Effects of dietary propionic acid, sodium citrate, and phytase on growth performance, mineral digestibility, and tibia properties in broilers

Combination of phytase and citric acid, but not phytase alone, ensures regular rates of growth and bone mineralization in quails under severe phosphorus restriction

An experiment was conducted to evaluate the effects of phytase (PHY), alone or in combination with citric acid (CA), on growing Japanese quails under moderate and severe phosphorus (P) restriction. For this, 504 one-day-old female quails were distributed in a completely randomised design with seven treatments and six replications. Treatments consisted of the following diets: (a) positive control (PC): formulated according to quails nutritional requirements; (b) negative control 40% (NC₄₀ ): PC with 40% less aP; (c) NC₄₀ +PHY; (d) NC₄₀ +PHY+CA; (e) negative control 65% (NC₆₅ ): PC with 65% less aP; (f) NC₆₅ +PHY; (g) NC₆₅ +PHY+CA. Phytase and CA were included at 300 FTU/kg and 40 g/kg, respectively. Performance, bone mineralization and plasma mineral concentration were evaluated at day 35; calcium (Ca) and P metabolism, between days 36 and 39. No significant differences in performance, plasma Ca and P were detected between quails fed PC or NC₄₀ ; however, NC₄₀ decreased tibia ash (p < 0.01). Treatment NC₆₅ impaired daily weight gain (p = 0.01), tibia ash (p < 0.01), and tibia optical densitometry (p = 0.03), as well as modified plasma Ca (p < 0.01) and P (p = 0.03) concentrations when compared to PC. Both NC₄₀ and NC₆₅ reduced P excretion (p < 0.01). Phytase alone restored tibia ash of NC₄₀ quails to regular rates. Nevertheless, only PHY and CA combined returned plasma P, tibia ash, tibia optical densitometry, and daily weight gain of quails fed NC₆₅ to similar values as those observed in PC. In conclusion, PHY alone suppresses the negative effects of moderate P restriction in growing Japanese quails, but fails in this task under severe P restriction. In such a situation, only the combination of PHY and CA ensures regular rates of growth and bone mineralization. This concept should be better explored by producers in order to take full advantage of the reduction in P excretion achieved by lowering dietary P concentrations.

Effect of immobilized fungal phytase on growth performance and bone traits of broilers fed with low dietary calcium and phosphorus

AIM

The aim of this study was to investigate the effects of phytase which was laboratory produced by Aspergillus foetidus on the growth performance, mineral retention, and bone traits of broilers fed with low dietary calcium and phosphorus.

MATERIALS AND METHODS

The extracellular phytase enzyme secreted into the crude filtrate was concentrated by ammonium sulfate precipitation to obtain an activity of 500 phytase units (FTU). A total of 90 1-day-old chicks (Cobb 500) were randomly divided into three treatment groups with five replicates having six birds each. Dietary treatment, T1, was with 0.45% non-phytate P (NPP) during starter and 0.40% during finisher phase with 1% Ca. Dietary treatment, T2, had 0.37% NPP during starter and 0.32% in finisher phase with 1% Ca and supplemental lab phytase at 500 FTU/kg. Dietary treatment, T3, was similar to T2 with a lower Ca of 0.8%.

RESULTS

There was no significant difference among the dietary treatments with regard to body weight gain, feed intake, feed conversion ratio, and Ca retention (p>0.05). However, a significant improvement in retention of P by birds was observed in phytase supplemental groups T2 and T3 (p<0.05). Dry weight of tibia (2.58-2.78 g/kg live weight) and ash content (39.7-41.8%) was comparable among treatments. A similar trend was observed for bone Ca, P, and Mn content.

CONCLUSION

The study indicated that 500 FTU/kg phytase can be effectively supplemented in a broiler diet with low phosphorus (0.37% in starter and 0.32% NPP in finisher diet) and low calcium (0.8% in diet) for better growth performance and with successful replacement of dietary P by 0.08 % and reduced P excretion into the environment in broiler chicken.