EFFECTS OF MELATONIN ON PHYSIOLOGICAL RESPONSES OF BROILER CHICKENS TO CONTINUOUS LIGHTING, HEAT AND ROAD TRANSPORTATION STRESSES DURING THE HOT-DRY SEASON

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dc.contributor.authorSINKALU, Victor Olusegun
dc.date.accessioned2014-03-06T08:07:11Z
dc.date.available2014-03-06T08:07:11Z
dc.date.issued2012-11
dc.descriptionA DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA. IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF DOCTOR OF PHILOSOPHY IN VETERINARY PHYSIOLOGY DEPARTMENT OF PHYSIOLOGY, FACULTY OF VETERINARY MEDICINE, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA NOVEMBER, 2012en_US
dc.description.abstractExperiments were performed with the aim of determining the impact of heat and transportation stresses on the behavioural, physiologic responses and performance of broiler chickens, administered with melatonin during the hot-dry season in the Northern Guinea Savannah zone of Nigeria. Broiler chicks were assigned randomly into three groups, comprising 100 chicks each. Group I was raised under natural photoperiod of 12 h light and 12 h darkness, without melatonin supplementation. Group II was kept under 24-h continuous lighting, without melatonin administration. Group III was raised under 24-h continuous lighting, with melatonin supplementation at 0.5 mg/kg per os, via drinking water. Melatonin was administered once daily for 56 consecutive days at 17:00 h from 2nd April to 29th May, 2010. The weekly mean temperature-humidity index recorded inside the poultry house was lowest at week 4 of the study, with the value of 48.60 ± 0.08 oC, but highest at week 1, with the value of 53.48 ± 0.97 oC (P < 0.0001). On day 42, the mean value of body weight of 2420 ± 50 g/bird was obtained in group III birds, while values recorded in groups I and II broilers were 1470 ± 30 g/bird and 1907 ± 38 g/bird, respectively. Dry-bulb temperature was negatively, but significantly (P < 0.01) correlated with feed consumption in groups I (-0.633), II (-0.597) and III (-0.615) broiler chickens. The Giemsa’s, Leishman’s and Wright’s staining methods, successfully used in the laboratory for the first time in the present study, showed broilers’ heterophils, lymphocytes, eosinophils, monocytes and basophils. The least erythrocyte, haematocrit, haemoglobin and mean corpuscular volume, but highest values of red cell distribution width were obtained in group I birds. The highest heterophil:lymphocyte ratio was obtained in group II birds. The significantly (P < 0.05) highest value of mean corpuscular 8 haemoglobin was obtained in group III. The overall mean hourly rectal temperature value of 41.50 ± 0.02 oC, obtained in the group I birds was significantly higher (P < 0.001) than the value of 41.14 ± 0.04 oC recorded in group III, but lower than that of 41.65 ± 0.02 oC obtained in group II birds. The diurnal variation in osmotic fragility of erythrocytes from the birds was highest in group II broilers, followed by those in group I and lowest in the group III broiler chickens. The overall value of 21.83 ± 1.01 % for panting obtained in group III birds was significantly (Kruskal Wallis Test = 17.45; P < 0.0001) lower than the values of 69.72 ± 6.77 % and 67.87 ± 7.19 %, recorded in birds from groups I and II, respectively. The post-transportation malondialdehyde concentration of 2.99 ± 0.20 μmol/ml and 2.57 ± 0.21 μmol/ml recorded in groups II and III, respectively were significantly (P < 0.05) higher than the corresponding pre-transportation values. Aspartate aminotransferase, alanine aminotransferase, creatine kinase and alkaline phosphatase activities rose significantly (P < 0.05) after transportation in all the groups. However, the activities of the endogenous enzymes, with the exception of super oxide dismutase in group III birds, were not significantly (P > 0.05) altered by road transportation. The trend of results obtained demonstrated that melatonin administration to broiler chickens enhanced their growth and productivity. It is concluded that melatonin administration alleviated the deleterious effects of continuous lighting and heat stress on broilers. Its oral administration prior to road transportation may enhance the survival and health status of broiler chickens in the tropical zones of the world.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/3305
dc.language.isoenen_US
dc.subjectEFFECTS OF MELATONINen_US
dc.subjectPHYSIOLOGICAL RESPONSESBROILER CHICKENSen_US
dc.subjectCONTINUOUS LIGHTINGen_US
dc.subjectHEAT AND ROAD TRANSPORTATIONen_US
dc.subjectSTRESSESen_US
dc.subjectHOT-DRY SEASONen_US
dc.titleEFFECTS OF MELATONIN ON PHYSIOLOGICAL RESPONSES OF BROILER CHICKENS TO CONTINUOUS LIGHTING, HEAT AND ROAD TRANSPORTATION STRESSES DURING THE HOT-DRY SEASONen_US
dc.typeThesisen_US
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