Sudden death caused by the acute form of gastric ulceration has developed into a widely recognised health and welfare problem. The importance of different triggering factors is poorly understood. The study was carried out on finishers slaughtered in Poland. The collected animal-level data were transformed to a herd-level dataset, which included 27 predictor variables. From a total of 32,264 pig stomachs examined, 23,188 (71.9%) had gastric lesions. Total of 17,703 organs (54.9%) had ulcers. Scores 1 (hyperkeratotic) and 2 (erosions) were observed in 2958 (9.2%) and 2527 (7.8%), respectively. A significant (p < 0.05) association of the ulcer prevalence was found for a number of variables. Raising the level of protein significantly (p = 0.04) increased (ρ = 0.22) the occurrence of gastric ulcers. The addition of wheat bran (p = 0.02) and its growing share in feed composition had the contrary effect (ρ = −0.27). Feeding pelleted feed was significantly associated (p = 0.001) with the higher prevalence of the disease, opposite to liquid feeding (p = 0.0002) and supplementation of a mycotoxin deactivator (p = 0.0008). Although, the immediate transition from one feeding system to another in most of the farms is impossible, the addition of materials such as wheat bran, and routine supplementation with mycotoxin deactivators may be a practical and relatively low-cost solution.