The effects of dietary intake and of dietary concentration of copper sulphate on the laying domestic fowl: Effects on some aspects of lipid,carbohydrate and amino acid metabolism

1. These investigations were carried out to determine whether the effects of feeding CuSO₄‐supplemented diets on metabolism in the laying hen were due directly to the dietary CuSO₄ content or indirectly to the effects of CuSO₄ on food consumption.

2. In experiment 1, 144 hens were given GuSO₄‐supplemented diets ad libitum for 48 d. Food consumption decreased as the dietary CuSO₄ content increased and this was associated with decreases in blood plasma lipid, 17β‐oestradiol and liver lipid concentrations and hepatic lipogenic enzyme activities.

3. In experiment 2, 60 laying hens were subjected to three dietary regimens in an attempt to differentiate between the effects of reduced food consumption and dietary CuSO₄ per se. Control and CuSO₄‐supplemented diets were fed ad libitum, or the CuSO₄‐containing diets were force‐fed to the same intake as the ad libitum control diet, or the control diet was pair‐fed to the same intakes as the CuSO₄‐supplemented diets. Liver lipid concentrations were significantly decreased in the ad libitum and pair‐fed groups at the lowest intake. Plasma 17β‐oestradiol concentration was decreased in ad libitum and force‐fed birds given diets with 1 000 mg added Cu/kg. Lipogenic enzyme activities were reduced in the ad libitum and pair‐fed groups and increased in the force‐fed birds.

4. The results indicate that CuSO₄ per se directly affected circulating 17β‐oestradiol, and hence reproductive physiology, and that the quantity of food consumed influenced the rate of hepatic lipogenesis.