Liver Damage and Supplemental Methionine Sources in the Diets of Mature Laying Hens

Several commercial laying flocks with higher than normal mortality during 1992 exhibited liver pathology of unknown origin. Prior to death, the birds exhibited signs such as pale skin and poor egg production. Although the condition had been observed in birds fed supplemental 2-hydroxy-4-(methylthio) butanoic acid (HMB, Alimet Feed Supplement) and DL-methionine (DLM), analog toxicity was suggested as a possible etiology. A performance study attempted to clarify whether high levels of the supplemental methionine sources could play any role in the observed liver pathology. This study was conducted in cooperation with R. Wideman at Pennsylvania State University. Performance results appear in a separate report. Histopathology results presented here indicate no significant effect of high levels of either HMB or DL on incidence of inflammation, fatty liver, hemorrhage, fibrosis, or extracellular iron when compared to birds fed a control diet. Tissue samples from the experimental birds were compared with those taken from a commercial flock exhibiting mortality to clarify differences in histopathology. Results indicated that the commercial birds were affected by a granulomatous disease, most likely of infectious origin. Conversely, birds on the experimental diets showed no evidence of chronic hepatitis.