International Journal of Poultry Science 8 (3): 247-251, 2009 ISSN 1682-8356 © Asian Network for Scientific Information, 2009 247 Diurnal Fluctuation in Haematological Parameters of the Domestic Fowl in the Hot Humid Tropics O.I. Azeez, A.A. Oyagbemi and J.O. Oyewale Department of Veterinary Physiology, Biochemistry and Pharmacology, University of Ibadan, Ibadan, Nigeria Abstract: Diurnal fluctuation in haematological parameters such as packed cell volume (PCV), red blood cell (RBC) count, haemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and erythrocyte osmotic fragility of the domestic fowl in the hot humid tropics was investigated using Nera Black cocks. Blood samples were collected from the birds at 6:00 am, 10:00 am, 2:00 pm, 6:00 pm, 10:00 pm and 2:00 am during a 12-hour light and a 12-hour dark period. PCV showed considerable diurnal variation with the lowest value obtained at 10:00 am and the peak value recorded during the early morning (2:00 am). RBC, Hb, MCH and MCHC values also varied according to the time of the day, with the lowest values observed at 2:00 pm, probably as a result of haemodilution following increased feed and water consumption at this period of the day. Peak values for RBC, Hb, MCH and MCHC were observed at 10:00 pm when the birds were already roosting (during the dark phase of the day) as a result of which physical and metabolic activities were generally lowered. Haemoconcentration so produced might be responsible for the higher haematological parameters during the night because the birds were neither eating nor drinking water at this period of the day. Erythrocyte osmotic fragility at 0.3% NaCl concentration was also significantly higher (P < 0.05) at 6:00 am than at any other period of the day. Key words: Diurnal fluctuation, haematological parameters, domestic fowl INTRODUCTION Haematological parameters in birds have been shown to be influenced by various factors such as age, sex, season and nutrition. Packed cell volume (PCV), haemoglobin (Hb) concentration and red blood cell (RBC) count have been reported to increase with age in chickens (Islam et al., 2004), pigeons (Columba livia forma domestica) (Pavlak et al., 2005), turkeys (Oyewale MATERIALS AND METHODS and Ajibade, 1990) and budgerigars (Melopsittacus Twenty-one week old male domestic fowls of the Nera undulatus) (Harper and Lowe, 1998). PCV and Hb black strain were used. The birds belong to a values have also been reported to be higher in males commercial layer strain bred specifically for egg and than in females in turkeys (Oyewale and Ajibade, 1990) meat production in Nigeria. Blood samples were and pigeons (Pavlak et al., 2005). Similarly, seasonal collected from the birds into heparinized tubes at 4 fluctuations in PCV and Hb concentration have been hourly intervals (i.e. 6:00 am, 10:00 am, 2:00 pm, 6:00 reported in pigeons in the tropics (Oladele et al., 2001) pm, 10:00 pm and 2:00 am) during a 12-hour light and and in the cold temperate region (Pavlak et al., 2005). a 12-hour dark period. The samples were taken from the Variations in haematological parameters have also jugular vein of each of 6 groups of birds consisting of 5 been reported in animals of the same age and sex, birds per group at each of the periods. reared under the same conditions when sampled at The red blood cell (RBC) count was determined by the different times of the day (Durotoye et al., 2000; Sanni et haemocytometer method, the packed cell volume (PCV) al., 2000). This significant, but often neglected cause of by the microhaematocrit method and the haemoglobin variations in haematological parameters is as a result of (Hb) concentration by the cyanmethaemoglobin method. diurnal fluctuation or variation in these parameters The mean corpuscular volume (MCV), mean corpuscular following changes in daily physical and metabolic haemoglobin (MCH) and mean corpuscular activities (Sanni et al., 2000; Piccione et al., 2001, 2005). haemoglobin concentration (MCHC) were calculated Thus, according to Ferrer (1990), the time at which blood from the values obtained for RBC, PCV and Hb samples are collected must be considered before according to Jain (1986). conclusions are drawn from the haematological data Erythrocyte osmotic fragility was determined according obtained to ascertain physiological conditions or otherwise in man and animals. This present study was aimed at determining the fluctuations, if any, in the haematological parameters of the domestic fowl in the hot humid tropics over a twenty four-hour period.