Effects of Conjugated Linoleic Acid (CLA) Supplementation on Improving Immune Response to Newcastle Disease Vaccination in Broiler Chickens

The aims of this study were to examine the effects of conjugated linoleic acid (CLA) supplementation on improving immune response to Newcastle disease vaccination in broiler chickens. Growth rate and feed efficiency, mortality rate, immunoglobulin levels, and development of lymphoid organs responding to Newcastle disease vaccination were determined and compared to the effects of sunflower oil supplementation. Thee hundred and ninety six, 3-day-old Arbor Acres broiler chickens were equally divided into 4 groups, each with three replications of 33. The first or control group was fed a diet without any supplementation. The second group and the third group were fed diets with 0.5% and 1.0% CLA supplementation, respectively. The forth group was fed a diet with 2.0% sunflower oil supplementation. The experiment was conducted until the chicks reached 64 days of age. The chicks were given Newcastle disease vaccination via nasal route on day 30 and 50. The chickens were weighed every week throughout the experiment. Blood samples were collected on day 30, 37, 44, 57 and 64, respectively. The blood samples were then measured for immunoglobulin (Ig) G levels using ELISA method. On the last day of the experiments, the chickens were put to sleep and lymphoid organs were collected and weighed. The results showed that CLA supplementation at any level had no effect on growth rate, feed efficiency, and mortality rate. One week after vaccination, CLA supplementation caused a higher increase in IgG titer levels and numbers of immunized chickens than those of control group. However, later on, CLA supplementation did not make any difference on IgG levels responding to Newcastle disease vaccination. In addition, it was found that CLA supplementation had no effect on lymphoid organ weight. The effect of sunflower oil supplementation was the same as that of CLA.