The effect of conditioning temperature and exogenous xylanase addition on the viscosity of wheat-based diets and the performance of broiler chickens

Abstract

1. A total of 1920 Ross broiler chicks were used in a 6 treatment by 8 replicate growth study to investigate the effect of conditioning temperature and exogenous xylanase addition on diet characteristics and bird performance.

2. Increasing conditioning temperature from 80 to 90°C increased the viscosity of the diets by approximately 6 mPa.s and reduced body weight gain of the broiler chickens by 7%.

3. Furthermore, there was a significant interaction between temperature and the addition of exogenous xylanase, with a proportionately greater positive response to added xylanase in the diets that were pelleted at higher temperatures.

4. Addition of exogenous xylanase also increased the proportion of soluble arabinoxylan in the feed and reduced dietary viscosity, which is likely to be related to the degree of polymerisation of the soluble carbohydrate.

5. These results suggest that conditioning temperature should be considered as a factor when attempting to predict the response of broilers to added xylanase, especially when high-viscosity or ‘low-quality’ wheat is being used.

6. It can be concluded that pelleting wheat-based diets above 80°C can compromise bird performance and that, if higher temperatures are to be employed, the use of exogenous xylanase is critical to maintain productivity.

Acknowledgements

The authors gratefully acknowledge the technical expertise of staff at Roslin Nutrition Ltd, who carried out the experimental part of this research, and also staff at Danisco Innovation, who were responsible for the laboratory analyses. This work was supported financially by Danisco Animal Nutrition.