| Abstract: | Lipid content of the liver and its lipogenic activities were compared among year-old laying hens and hereditary non-layers and roosters fed a low-fat and cholesterol-free grain diet. In contents of free cholesterol, cholesteryl ester and phospholipid, the differences between groups were relatively minor, but striking differences were noted in triglyceride with a marked accumulation in non-layers. Incorporation studies of 14C]acetate and 14C]mevalonate by liver slices revealed that in layers, acetate was preferentially incorporated into saponifiable lipids (SF), whereas mevalonate incorporated actively into both saponifiable and non-saponifiable (NSF) lipids. Lipid synthesis with acetate and mevalonate was extremely low in non-layers; in roosters, utilization of acetate was very poor but mevalonate was actively incorporated into SF and NSF lipids. During incubation of tissue slices, acetate was extensively oxidized to CO2, whereas mevalonate was poorly oxidized in all chickens. The level of substrate oxidation was similar between layers and roosters, but their level of oxidation was much greater than that of non-layers. |
