Lipid metabolism of Tsaiya ducks: plasma and liver related traits under adlibitum and fasting

This study investigated related traits of lipid metabolism in plasma and li ver of layer Tsaiya ducks. Each of 60 ducks was randomly allocated into an ad libitum feeding and a three-day fasting group during the growing period (8-12 weeks old) and during the initial laying period (26-30 weeks old; 10- 14 weeks from the onset of laying), respectively. Results indicated that, e ven under ad libitum conditions, Tsaiya ducks had high concentrations of pl asma glycerol and ketone bodies. Plasma triacylglycerol (TG) contents of la ying ducks were approximately seven-fold higher than those of growing ducks . Contents of liver fat and ketone bodies, plasma phospholipid and non-este rified fatty acid (NEFA) concentrations were higher in the laying period th an in the growing period. The lipogenesis-related traits, including blood g lucose, plasma TG and phospholipid concentrations, were significantly decre ased by fasting (P < 0.05). In contrast, the lipolysis-related traits, incl uding plasma NEFA, glycerol and ketone body concentrations, were significan tly increased by fasting (P <0.05). After fasting, body and liver weights o f ducks and contents of abdominal fat and liver TG were significantly decre ased (P <0.05); conversely, concentrations of liver ketone bodies were mark edly increased (P < 0.05). This study indicated that fasting depressed lipo genesis and increased lipolysis in Tsaiya ducks. In addition, in laying duc ks, lipogenesis was more active than in the growing ducks. (C) 1999 Society of Chemical Industry.