<p>To investigate the breakage characteristics of particle groups, the particle bed compression tests were conducted with feed groups. Three compression stages were determined based on the force–displacement curves of feed pellets with different aspect ratios. The occurrence of the stage ascent curve was explained by the microstructure of the feed pellet and the filling of pores in the particle bed. The influence of aspect ratio and moisture content on the mass-specific compressive energy was investigated, revealing that the energy increased with the increase of aspect ratio and water content. Additionally, the impact of these factors on the pulverization rate was assessed, demonstrating that the pulverization rate rises with the aspect ratio but diminishes with water content. The PSD (particle size distribution) of the feed pellet after compression was fitted with the Weibull function. The R² values are higher than 0.97 and 0.93 for different aspect ratios and water content, respectively. Furthermore, new models were established to represent the PSD, taking aspect ratio and water content into consideration. The R² values are higher than 0.95 and 0.96, respectively. These findings enhance the understanding of breakage characteristics of feed pellets under compression and provide a theoretical model for quality assessment of agricultural products.</p>