International Journal of Poultry Science 4 (8): 573-579, 2005 ISSN 1682-8356 © Asian Network for Scientific Information, 2005 573 Comparative Studies on Haematological Values of Broiler Strains (Ross, Cobb, Arbor-acres and Arian) A. Talebi*, S. Asri-Rezaei, R. Rozeh-Chai and R. Sahraei Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, P.O. Box 1177, Urmia, Iran E-mail: a.talebi@mail.urmia.ac.ir Abstract: Measurement of haematological parameters provides valuable information for evaluation of health status of man and animals, but due to lack of reference values for avian blood profiles, it is not widely used in poultry. This study has contributed to the current knowledge on avian blood profiles, or more specifically demonstrated leukograms and haemograms of four main broiler strains (Ross, Cobb, Arbor-Acres, and Arian) during 8 weeks husbandry period. Blood samples were collected from chickens at different age (1 to 56 days old) with 7-day sampling intervals. Total numbers of RBC and WBC, PCV, Hb, MCV, MCH, MCHC, ESR, together with absolute count of heterophils, lymphocytes, monocytes, eosinophils, and basophils as well as H / L ratio were determined. One-way ANOVA, Wilcoxon, Spearman correlation and Kruskal-Wallis H tests from SPSS11 were used for statistical analysis of the results. This study showed that age affects significantly (P<0.05) the haematological profiles of the broiler strains. With increasing of age, the erythrocytic parameters (except MCV, MCH, and MCHC) and leukocytic parameters (except heterophils and H / L ratio) were significantly increased (P<0.01), but MCV, MCH and absolute count of heterophils as well as H / L ratio were significantly decreased (P<0.01). Key words: Haematology, leukogram, haemogram, ross, cobb, arian, arbor-Acres, broiler strains Introduction Poultry industry continuously advancing by improvement of genetic potential of new broiler strains (Kemp and Kenny, 2003) to provide the high-quality with low-cost protein requirements of the human population world- wide. Genetic development for rapid growth together with intensive husbandry conditions have expedite the outbreaks of avian diseases. To combat clinical and subclinical forms of poultry diseases, accurate and differential diagnosis of the diseases at early stages of infections is necessary. Measurement of haematological parameters provides valuable information in this regards and routinely used in human’s and animal’s medicines, but unfortunately due to lack of information, blood profile have not been widely used in avian medicine (Mushi et al., 1999; Kral and Suchy, 2000). Avian blood differs in cells’ characteristics from their mammalian counterpart (Smith et al., 2000). Several factors including physiological (Alodan and Mashaly, 1999) and environmental conditions (Vecerek et al., 2002, Graczyk et al., 2003), diet contents (Odunsi et al., 1999; Kurtoglu et al., 2005), water and feed restriction (Galip, 1999; Al-Rawashdeh, et al., 2000; Iheukwumere and Herbert, 2003), fasting (Lamosova et al., 2004), age (Furlan et al., 1999; Naziefy-Habibabadi, 1997; Seiser et al., 2000), administration of drugs (Khan, et al., 1994; Zaman et al., 1995), anti-aflatoxin premixes (Oguz et al., 2000) and continuous supplementations of vitamin E (Tras et al., 2000) affect the blood profiles of healthy birds. Although there is limited information concerning the normal blood profiles of different broiler strains at different ages. However, some haematological studies in birds have been carried out by a number of authors (Levi et al., 1989; Uko and Ataja, 1996b; Onifade and Odunsi, 1998; Hauptmanova et al., 2002) and a few haematological parameters of some broiler strains (Lohmann, Hubbard and Arbor-Acres) at very limited age of husbandry period have been studied (Qaisar et al., 1996). Reference blood profiles of broiler strains in natural condition on different age of husbandry period are essential for interpretation of haematological tests (Mushi et al., 1999; Seiser et al., 2000). Therefore, this study was carried out: a) To determine haematological values including total red blood cells (RBC) and white blood cells (WBC) count, pocked cell volume (PCV), haemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), erythrocyte sedimentation rate (ESR) and differential leukocyte count of the broiler strains during 8 weeks husbandry period. b) To compare blood profiles of these genetically improved broiler strains with each other. This study differs from previous studies in some aspects; a) covers whole breeding period as well as after hatch, b) includes nearly all parameters of