Effects of dietary ratio of linoleic to linolenic acid on performance, antibody production, and in vitro lymphocyte proliferation in two strains of leghorn pullet chicks.

The effects of dietary ratio of linoleic acid to linolenic acid on performance, mitogenic lymphocyte proliferation, and antibody production were evaluated in Leghorn pullets during a rigorous vaccination program. Diets were supplemented with flaxseed and corn oil to achieve 4 dietary ratios of linoleic acid to linolenic acid [17:1 (control), 8:1, 4:1, or 2:1]. Each diet was fed to HyLine Brown or W-36 pullets from 1 d to 16 wk of age. Day-old pullets were randomly assigned to 8 replicate cages with 12 pullets per cage; the density was reduced to 8 pullets per cage at 11 wk of age. Dietary treatments did not affect body weight, feed consumption, or pullet mortality. At 12 wk of age, an interaction between diet and strain (P < or = 0.004) showed Hy-Line W-36 pullets fed the 2:1 ratio had greater antibody production against Newcastle disease virus (NDV) vaccine than those fed diets with higher ratios. At wk 16, pullets fed ratios of 4:1 and 2:1 had the greatest antibody production against NDV vaccine. Antibody production against infectious bursal disease virus (IBDV) vaccine was also increased (P < 0.04) by ratios of 4:1 (2.244 optical density; OD) or 2:1 (2.508 OD) as compared with the control diet (1.576 OD). Hy-Line Brown pullets had greater antibody production against infectious bronchitis virus vaccine compared with Hy-Line W-36 pullets at 16 wk of age. These results indicate that feeding a reduced dietary ratio of linoleic to linolenic acid by adding flaxseed to the diets enhanced antibody response to NDV and IBDV vaccines without any negative effects on pullet performance.