| Titles |
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English :
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Thermoregulatory mechanisms of sheep and goats to water deprivation under hot climate
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Arabic :
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ميكانيكية التنظيم الحرارى فى الاغنام و الماعز المعطشة تحت ظروف الطقس الحار
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| Abstract |
The experiment was carried out at Sakha Experimental Station, Animal Production Research Institute, Ministry of Agriculture, located at the Kafr El-Sheikh Governorate (Latitude 31 North, Longitude 31 East). Ten % Finnish Landrace x Rahmani ewes and ten % Damascus x Baladi goats were randomly assigned to two equal groups Le. control and water deprived groups. Animals were fed on hay and concentrates according to their body weight requirements according to NRC (1985) for sheep and NRC (1981) for goats. Feed was provided once daily (after being withheld for 12 hours before taking measurements), accompanied by drinking water for the control group.
2.1. EXPERIMENTAL DESIGN
Animals were weighed immediately before taking measurements and at the end of the experiment (after 4 days). Ambient temperature (AT), and relative humidity (RH%) were measured throughout the experimental period. Measurements and blood samples were taken individually before water deprivation (zero time, 12 hours without food or water) then after 4 days from the zero time.
2.1.1. Thermoregulatory Parameters
Rectal temperature (RT, DC) was measured using a clinical thermometer. Skin temperature (ST, DC) and ear temperature (ET, DC) were measured using a portable infrared thermometer designed for temperature measurements in the range of -50 to 500°C (Minolta/Land Cyclops Com pac 3.).
Respiration rate (RR) was measured by counting the flank movements in one minute. Respiratory minute ventilation (gas volume as 1/minute STPD, MV) was measured by Dry Gas Meter. Tidal volume was calculated by dividing MV/RR. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured using the open-circuit technique according to Yousef and Dill (1969). Oxygen consumption was measured using Oxygen Analyzer (Servomex 570) and CO2 production by Infrared Gas Analyzer (Model-AR-411). Heat production (HP) (measured as fasting metabolic rate, kj/BW.75 per day) was calculated using the equation of Brouwer (1965).
2.1.2. Blood Collection and Analyses of Blood and Plasma
Blood samples were collected from the jugular vein on heparinized tubes and hematocrit value (Ht, %) were measured according to Bauer (1970). Samples were centrifuged at 3000 rpm for 15 minutes and plasma was collected and stored at -20°C until hormonal assay.
Plasma total protein (TP) and plasma albumin (AI) were measured using the kits of Egyptian American Co. from which plasma globulin (GL) was calculated by subtraction and albumin/globulin ratio (AIG) by calculation. Creatinine concentration was measured by a colorimetric method using creatinine kits (Harper and Row, 1974). Direct radioimmunoassay (RIA) technique was performed for the determination of plasma hormones (Triiodothyronine T3, Thyroxine, T4 and Aldosterone). Plasma Na+ and K+ concentrations were determined using the Enzymatic color kits for sodium and potassium.
2.2. STATISTICAL ANALYSIS
The statistical analysis of data was carried out using SAS program (SAS, 1988). Paired T test (proc MEANS of SAS) was run to test the significance between before and after water deprivation.
4. CONCLUSION
It could be concluded that water deprivation for 4 days caused hemoconcentration in sheep and goats without significant effect on their heat balance. However, crossbred goats can tolerant water deprivation better than crossbred sheep and the main thermoregulatory mechanisms fto cope with water deprivation are the decrease in respiratory evaporation, metabolic rate and conservation of body water and plasma volume by increasing plasma osmotic pressure through the increase in plasma aldosterone and Na + concentrations and plasma colloid osmotic pressure by increasing plasma albumin/globulin ration.
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| Publication year |
2008
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| Pages |
70-74
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| Availability location |
معهد بحوث الانتاج ا لحيوانى - شارع نادى الصيد- الدقى- الجيزة
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| Availability number |
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| Organization Name |
Animal Production Research Institute (APRI)
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| City |
طوكيو
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| serial title |
18th International Congress of Biometeorology .
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| Author(s) from ARC |
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| External authors (outside ARC) |
هشام حسين خليفة
جامعة الازهر
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| Agris Categories |
Animal physiology - Nutrition
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AGROVOC
TERMS |
Blood.
Blood composition.
Body temperature.
Goats.
Haematocrit.
Relative humidity.
Respiration rate.
Sheep.
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| Proposed Agrovoc |
Ambient temperature;ear temperature;Heat production;Plasma total protein;plasma albumin;
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| Publication Type |
Conference/Workshop
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