Effect of residual yolk sac on growth, liver total lipids and serum total lipids in broiler chicks.

Two experiments were conducted to investigate the effect of the residual yolk sac on growth and total lipids in serum and liver of newly hatched broiler chicks. In each experiments 36 one day old broiler chicks (Lohmann) were allocated to three groups according to the status of the residual yolk sac; deutectomized (surgical ablation of the residual yolk sac, Y), sham operated (S) or intact chicks (I). Y chicks, when compared to S or I chicks, exhibited significant reduction in body weight gain during the 1st week of age. Feed intake was not significantly affected by removal of residual yolk sac. Removal of the residual yolk sac had no effect on serum total lipids and serum cholesterol during 8 days post-hatch and dietary fat absorption for 15 days. Significant interaction between age and removal of residual yolk sac was observed for liver total lipids. Furthermore, the results showed that the liver total lipids, serum total lipids and serum cholesterol were significantly lower at day 8 compared to day 2. The results of this study indicated that removal of the residual yolk sac had no effect on serum total lipids, serum cholesterol, dietary fat absorption and liver weight. However, it reduced the growth of the chicks for the first week of age, after which the chicks compensate for this reduction. The removal of the residual yolk sac showed significant interaction with age for liver total lipids.