1. This study assessed the impact of drying temperature (54, 90, and 130°C) and maize grain moisture content at harvest (36% and 29%) on in vitro digestibility, the growth performance and ileal digestibility of broiler chickens. 2. In contrast to the results from the in vitro digestibility, apparent ileal digestibility of starch and energy decreased when the drying temperature was raised from 54 to 130°C, and this effect was more pronounced in maize grain harvested at high initial moisture content (36%). Ileal protein digestibility of maize grain decreased significantly when dried at the intermediate temperature (90°C) and with a high harvest moisture content (36%). Drying temperature and initial moisture content did not significantly affect AMEn. 3. When maize was dried at 130°C, the particle sizes of flour recovered after standard milling procedures decreased significantly, which would influence animal growth performance and in vivo digestibility through animal feed selection.

High-Performance Anion-Exchange Chromatography Coupled with Pulsed Amperometric Detection (HPAEC-PAD) was used to quantify and to determine the nature of saccharides released after the digestion of two corn grains submitted to different drying and harvesting protocols. Five saccharides were quantified: glucose, maltose, isomaltose, maltotriose and glucosyl-maltotriose. After a subsequent hydrolysis with amyloglucosidase of the released sugar, the amount of total glucose recovered increased with the increase in drying temperature and the moisture content of grain at harvest. These results suggest that structural changes induced within corn starch granules during drying affect their hydrolysis by amylases. These changes may lead to different pathways of sugar absorption in the small intestine of monogastrics. Thus, corn grains with a similar composition may lead to different levels of metabolizable energy upon gastro-intestinal digestion.

1. The grain drying process may affect the feeding value of maize but until now, no general consensus has been reached. This knowledge is essential to manage maize nutritional value in feed and ensure optimal growth performance of broiler chickens. 2. A total of 72 male Ross 308 were used in a complete randomised block design to assess the effect of initial moisture content (MC) at harvest (high or low MC after the appearance of the black layer) and drying temperature (54°C, 90°C or 125°C) on the apparent faecal digestibility and the AMEn value of two maize grain types (flint and flint-dent varieties). Moreover, the relationship between in vitro dry matter digestibility coefficient (IVDMD) and salt-soluble protein (SSP) content of dried maize grain with AMEn was assessed. 3. High drying temperature (125°C) significantly decreased the AMEn (by 0.41 MJ/kg) of the maize. Maize with high-moisture content at harvest had significantly higher AMEn than maize with low moisture content (0.38 MJ/kg) depending on the variety. Based on the combination of MC at harvest and drying temperature, an AMEn difference of about 0.65 MJ per kg of dry matter was measured during this experiment. The faecal digestibility of starch remained close to 98% with low variation between the treatments. The decrease in AMEn at high drying temperature was related to the decrease in non-starch organic matter retention (NSOM R ). IVDMD and SSP content were not correlated with AMEn of dried maize (R 2 < 0.1). 4. This study showed that using drying temperature below 90°C for maize grain harvested at high MC, just after the black layer development, can enhance its AMEn. The IVDMD and SSP content failed to predict the AMEn of the dried maize, but further research is required to validate the results of this study.