We investigated the effects of dietary alpha -linolenic acid (LNA; 18:3n-3) of laying hens on the fatty acid composition of liver microsomes and activity of Delta -6 desaturase in hatched chicks. Laying hens were fed wheat-soybean meal-based diets with (Flax) or without ground flax (control). At Day 21 of feeding, fertile eggs were collected and incubated. On the day of hatching, chicks (n = 6) were killed, and liver microsomes were isolated and assayed for Delta -6 desaturase enzyme activity. The total n-3 fatty acids in the Flax eggs was 13.0% compared with 2.3% (P < 0.001) in the control group. LNA was the major n-3 fatty acid in the Flax eggs and constituted 10%. The long-chain n-3 polyunsaturated fatty acids (PUFA) (20:5n-3, 22:5n-3 and 22:6n-3) constituted 3.1% in Flax eggs compared with 1.5% in control eggs. Docosahexaenoic acid (22:6n-3) composed 2.1 and 1.2% in Flax and control eggs (P < 0.05), respectively. The liver microsomes of Flax chicks incorporated higher 18:3n-3, 20:5n-3, and 22:5n-3 (P < 0.05) with a concomitant reduction in 20:4n-6, 22:4n-6, and 22:5n-6 compared with control chicks (P < 0.05). The Delta -6 desaturase activities in Flax and control groups were 49.4 and 82.8 pmol/min per mg of protein, respectively (P < 0.05). These results demonstrate the role of maternal and yolk n-3 fatty acids in modulating the activity of rate-limiting enzymes for PUFA synthesis in hatched chicks.
