This study was undertaken to investigate the growth performance and immune responses of broiler chicks fed diets supplemented with conjugated linoleic acid (CLA). Two hundred and forty day-old Arbor Acre male broiler chicks were randomly allotted into four dietary treatments with different inclusion levels of CLA (0, 2·5, 5·0 or 10·0g pure CLA/kg) for 6 weeks. Growth performance, lysozyme activity, peripheral blood mononuclear cell (PBMC) proliferation, prostaglandin E2 (PGE2) synthesis and antibody production were investigated. There were no significant differences in growth performance among treatments (P>0·05). Chicks fed 10·0g CLA/kg diet produced 40% and 49% more lysozyme activity in serum and spleen than the control group at 21d of age (P<0·05). Dietary CLA enhanced the PBMC proliferation in response to concanavalin A at the age of 21 and 42d (P<0·05). Systemic and peripheral blood lymphocytic synthesis of PGE2 in chicks fed 10·0g CLA/kg diet was significantly decreased by 57% and 42% compared to chicks fed control diet (P<0·05). Antibody production to sheep red blood cell and bovine serum albumin were elevated in either 2·5 or 10·0g CLA/kg dietary treatments (P<0·05). The results indicated dietary CLA could enhance the immune response in broiler chicks, but did not alter the growth performance.
Metabolizable Energy Value of Conjugated Linoleic Acid for Broiler Chicks and Laying Hens