Effect of different levels of chromium chloride on performance and antibody titre against Newcastle and Avian Influenza virus in broiler chicks FARSHID KHEIRI 1 * and MAJID TOGHYANI 2 1 Department of Animal Science, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran. 2 Department of Animal Science, Islamic Azad University, Khorasgan Branch, Iran. *Corresponding author: farshid_kheiri@yahoo.com Three hundred one-day-old male broilers (Ross 308) were allocated to five treatments with four replicates in a completely randomized design. Treatments supplemented with 0 (control), 400, 800, 1200 or 1600 ppb chromium in the form of chromium chloride. All birds were intramuscularly immunized with killed vaccine of Newcastle and Avian Influenza (H9 N2) virus at 8 d. On days 18 and 28 blood samples were collected from the wing vein of eight birds per treatment and serum antibody titres against Newcastle and Influenza virus were determined. At 42 days of age, two chicks from each replicate were slaughtered, spleen and bursa of fabricius were removed, weighed and expressed as a percentage of live body weight. Body weight, weight gain and feed efficiency improved significantly (P<0.05) in broilers fed 1600 ppb supplemental chromium. Feed intake of broilers was not affected by supplemental chromium. Percentage of bursa of fabricius and spleen in broilers fed 1600 ppb chromium increased. Broilers fed chromium supplementation had higher antibody titres against Newcastle and Influenza virus (P<0.05). The results of this experiment indicated that chromium supplementation improved performance and antibody titre against Influenza and Newcastle virus in broiler chicks. Key words: broiler; chromium chloride; performance; antibody titre. Introduction Trivalent chromium (Cr) is a well known essential trace element for human and animals (Schwartz and Mertz, 1959). Cr is a component of an oligopeptide low molecular-weight Cr-binding substance, chromodulin, functioning as a part of the insulin signalling auto-amplification mechanism (Vincent, 2000). This element is also involved in carbohydrate, lipid, protein and nucleic acid metabolic function (Steele and Rosebrough, 1981; Ohba et al., 1986; McCarty, 1991). Dietary Cr supplementation has been shown to positively affect growth rate and feed efficiency in growing poultry (Cupo and Donaldson, 1987; Lien et al., 1999; Sahin et al., 2002). Improvements in immune response have been observed when Cr were supplemented to broilers (Luo et al., 1999), stressed feeder calves (Chang and Mowat, 1992; Moonsie-Shageer and Mowat, 1993) and dairy cows (Burton et al., 1993). Nevertheless, recommendations regarding the dietary inclusion level of Cr in diets of livestock including poultry are yet to be finalized (National Research Council, 1994). Moreover, poultry diets are composed mostly of ingredients from plant origin, which are low in Cr (Giri et al., 1990). The present experiment was conducted with broiler chickens receiving either no Cr supplementation or different levels of Cr chloride. The objective of this study was to assess the effects of these supplemental Cr on performance and antibody titre against Newcastle and Avian Influenza virus in broiler chicks. 16th European Symposium on Poultry Nutrition 331