Using some salts to alleviate heat stress and improve physiological responses in sheep under hot conditions in Egypt

Abstract: This study was carried out in Minia Governorate, Mallawi Experimental Station, Animal Production Research Institute (APRI), Agriculture Research Center (ARC), Ministry of Agriculture in cooperation with Animal Production Department, Faculty of Agriculture, Minia University during the period from June to August 2006.
This study was carried out by using 90 animals (75 Farafra mature ewes aged 2.5 to 4 years old, averaged 39.69 kg of body weight and 15 Farafra mature rams aged 2 to 3.5 years old, averaged 59.27 kg of body weight). The aim of this study was to investigate the effect of using some salts to alleviate heat stress and improve physiological responses in sheep under hot environmental conditions in Egypt.
The experimental animals (rams and ewes) were equally divided randomly to five treatment groups according to their age and initial body weight as follow: control, 1 % Sodium bicarbonate (G,), 1 % Potassium carbonate (G2), 0.5% Sodium bicarbonate + 0.5% Potassium carbonate (G3) and 1 % Sodium bicarbonate + 1% Potassium carbonate (G4). These diet. contains varying levels of DCAD (Na + K - Cl) mEq/kg of DM (115, 246, 276, 257 and 407 for control, G1, G2, G3 and G4, respectively). All animals were subjected to the routine vaccination programs for infectious diseases (foot and mouth disease, rift valley fever, etc.). There are five concentrate mixtures with salts used in this experiment .The concentrate mixtures contained 14% crude protein and 50% starch value. At 8.00 am animals were fed wheat straw in addition to a concentrate mixture.
Climatic conditions:
Ambient temperature (AT) and relative humidity (RH) were recorded simultaneously during the experimental period at morning (6-8 a.m) and afternoon (12-2) p.m.
Physiological parameters:
1. Blood hematocrit and hemoglobin concentration.
Blood samples (10 ml) were collected every 10 days from each animal via Jugular vein using glass tubes. Each blood sample was divided into two parts (heparinized and non - heparinized). Hemoglobin concentration (Hb, g/l) was measured by colorimetric methods. Hematocrit value (Ht) was measured in hematocrit capillary tubes using a hematocrit centrifuge.
2. Serum analysis.
Unheparinized blood samples were centrifuged at 3000 r.p.m for 15 minutes. Serum total protein (TP), urea and glucose concentrations were determined by an enzymatic calorimetric method.
Serum Na and K concentrations were determined using enzymatic measuring. Chloride was determined using Thiocyanate method. Direct radioimmunoassay (RIA) technique was performed for determination of serum hormones . triiodothyronine, thyroxine and testosterone.
3. Thermal responses.
Rectal temperature (RT, °C) was measured using a clinical thermometer. Skin temperature CST, °C) and ear temperature (ET, °C) were measured using infrared thermometer (Radioshack).
4. Respiratory activities and gas exchange.
Respiration rate (RR) was measured by. counting the flank movements in one minute. Respiratory minute volume of exhaled air/minute was measured by Dry Gas Meters (liters) and gas volume was corrected to Standard Dry Temperature and Pressure (STPD). Volume of oxygen consumption (Vo2), carbon dioxide production (VCo2) and respiratory quotient (RQ%) were measured with the open-circuit technique.
5- Reproductive performance :
5.1 Rams.
Semen physical characteristics of rams were evaluated, Ram were examined and trained for semen collection two months before the experiment. Semen samples were collected using artificial vagina once each 10 days. Immediately after, ejaculation, semen samples were placed in water bath at 37°C. Semen was evaluated in term of (pH, volume, motility, sperm concentration, live, dead sperm and abnormal spermatozoa counts).
5.2 Ewes.
Conception rate and embryonic mortality during the mating season were determined by using sonar. Two examinations were taken. The first was after 40 days post mating and the second was after 85 days post mating.
The results can be summarized as follows:
1. Dietary electrolytes increased insignificantly blood Hb and significantly decreased (P<0.05) blood Ht in both rams and ewes.
2. The values of glucose, total protein, Na and K tended to significantly increase (P<0.05), DEB values were significantly increased (P<0.0l), serum urea values were increased insignificantly and serum CI tended to significantly decrease (P<0.05) in both rams and ewes by dietary salts.
3. Dietary salts insignificantly increased serum triiodothironine and thyroxine of rams and ewes and significantly increased (P<0.05) serum testosterone of rams.
4. Dietary electrolytes significantly increased (P<0.05) semen pH, ejaculate volume, sperm motility, live sperm percentage, sperm concentration per ml, while significantly increased (p<0.01) sperm concentration per ejaculate and significantly decreased (P<0.01) abnormal sperm percentage.

5. Sonar results indicated that dietary salts had a beneficial effect on conception rate and decreasing embryo mortality specially, in the third treatment group (G 3).
6. Treated rams and ewes had a significant (P < 0.01) decrease in the value of rectal temperature, skin temperature at morning (6-8 a.m) and afternoon (12-2p.m) and significant (p<0.01) decrease in respiration rate.
7. Dietary salts insignificantly decreased ear temperature of ewes at morning. While, significantly decreased (p< 0.05) ear temperature in rams. And at afternoon ear temperature significantly decreased (p<0.05) of both rams and ewes.
8. Gas volume and tidal volume significantly increased (p<0.05) by dietary salts in both rams and ewes.
9. Dietary salts significantly increased (p<0.05) VO2 of rams and ewes. While, at the same time insignificantly decreased VCO2 in both rams and ewes. Also, dietary salts decreased significantly (p<0.01) RQ.
Publication year 2008
Pages pp.145
Availability location مكتبة معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى- الجيزة
Availability number 1053
Organization Name
Country Egypt
Author(s) from ARC
Agris Categories Animal physiology - NutritionAnimal physiology - Reproduction
Egypt. Heat stress. Rams. Reproductive performance. Salts. Sheep. Sodium bicarbonate. Warm season.
Proposed Agrovoc physiological responses;hot conditions;potassium carbonate;
Publication Type Master Thesis