The Effect of Different Levels of Valine in Low Protein Diets on Immune System of Broiler Chickens

This experiment was performed to evaluate the effect of different levels of valine in low protein diets on the immune response of broilers. This study was conducted using 200 one-day old male broilers (Ross 308 strain) in a completely randomized design with 5 replications and 10 birds per replication from the age of 8-21 days. Experimental treatments included the control diet, recommended levels of valine (1.359), 10% higher than the recommended level of valine, 20% higher than the recommended level of valine in a diet containing 2% protein diluted. The results show that different levels of valine had no effect on liver, spleen and bursa of Fabricius weight (p < 0.05). Moreover, blood lymphocytes, heterophils, lymphocyte to heterophil ratio, monocytes, basophils and eosinophils did not affected by valine (p < 0.05). Diets containing 20% valine increased the HI antibody and humoral immunity responses (p < 0.05). Inclusion of 10% valine increased the IgM as compared to the other levels (p < 0.05). The secondary response of total antibody was affected by experimental treatments, so that the level of 20% valine increased the total secondary response and IgM secondary response to SRBC (p < 0.05). Moreover the addition of valine had a significant effect on the injection reaction of PHA-P (p < 0.05), and level of 20% valine, increased the cellular immunity of broiler in compared to the control treatment and lower valine levels. The addition of high levels of the valine in low-protein diets improved the cellular and humoral immune systems of broiler chickens.