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Salmonella Feed Treatments Do Not Reduce Phytase Efficacy

20 June 2013

BRAZIL - Formaldehyde-based additives, used to control Salmonella in feed, reduce the activity of phytase in feed but do not affect its efficacy in broilers, report researchers.

The inclusion of formaldehyde-based additives (FBA) may negatively affect phytase activity recovered in the feed but has no effect on phytase effectiveness in vivo, according to researchers based at the University of São Paulo.

In a paper published in Journal of Applied Poultry Research, Tiago dos Santos of AB Vista Feed Ingredients in the UK and co-authors at the University in Brazil explain that phytase and FBA are routinely used in broiler nutrition. Phytases hydrolyse phytate, the storage form of phosphorus in plants, making organic sources of phosphorus more digestible by poultry; FBA are also used to decrease the incidence of Salmonella contamination in feeds.

Though phytase activity recovered in the feed is the most common way to measure dietary phytase inclusion, FBA reduce the analysed phytase activity in the feed.

The objective of their trial was to evaluate the effect of a FBA on the efficiency of phytase in broilers.

Day-old chicks (n=630) were allocated to 14 treatments in a 7 × 2 factorial arrangement of treatments consisting of a positive control formulated to meet nutrient requirements or a negative control with reduced available phosphorus and calcium. The negative control diet was supplemented with five different phytases according to supplier recommendations (enhanced Escherichia coli Quantum phytase at 500U per kg; wild-type E. coli Finase EC at 500U per kg; fungal Finase P at 500U per kg; coated fungal Ronozyme NP at 1,500U per kg; and a coated wild-type E.coli Phyzyme TPT at 500U per kg) with or without inclusion of an FBA (Salmex, 3kg per tonne) with five replicates per treatment and nine birds per replicate.

On day 20, animal performance was determined by feed intake and bodyweight gain and mortality-corrected feed conversion was calculated.

All birds were euthanised and left tibias were collected and weighed for ash and determination of calcium and phosphorus.

Dos Santos and co-authors found analysed phytase activity of the feeds containing an enhanced E. coli and a wild-type E. coli to be reduced with FBA inclusion. Body weight gain and tibia weight, ash, ash concentration, ash Ca and P, and P concentration were reduced when animals were fed a low-available phosphorus diet. However, phytase supplementation improved all these response variables, regardless of FBA inclusion.


dos Santos T.T., G.A. Gomes, C.L. Walk, B.V. Freitas and L.F. Araujo. 2013. Effect of formaldehyde inclusion on phytase efficiency in broilers. J. Appl. Poult. Res. 22(2) 204-210. doi: 10.3382/japr.2012-00594

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