Nutritive value of wheat for broiler chickens; effects of storage time and hemicullulase addition

Abstract

This project set out to test whether there is validity in the hypothesis that the quality of wheat (as judged by its viscosity-inducing properties) for broiler chickens is affected by the time for which it is held in storage. Any interactions between its initial quality (low, medium and high viscosity) and the period of time for which it was stored were also examined.

Three varieties of wheats [Consort (low viscosity), Brigadier (medium viscosity) and Rialto (high viscosity)] were identified and purchased immediately after harvest (31 August 1999). They were monitored after intervals of 1, 9, 17, 25, 33 and 53 weeks in storage (on 7/9/99, 2/11/99, 28/12/99, 22/2/00, 18/4/00 and 5/9/00 for dry matter, oil (B), nitrogen (crude protein) and ash, as well as for specific weight, 1000 grain weight and viscosity of aqueous solutions. Isocaloric and isonitrogenous diets containing the wheats at commercial inclusion rates (605.4 g/kg) were formulated to meet the requirements of broiler chickens and fed to 6 groups of 5 birds for 3 weeks at each of the storage ages. Performance parameters (weight gain, food intake and food conversion efficiency) were monitored and dietary apparent metabolisable energy (AMEN) values derived. True metabolisable energy (TMEN) values of these diets and the individual wheats were determined at the same time and with identical birds of the same age. The effects of the addition to the diets of a commercial hemicellulase (Avizyme 1300) were also evaluated simultaneously.