on feed intake, BW gain (BWG), feed conversion, intestinal viscosity, and toe ash of broilers (d 1 to 21) fed wheat-based diets. Broilers were fed the following six diets at either 0.59, 0.69, or 0.79% Ca: 1) a negative control (NC) diet, 0.17% available P; 2) NC + 750 phytase units/kg diet; (3) phytase + 3,156 units of acid phosphatase/kg diet; 4) phytase + acid phosphatase + 1,900 units of pectinase/g diet; 5) phytase + acid phosphatase + pectinase + 3% citric acid; and (6) NC plus 0.24% available P. The 18 dietary treatments were fed to four pen replicates of eight birds each. Phytase addition at the low Ca level increased BWG, improved feed intake and conversion and toe ash, and reduced intestinal viscosity and ileal length. Subsequent addition of acid phosphatase, at 0.69% Ca, resulted in increases in BWG, 42%; feed intake 32%; feed conversion 7.5%; and toe ash, 63% over the NC diet. Pectinase addition produced further improvements in 21-d BWG and feed intake at 0.59 and 0.79% Ca, increased toe ash in chicks fed 0.79% Ca, and reduced intestinal viscosity. Supplementation of wheat-based 0.17% available P diets with phytase and acid phosphatase and with appropriate concentrations of pectinase, citric acid, and Ca significantly improved BWG, feed intake and conversion and intestinal viscosity over the 0.41% available P diets. Bone mineralization of chicks fed phytase + acid phosphatase and 0.69% Ca and those fed phytase + acid phosphatase + pectinase + citric acid and 0.59% Ca was similar to that of chicks fed the 0.41% available P diets.