Liver lipid content of twenty varieties of laying hens from three confinement systems

Average liver lipid values were determined for 20 varieties of 71-week old laying hens managed in 3 confinement systems of the 1972-73 North Carolina Random Sample Laying Test. There were highly significant differences in liver lipid atrributable to variety, to confinement system, and a significant variety X system interaction. Four varieties had consistently high and five had consistently low liver lipid values in all 3 confinement systems. Varietymeans ranged from 25.8 to 49.0% liver lipid on a dry weight basis. Hens confined 2/cage had slight but significantly higher liver lipid than hens 7/cage or in floor pens. Liver lipid was positively correlated with body weight in hens 2/cage and in floor pens. There were no significant correlations of liver lipid with egg production or mortality. A frequency distribution of individual liver lipid values revealed a continuous distribution from 15.4 to 65.4with a pronounced skew to the right of the mean of 38.2%. Neither a fatty liver syndrome nor liver hemorrhage syndrome was reported for any of the flocks during the laying year. The normal range of liver lipid values for hens 71 weeks of age appears to be between 25 and 49 g. of lipid per 100 g. of dry liver weight.