| When exposed to a hot and damp environment, animals are susceptible to heat stress. The sweat glands of pigs are under development, when heat stress happens, pigs radiate heat through starting perpheral blood circulation, stengthening lung’srespiration and kidney exretion.When the animal can not radiate heat well under heat stress, further changes in the blood and other organs will be happened. Furthermore, heat stress results in the tissue injuries, impacts on the absorption of nutrition and leads to a decrease in growth and production performance. Some studies have shown that the extracted complex, prepared mainly from gypsum, wrinkled giant hyssop, cortex phellodendron, etc., is able to promote the heat radiation and remove the rheumatism. In the present study, the simulated high-temperature environment were used to study the effects of four kinds of gypsum and complex preparation on heat dissipation in heat-stress pigs, aim to provide the basis for envionment control and nutritional hygiene manipulation techniques.The current study includes the following five experimental parts.1、Variations of physical and biochemical index and effects of complex preparation in heat-stress pigletsChinese experimental piglets (CEMP) were housed in the artificial climate climber with simulating high-stress environment for 10 days (40℃,5h/d). Variation of physiological and biochemical index affected by complex preparation were used to study the effects of heat stess on production performance and serum biochemical targets in pigs. In this paper,48 2-month piglets were randomly divided into three groups:normal temperature group (NTG), heat treatment group (HTG), Chinese herbal medicine extract compound agents group (CHG) under heat stress. On day 1,3,6 and 10, we randomly selected 4 pigs from each group, then weighed and collected the fresh blood from the vein, and separated serum and measured the blood levels of heat-stress protein 70. The result showed that temperature of the HTG was higher and appeared the symptoms of pant, dysentery, tiredness and losing appetite, etc. Furthermore comparing with the HTG, the daily feed intake and the weight gain heighten(P<0.05) and the serum cortisol and heat-stress protein 70 decreased (P<0.05). The complex preparation could improve growth performance of heat-stress piglets significantly.2、Characteristics of skin microcirculation and effects of complex preparation in heat-stress pigletsThis part reported the effects of complex preparation on blood cells concentration and NO and ET-1 contents of the blood vessel. On day 1,3,6 and 10, we randomly selected 4 pigs from each group, and used Laser Doppler Flowmetry to determine the surface capillary blood flow of pigs. Ten ml fresh blood was collected from the front cavity vein of each pig and the changes of NO and ET-1 contents were determined. The result showed that the blood cell concentration of the HTG was higher than that of the NTG on d 1,3,6, and 10(P<0.05); the NO content of the HTG gradually dropped, and was significantly lower than that of the NTG on d 10(P<0.05). In the ETG, the blood cells concentration decreased and NO content increased significantly on d 10(P<0.05), but no significantly influence on the ET-1 content was observed (P>0.05). The result showed that heat stress caused an increase in the blood cells concentration, a decrease in the speed of blood flow on the day of 10, an imbalance in the NO and ET-1 contents and the blood condensation, thus influencing the heat dissipation. The complex preparation could regulate the blood cells concentration, thus improving the rate of heat dissipation in piglets exposed to high-ambient temperature.3、Variations of whole blood viscosity and red blood cell (RBC) deformation index and effects of complex preparation in heat-stress pigletsThis part studied the effects of complex preparation on whole blood viscosity (WBV), RBC deformation and hematocrit (HCT). On day 1,3,6, and 10, we randomly selected 4 pigs from each group, collected 10 mL fresh blood from the front cavity vein of each pig, and analyzed the hemorheological parameters. Five mL fresh blood sample of each pig was put into plastic test tubes containing sodium heparin(0.2 mg/mL), of which 1.0 mL of blood was used for testing the packed cell volume(PCV) by the Wintrobe method; the rest of the blood was used to determine the whole blood viscosity(WBV) at the shear rates of 200 s-1 and 1 s-1, and other hemorheological parameters. The result showed that compared with the NTG, the WBV shear rate value of the HTG was significantly higher on d 10(P<0.05), the RBC deformation index was significantly lower on d 6 and 10, and the HCT was significantly higher on d 6 and 10. After the administration of the Chinese herbal medicine extract complex preparation, the RBC deformation index of the therapy groups showed substantial restoration to their normal state, especially on d 10 (P<0.05). This showed that continuous heat stress can increase the blood viscosity to reduce the amount of blood perfusion and RBC fatigue affect nutient supply capicity. Further, the Chinese herbal medicine extract complex preparation can alleviate the heat-stress induced pathological injuries.4、Damages of lung and kidney tissues and effects of complex preparation in heat-stress pigletsThis part studied the recovery of complex preparation on lung and kidney tissues injuries, and performed pathological analysis on the lungs and kidneys. On d 1,3,6, and 10, 4 pigs in each experimental group were killed, and their lung and kidney tissues were extracted. First, the lung and kidney tissues were fixed in 4%neutral formalin; thereafter, these tissues were finally embedded in paraffin wax, cut into 5μm successive sections, stained with hematoxylin-eosin(H-E) dye, and observed under the microscope. After performing the pathological analysis, heat stress caused various injuries to lung and kidney tissues in piglets. The result showed the persistent heat stress resulted in the heavy load to circulation system, and influenced the blood supply to heat-exchange surfaces, leading to cell tissues to lack of oxygen and blood, the imbalance of nutrition, tissues injuries and a series of serious metabolic disorder. The Chinese herbal medicine extract complex preparation can alleviate the heat-stress induced pathological injuries of lungs and kidneys.5、Variation of the contents of AVP and cAMP in hypothalamus and effects of complex preparation in heat-stress pigletsThis part studied the effects of complex preparation on AVP and cAMP contents inhypothalamus, analyzed the function of regulating the temperature through the dynamic changes of the contents of AVP and cAMP, and explored the mechanism that the anti-heat-stress of Chinese herbal medicine. On day 1,3,6, and 10, four pigs in each experimental group were selected and determined the changes of the temperature by digital thermometer. These pigs were anaesthetized and then killed, and rapidly extracted the brains from their heads. Taking tuber cinereum and optic chiasma as the center, determined the place of hypothalamus and extracted them, and determined the contents of AVP and cAMP. The result showed the temperature of the HTG went up, and the content of AVP was significantly lower on d 3,6 and 10(P<0.05); the content of AVP of the ETG was significantly higher than that of the HTG(P<0.05). The content of cAMP of the HTG was significantly higher on d 10 (P<0.05), while the content of cAMP of the ETG was significantly lower than that of the HTG on d 10 (P<0.05).The results showed that continuous high temprature can improve the concentration of cAMP and maintain a high body temprature to lose heat. The complex preparation can alleviated the effects. |
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