Effects of feed restriction on growth and metabolism of replacement pullets

The effects of feed restriction on lipogenesis, carcass composition, and protein utilization were investigated. Two feed restriction programs were used: restricted duration of feeding (RDF) whereby pullets had access to feed for 7 or 9 hr/day and restricted access to feed (ADF) in which feed was available on alternate days. A control group received the same diet as the restricted groups but on an ad libitum basis. The feeding programs were applied to a white egg and brown egg strain of commercial laying hens from 1 until 5 weeks of age or from 3 days (RDF) or 10 weeks (ADF) until 19 weeks of age. The ADF restriction resulted in 12 to 25% decrease in body weights at 5 weeks and 5 to 11% decrease in body weights at 18 or 19 weeks. The RDF depressed body weights 24% at 5 weeks and 2% at 18 weeks. The RDF and ADF increased hepatic malic enzyme and glutamic oxaloacetic transaminase activities in both age groups. Plasma uric acid and hepatic glutamic pyruvic transaminase were affected, but not consistently, by ADF. It is hypothesized that ADF and RDF lead to increased lipogenesis and increased utilization of amino acids as sources of energy. Under conditions of mild restriction, this may result in increased carcass fat content.