Factors Influencing the Liver Fat Content of Laying Hens

Abstract

An incidence of mortality from hemorrhage in fatty livers of Cornell experimental flocks is described. Hens fed diets varying in energy or protein content showed a wide range in liver fat content when sampled at various times during the laying year. The ability of individual hens to adjust to changes in energy concentration of the diet was not correlated with liver fat content. In hens fed specific diets, liver fat was not correlated with energy intake or rate of egg production. Feeding a low energy diet for 21 days caused a reduction in liver fat, compared to that in hens fed a control diet. However, when the hens were returned to the control diet, liver fat quickly returned to the level found in hens fed the control diet continuously. When hens were force fed 10% more feed than ad libitum controls consumed, marked increases in liver size and fat content occurred, but no mortality was observed from liver hemorrhages. Fatty livers had a higher content of neutral lipid, mainly triglyceride, than livers lower in fat. The content of oleic acid increased and linoleic acid decreased as liver fat increased. This suggests that fatty acid biosynthesis is the major source of the lipid in fatty livers. These studies showed that liver fat content of hens is variable and that high levels of liver fat are not necessarily detrimental to laying performance. Hemorrhages from fatty livers may be related to other factors than liver fat content per se.