Influence of storage of New Zealand wheats on energy availability for poultry.

Abstract

30A Influence of storage of New Zealand wheats on energy availability for poultry V. Ravindran1, S. Johnston2, B.J. Camden1 and D.V. Thomas 1 1 2 Monogastric Research Centre, Massey University, Palmerston Nor th, New Zealand Tegel Foods, Auckland, New Zealand v. ravindran@massey.ac.nz The `new season grain' phenomenon is a serious practical problem for the poultry industry and has been documented for Australian grains (Choct and Hughes, 1999). This paper presents data on the effects of post_ harvest storage on the apparent metabolizable energy (AME) and apparent ileal digestible energy (AIDE) of wheat and maize grown in New Zealand. Grain samples from five wheat cultivars grown in an area of the South Island and a maize cultivar were collected at harvest (1999/2000 season). Maize from the 1998/1999 season was used as a control. The samples were stored under normal feed mill storage conditions; AME and AIDE assays were made 1 and 3 months post_harvest. Assay diets contained the 95.9% of the test cereal, plus mineral and vitamin supplements, and each was fed to four replicate pens with five 28_day old male broilers per pen. The AME values were determined by the classical total excreta collection method; concentrations of the marker TiO2 in the diets (0.5%) and in ileal digesta enabled calculation of AIDE. The AME of all wheats were improved after 3 months of storage (Table 1); increases ranged from 0.2 to 1.0 MJ/kg dry matter. The AME of maize was unaffected by storage. AIDE were also examined because of possible effects of caecal microflora on excreta_based measurements (Ravindran et al. 1999). The AIDE in the wheat and maize samples ranged from, respectively, 87 to 94% and 104 to 107%, of the corresponding AME. The increases with storage in AIDE in the wheats closely followed the changes in AME, although the increments in AIDE tended to be greater. AIDE of the maize samples was not affected by storage. Choct, M. and Hughes, R. (1999). Effect of storage on the nutritive value of grains for poultry. 11th Australian Poultry and Feed Convention, pp. 233_239; Gold Coast, Qld, Australia. Ravindran, V., Hew, L.I., Ravindran, G. and Bryden, W.L. (1999). A comparison of ileal digesta and excreta analysis for the determination of amino acid digestibility in food ingredients for poultry. British Poultry Science 40, 266_274. Table 1 Changes with storage in apparent metabolizable energy (AME) and apparent ileal digestible energy (AIDE) of New Zealand grains. AME (MJ/kg DM) AIDE (MJ/kg DM) 1 month 12.48 11.90 11.04 11.98 11.52 16.41 16.75 4 months 13.00 12.69 12.73 12.67 12.81 16.53 16.66 Storage Wheat 1 Wheat 2 Wheat 3 Wheat 4 Wheat 5 Maize (new season) Maize (old season) 1 month 13.54 13.20 12.70 13.59 13.00 15.80 15.69 4 months 13.83 13.98 13.72 13.78 13.89 15.72 15.65 Recent Advances in Animal Nutrition in Australia, Volume 13 (2001)