Lipid metabolism in the fowl under normal and abnormal circumstances.

Normal metabolism Like the mammal, the fowl utilizes fat as its main energy store, taking advantage of the high energy value of fat compared with that of carbohydrate or protein, and its low water content. The lipids present in these species are similar in nature and composition and there appear to be no gross differences in the pathways by which they are metabolized or in the biochemical mechanisms involved (Annison, 1971 ; Pearce, 1974). The differences which do exist are quantitative rather than qualitative and are expressed physiologically. Absorption and transport. When a commercial diet is given, the fatty acids and glycerides present in the fowl are derived largely from dietary carbohydrates. However, this type of diet is not obligatory for the chick, and fat can be used to supply over 90% of the ‘carbohydrate’ energy without affecting growth (Renner, 1964). In the laying hen gluconeogenesis does not appear to be adequate under these Circumstances, and egg production and hatchability are reduced (Roland & Edwards,