ABSTRACT

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 (R² < 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.

摘要

1. 谷物干燥过程可能会影响玉米的饲用价值，但目前尚未达成普遍共识。这些知识对于管理饲料中的玉米营养价值和确保肉鸡的最佳生长性能至关重要。

2. 总共 72 只雄性 Ross 308 被用于完全随机区组设计，以评估收获时初始水分含量 (MC)（黑色层出现后的高或低 MC）和干燥温度（54°C）的影响, 90°C 或 125°C) 对两种玉米谷物类型（燧石和燧石品种）的粪便表观消化率和 AMEn 值的影响。此外，评估了玉米干粒体外干物质消化率（IVDMD）和盐溶蛋白（SSP）含量与AMEn的关系。

3. 较高的干燥温度（125°C）显着降低了玉米的AMEn（降低了0.41 MJ/kg）。收获时水分含量高的玉米的 AMEn 显着高于水分含量低的玉米（0.38 MJ/kg），具体取决于品种。基于收获温度和干燥温度下 MC 的组合，在该实验期间测量到每公斤干物质的 AMEn 差异约为 0.65 MJ。淀粉的粪便消化率保持在接近 98%，处理之间的差异很小。在高干燥温度下，AMEn 的降低与非淀粉有机物保留 (NSOM _R ) 的降低有关。IVDMD和SSP含量与干玉米的AMEn不相关（R ²  < 0.1）。

4.本研究表明，在黑层发育后，高MC收获的玉米籽粒在90℃以下干燥温度可以提高其AMEn。IVDMD和SSP含量未能预测干燥玉米的AMEn，但需要进一步的研究来验证本研究的结果。