The aim of this study was to investigate the effect of starch content and pellet physical quality on the biological response in Atlantic salmon. Salmon feeds with a large variation in physical quality were produced by the adjustment of dietary starch inclusion (92 g kg⁻¹ or 64 g kg⁻¹), preconditioner oil (0.0 or 11.0 kg h⁻¹), extruder moisture addition (13.5 or 27 kg h⁻¹) and drying temperature (38 °C or 70 °C). The variables impacted physical quality for the 12 feed codes and with hardness S (standing) and Durability measured in the range of 39–212 N and 39–94 %, respectively. Gently dried feed (38 °C) was harder and more durable than conventionally dried (70 °C). This could be explained by the phase transition theory and drying in the mobile rubbery phase above the glass transition temperature (T_g) for the gently dried feed codes. All feed codes were evaluated in Atlantic salmon performance and digestibility trials. There was a significant difference between the codes for weight gain (%; P < 0.001), specific and thermal growth rate (P < 0.01) and protein efficiency ratio (P < 0.01). Growth was negatively associated with increased starch content, hardness and durability parameters and reduced solubility, fat content and gross energy. The most important physical properties affecting growth performance were Hardness S, Durability and Doris dust, parameters that may represent feed hydration- and dissolution rates. This study documents that the impact of pellet physical quality should be considered when evaluating the results from biological fish trials.

本研究的目的是研究淀粉含量和颗粒物理质量对大西洋鲑鱼生物反应的影响。通过调整膳食淀粉含量（92 g kg ^-1或 64 g kg ^-1）、预处理油（0.0 或 11.0 kg h ^-1）、挤出机水分添加（13.5 或27 公斤·小时^-1) 和干燥温度（38 °C 或 70 °C）。这些变量影响了 12 种饲料代码的物理质量，硬度 S（站立）和耐久性分别在 39-212 N 和 39-94% 的范围内测量。温和干燥的饲料 (38 °C) 比常规干燥 (70 °C) 更坚硬、更耐用。这可以通过相变理论和高于玻璃化转变温度 (T _{g )}的流动橡胶相中的干燥来解释) 用于轻轻干燥的饲料代码。所有饲料代码都在大西洋鲑鱼性能和消化率试验中进行了评估。增重 (%; P < 0.001)、比和热生长速率 (P < 0.01) 和蛋白质效率比 (P < 0.01) 的代码之间存在显着差异。生长与淀粉含量、硬度和耐久性参数的增加以及溶解度、脂肪含量和总能量的降低呈负相关。影响生长性能的最重要的物理特性是硬度 S、耐久性和 Doris 粉尘，这些参数可能代表饲料水合速率和溶解速率。该研究记录了在评估生物鱼试验结果时应考虑颗粒物理质量的影响。