Abstract: This experiment was conducted to investigate the effects of dietary grape procyanidins on growth performance and immune function in broiler chickens. Two hundred and forty day-old Arbor Acre male broiler chickens were randomly allotted into four dietary treatments with different inclusion ( 0,7.5,15 or 22.5 mg/kg) of grape procyanidins. The experiment period lasted for 6 weeks. The results showed that chicks fed higher dose of grape procyanidins intake more feed and grew faster during the first 3 weeks. During the second 3 weeks and the whole 6 weeks,chicks fed 7.5 mg/kg grape procyanidins had higher body weight gain and superior feed efficiency,and chicks fed 15 mg/kg grape procyanidins diet had inferior growth performance compared to the controls. Dietary grape procyanidins did not affect the growth of the immune organs. The percentages of CD3⁺,CD4⁺,CD8⁺,αβ and γδ T lymphocytes in peripheral blood had the increased tendency in chicks fed 7.5 mg/kg grape procyanidins. Overall,optimal dose of grape procyanidins in the diet would stimulate late growth and modulate immune function in broiler chickens.

Key words: grape procyanidins; broiler; growth performance; immune function