Dietary L‐arginine modulates immunosuppression in broilers inoculated with an intermediate strain of infectious bursa disease virus

BACKGROUND The effects of dietary l ‐arginine (Arg) on immunosuppression following infectious bursal disease virus ( IBDV ) inoculation in broiler chickens were evaluated. The design of this study was a 5 × 2 factorial arrangement ( n = 5) with five Arg concentrations (starter: 9.9, 13.9, 17.6, 21.3 and 25.3 g kg −1 ; grower–finisher: 9.5, 13.5, 17.1, 20.1 and 23.6 g kg −1 ) with or without IBDV inoculation ( IBDV or saline inoculation at 14 days). Chickens were sampled at 2, 4 and 6 days post‐inoculation ( DPI ) and 42 days of age. RESULTS The IBDV inoculation decreased ( P = 0.05) CD3 + , CD4 + , and CD8 + T cell counts at 2 days post‐inoculation ( DPI ) and monocyte counts at 6 DPI ; and reduced ( P < 0.05) bursal interleukin‐1β ( IL ‐1β) mRNA expression at 2 DPI and serum IL ‐6 concentration at 4 DPI . Increasing Arg concentration increased ( P < 0.05) CD4 + and CD8 + T cell counts at 2 DPI , linearly increased ( P = 0.05) CD3 + T cell counts in IBDV ‐inoculated groups and monocyte counts in control groups at 4 DPI ; increased ( P < 0.05) serum IL ‐6 concentration in IBDV ‐inoculated groups at 2 DPI ; and increased ( P < 0.05) serum anti‐ IBDV antibody titres at 42 days of age. CONCLUSION Varying concentrations of Arg supplementation attenuated IBDV inoculation induced immunosuppression via modulating circulating T cell sub‐populations. © 2014 Society of Chemical Industry