Optimizing laboratory drying protocols for corn silage: Effects of temperature, pre-drying, and freezing on nutrient composition and feeding value

Proper sample preparation is crucial for minimizing analytical errors in silage analysis. This study aimed to optimize laboratory drying protocols and assess the effects of various drying techniques on the chemical composition and feeding value of corn silage. The study design consisted of two experiments. In Experiment 1, samples were dried at 40°C for 60 hours, 55°C for 48 hours, 70°C for 36 hours, and 85°C for 24 hours without pre-drying. "In Experiment 2, samples were subjected to either pre-drying (70°C/80 min, 100°C/60 min, or 130°C/40 min) or freezing (-20°C for 2 months) before being dried at 55°C for 48 h, while the control group (CON) was directly dried at 55°C for 48 h. In Experiment 1, low-temperature drying at 40°C without pre-drying yielded the lowest non-structural carbohydrate levels and the highest structural fiber levels, whereas samples dried at 70°C exhibited the highest values for digestibility and feeding value. In Experiment 2, frozen samples yielded the lowest dry matter, crude protein, and in vitro true dry matter digestibility. Furthermore, pre-drying at high temperatures induced Maillard reactions, which significantly reduced in vitro neutral detergent fiber digestibility. Samples pre-dried at 70°C showed the highest levels of non-structural carbohydrates and nitrogen-free extract, and relative feed value, while yielding the lowest levels of aNDFom and ADF. The control group had the highest in vitro true dry matter digestibility and in vitro neutral detergent fiber digestibility. In conclusion, drying at 70°C without pre-drying can be an effective alternative for preserving nutritional value compared to conventional drying methods. Pre-drying corn silage at 70°C for 80 minutes, followed by conventional drying, can be recommended as a reliable, time-efficient protocol for routine laboratory procedures to ensure accurate nutritional value estimations.