Effects of immunomodulatory nutrients on growth performance and immune-related gene expression in layer chicks challenged with lipopolysaccharide

Immunomodulatory nutrients alter the immune response to pathogens. This study was conducted to determine the effects of immunomodulatory nutrients on the immune response to a lipopolysaccharide (LPS) challenge of layer chicks fed supplemental corn oil (control; 3%), fish oil (3%), conjugated linoleic acid (CLA; 1%), lutein (0.05 g/kg), or vitamin E (90 I. U./kg). Four-week-old layer chicks were allotted to 10 treatment groups arranged as a 2 x 5 factorial with 2 sexes and 5 dietary treatments (TRT; 5 replicate pens of 2 male and 2 female chicks per TRT). After a 2-week diet adaptation, all birds were injected intraperitoneal with 1.5 mg/kg BW LPS. Twelve hours post challenge, samples were collected. Fish oil fed birds had greater (P = 0.03) spleen weight (% final BW) than the CLA fed birds. In the liver, the fish oil TRT had higher (P = 0.040) IL-12 expression than the corn oil TRT, but the corn oil TRT had greater (P = 0.001) IL-4 expression than the CLA, lutein, and vitamin E TRT. There was a main effect of sex of the birds on growth parameters at 12 h post LPS challenge in which male birds had greater beginning BW (P < 0.001), final BW (P < 0.001), and greater 12-hour BW loss (P = 0.020) than the female birds, but not relative weight loss. There were also main effects of sex on immunerelated gene expression with the females having greater gene expression than the males in the duodenal mucosal scrapings [IL-1 beta, IL-12, and TLR-4 gene expression (P = 0.026, 0.011, and 0.002, respectively)]; liver [IL-10, IL-4, and iNOS gene expression (P = 0.017, 0.032, and 0.006, respectively)]; and spleen [IL-1a, IL-10, IL-4, and iNOS gene expression (P = 0.001, 0.001, 0.001, and 0.005, respectively)]. Therefore, each immunomodulatory nutrient added to the diets of layer chickens resulted in different immune responses to an LPS challenge.