Heat-stable phytase enzyme in on growth performance in broiler chickens

An experiment was conducted at Research & Development Centre, Islamabad Feed Mills, Rawat, Pakistan, from July 26 to September 01, 2007.

The trial used 4,356 day old broiler chicks and was conducted to 35 days of age to determine bio-efficacy of a phytase enzyme (Phyzyme XP 10000 TPT, Danisco) on the growth performance of broiler chicks.

Eight treatment diets were prepared as follows:

     1. Without DCP&MCP and no phytase supplementation
     2. Without DCP&MCP and 50 g/tonne phytase supplementation
     3. With 25% DCP&MCP and no phytase supplementation
     4. With 25% DCP&MCP and 50 g/tonne phytase supplementation
     5. With 50% DCP&MCP and no phytase supplementation
     6. With 50% DCP&MCP and 50 g/tonne phytase supplementation
     7. With reduced DCP&MCP and 50 g/tonne phytase supplementation and with use of matrix values
     8. Positive Control diet

All the ingredients used and diets prepared were analyzed for total phosphorus (P). Total P in the control feed was 0.75 and 0.72% for starter and finisher diets respectively and lower in other diets with the reduction in inclusion level of DCP&MCP.

Total P in starter and finisher diets without DCP&MCP supplementation was 0:55 and 0.51%, respectively.

The phytase was added in premix and feed processed in a commercial pelleting mill closely monitored at 90-95 °C conditioning temperature.

There were 36 replicate floor pens with 121 chicks per pen and assigned to eight dietary treatments with 4 or 5 replicates per treatment, at random. Broiler strain used was Hubbard. Daily feed intake, weekly body weight per pen and mortality were recorded and feed: gain ratio was calculated.

Commercial broiler feed served as positive control diet. In other diets supplementation of DCP and MCP was reduced to zero, 25% and 50 % of the amounts in the positive control with and without phytase during starter and finisher phases.

Composition of the starter feeds used from 1-28 days is shown in table 1. Finisher diets similar in composition were used for the period 29-35 days (not shown).

Results

Results for weight gain, feed intake, mortality and feed:gain ratio are summarized in table 2. In all cases, the addition of phytase improved growth performance by broiler chicks. For the first 6 treatments, addition of the phytase improved weight gains, feed intake and feed:gain.

With 50% replacement of the DCP&MCP, phytase addition of 500 FTU/kg feed gave weight gain, feed intake and feed:gain equal to the positive control feed.

Use of matrix values for Calcium and available P, as suggested by the phytase manufacturer, also gave performance equal to the positive control treatment.

Table 1. Composition of starter feeds

Bio-Efficacy of a heat-stable phytase enzyme in pelleted feed on growth performance in broiler chickens - Image 1

Bio-Efficacy of a heat-stable phytase enzyme in pelleted feed on growth performance in broiler chickens - Image 1

Table 2. Effects of treatments on broiler performance (1-35 days)

Bio-Efficacy of a heat-stable phytase enzyme in pelleted feed on growth performance in broiler chickens - Image 2

Bio-Efficacy of a heat-stable phytase enzyme in pelleted feed on growth performance in broiler chickens - Image 2

¹ Matrix values were …
² 50 g/tonne feed (500 FTU/kg feed)
³ Corrected for mortality

Conclusions

From the performance results of this trial, this particular phytase appears to be stable under the pelleting conditions used.

The phytase used gave improved weight gains, feed intake and feed:gain when added to P reduced diets.

Two treatments in particular would appear to be worth considering for commercial use. This is replacement of 50% of the inorganic P in the diet, or by reducing Calcium and Phosphorus according to the recommendations of the manufacturer.

About the Author:

Dr. Munawar Ali is General Manager of Islamabad Farms, Pakistan. He is responsible for broiler breeder management and poultry feed formulation and has 29 years practical experience.