Effects of conjugated linoleic acid. 2. Embryonic and neonatal growth and circulating lipids

The present study was designed to investigate the effects of conjugated lin oleic acid (CLA) on yolk usage and circulating very low density lipoprotein s (VLDL) during incubation (Day 15) and through 6 d posthatch. Eggs enriche d with CLA were obtained from hens subjected to the following treatments. G roup A hens served as the control group, Group B hens received 1 g CLA ever y other day, Group C hens received 1 g CLA every 4th d, and Group D hens we re sham-supplemented with 1 g safflower oil every other day. Enrichment wit h CLA did not effect fertility, hatch of fertile, BW, or yolk-free BW of em bryos or chicks. However, there were significant changes in relative yolk s ac weight (RYW) and composition of circulating VLDL particles. Across all d ietary treatments (Groups B, C, and D), 15-d embryos had smaller RYW compar ed with Group A embryos; this difference remained through 2 d posthatch. Du ring that period (15 d of incubation through 2 d posthatch), however, embry os and chicks from Group B hens exhibited a unique absorption pattern such that little to no yolk was utilized between hatch and 2 d posthatch, a peri od normally characterized by high yolk-lipid utilization. Similar to the RY W effects, VLDL particles were also altered by hen-induced treatment. Speci fically, at hatch, chicks from Group A hens had the highest percentage of t riglycerides (TG) within their VLDL particles compared with chicks from hen s under all other treatments. This trend in VLDL particles was continued at 4 d posthatch. The present study demonstrates that CLA enrichment of eggs alters relative yolk sac absorption and the composition of circulating VLDL particles.