Effects of microbial phytase, produced by solid-state fermentation, on the performance and nutrient utilisation of broilers fed maize- and wheat-based diets

Abstract

1. The influence of a microbial phytase on the performance, toe ash contents and nutrient utilisation of male broilers fed diets based on maize and wheat was investigated. The experiment was conducted as 2 × 2 × 2 factorial arrangement of treatments. Within the factorial, two diet types (maize–soy or wheat–soy) containing two levels of non-phytate phosphorus (3·0 or 4·5 g/kg) were evaluated and each level of non-phytate phosphorus was supplemented with 0 or 500 PU phytase/kg diet. Each of the 8 dietary treatments were fed to 6 pens of 8 birds from d 1 to 21 post-hatching.

2. Main effects of diet type and phytase were observed for all parameters. Main effect of non-phytate phosphorus was significant only for feed/gain and toe ash contents. Phytase addition improved weight gains irrespective of diet type or non-phytate phosphorus level, but the magnitude of improvement in the phosphorus-deficient wheat–soy diet was greater, resulting in a diet type × non-phytate phosphorus interaction. Responses in toe ash contents were noted only in phosphorus-deficient diets, as indicated by a non-phytate phosphorus × phytase interaction.

3. Phytase addition improved apparent metabolisable energy values of wheat-based diets, but had little effect on the apparent metabolisable energy of maize-based diets as shown by a diet type × phytase interaction. The apparent metabolisable energy was not influenced by dietary non-phytate P.

4. Phytase improved ileal nitrogen digestibility in both diet types, but the responses to added phytase tended to be higher in wheat-based diets, as shown by a diet type × phytase interaction.

5. Increasing the dietary non-phytate phosphorus level reduced phosphorus digestibility and increased excreta phosphorus content. Addition of phytase improved phosphorus digestibility, but the increments were higher in low phosphorus diets resulting in a non-phytate phosphorus × phytase interaction. Phytase addition tended to lower the excreta phosphorus content, but the effects were greater in birds fed low phosphorus diets, as shown by a non-phytate phosphorus × phytase interaction.

Notes

¹Zero or 500 PU of phytase was added to each of the diets.

²Poultry mineral 4 (Tegel Foods Ltd, Auckland, New Zealand). Supplied per kg diet: Mn 125 mg, Zn 60 mg, Cu 3 mg, Mo 0·5 mg, Co 0·3 mg, I 1 mg, Fe 25 mg, Se 200 µg, choline chloride 638 mg.

³Broiler starter vitamin (Tegel Foods Ltd, Auckland, New Zealand). Supplied per kg diet: trans-retinol 3·33 mg, cholecalciferol 60 µg, dl-α-tocopheryl acetate 60 mg, menadione 4 mg, thiamine 3·0 mg, riboflavin 12 mg, calcium pantothenate 12·8 mg, niacin 35 mg, pyridoxine 10 mg, folic acid 5·2 mg, cyanocobalamin 0·017 mg, biotin 0·2 mg, antioxidant 100 mg.

¹Without or with the addition of 500 PU/kg diet.

²Means are based on 6 pens of 8 birds each per treatment group.

³Each main effect mean is based on 24 pens of 8 birds each.

¹Without or with the addition of 500 PU/kg diet.

²Means are based on 6 pens of 8 birds each per treatment group.

³Each main effect mean is based on 24 pens of 8 birds each.