Recent studies have suggested that phytase enzymes may influence sodium (Na) metabolism in the chick. However, no studies have demonstrated that the dietary sodium requirement itself is influenced by phytase supplementation, according to S.D. Goodgame and colleagues at the University of Arkansas in their paper in the International Journal of Poultry Science.

In their study, male broilers were fed diets with sodium levels ranging from 0.10 to 0.28 per cent using sodium chloride as the source of supplemental sodium. Diets were fed either without phytase or with 500 (1X), 1,000 (2X) or 2,000 (4X) FTU per kg of phytase. For 1X phytase, the calcium and non-phytate phosphorus (NPP) were reduced 0.10 per cent each and 0.20 per cent each for the 2X and 3X levels of phytase supplementation.

The diets with 0.10 per cent and 0.28 per cent sodium were blended to provide sodium levels of 0.10, 0.13, 0.16, 0.19, 0.22, 0.25 and 0.28 per cent sodium. Aliquots of these diets were then supplemented with the 0, 1X, 2X and 4X levels of phytase in a 4×7 factorial arrangement of treatments, each of which was fed to six replicate pens of five male broilers in electrically heated battery brooders.

Experimental diets and tap water were provided for ad libitum consumption from day of hatch to 18 days of age. At 16 days, excreta samples from each pen were freeze dried to determine moisture, calcium and phosphorus content.

At 18 days, body weight and feed consumption were determined. Two birds per pen were killed by carbon dioxide inhalation and tibias removed and subjected to bone breaking determination.

Chicks fed diets with the different levels of phytase with diets adjusted for anticipated release of calcium and phosphorus did not differ significantly in bodyweight, feed conversion ratio (FCR), mortality, or faecal moisture content, indicating that the adjustments made for anticipated release of calcium and phosphorus was adequate in relation to these measurements.

Sodium levels of the diet had significant effects on bodyweight, FCR and faecal moisture. Faecal moisture increased with each level of sodium, so lower dietary levels would be beneficial in this regard.

No significant effects on mortality were noted for sodium levels.

No significant interactions were noted between sodium level and phytase supplementation for bodyweight, FCR, faecal moisture or mortality. Regression analyses suggested a sodium requirement of 0.21±0.02 per cent for bodyweight and 0.15±0.01 per cent for FCR.

Estimates of sodium requirement at different levels of phytase supplementation did not show any consistent effect of phytase supplementation on the sodium requirement for bodyweight or FCR, concluded Goodgame and colleagues, adding that there is no evidence that phytase supplementation will modify the dietary sodium requirement of the broiler chick.

Reference

Goodgame S.D., F.J. Mussini, C. Lu, C.D. Bradley, N. Comert and P.W. Waldroup. 2011. Effect of phytase on the sodium requirement of starting broilers. 2. Sodium chloride as sodium source. International Journal of Poultry Science, 10(10): 766-773.

Further Reading

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January 2012