Seasonal Variation of Physiological and Biochemical Indexes of White-tibetan Sheep

Mingliang ZHOU,Minghua CHEN,Weisheng WU,Rongqing XIE,Shihai JIANG,Pinggui YANG

Sichuan Academy of Grassland Science,Chengdu 611743,China

Responsible editor:Nanling WANG Responsible proofreader:Xiaoyan WU

White Suffolk sheep was a breed of meat sheep and set about developing with white head and black limb in Australia from 1977[1],which was crossed from Suf folk sheep and Borderleicester sheep,and Suffolk sheep and Polled Dosert sheep,then the black individuals of generation F2were eliminated and the individuals with higher production property were chosen for breeding gradually.In recent years,white Suffolk sheep have been introduced into North China,moreover,the hybridization between white Suffolk sheep and Chinese Merino sheep (Xinjiang)[2],Small Tail Han sheep[3],Gansu alpine fine-wool sheep[4]etc.was widely carried out,and the filial generation was improved significantly in birth weight,weaning weight,six-month-age weight and yearling weight etc.The hybrid vigor of the hybridization of white Suffolk sheep with local sheep was growth speed at the early stage,therefore,white Suffolk sheep can be used as the terminal male for highquality lamb production.

In 2009,Sichuan Academy of Grassland Science introduced 12 white Suffolk sheep from Australia(3♂,9 ♀),and the sheep were fed in the Base of Xinjin County in Chengdu City for two years,which belongs to Sichuan Academy of Grassland Science,at the same time,the rams were transported to Tibetan Sheep Breeding Center of Sichuan in Hongyuan County for crossing with local Tibetan sheep,their generation was called“White-Tibetan sheep”; after several years’arduous efforts,a group of hybrid F1of White-Tibetan sheep was got.

It is an urgent need to solve the problem whether the White-Tibetan sheep are adapted to the climatic environment of high and cold,hypoxia and high altitude area.Therefore,the physiological indexes of White -Tibetan sheep,and the physiological and biochemical indexes of blood were measured to reserve normal physiological values of White-Tibetan sheep and physiological and biochemical normal value of blood,so as to lay a foundation for studies of disease surveillance and environmental adaptation,as well as subsequent studies of White-Tibetan sheep.

Hongyuan County of Sichuan Province is located in 31°51′-33°19′N and 101°51′-103°23′ E,the average elevation of the whole county is 3 600 m,belongs to cool temperature monsoom climate of continental plateau,its major characteristics are:cold,the four seasons can hardly be divided obviously,spring and autumn are short,while winter is very long,moreover,it hasn’t summer,the heat is low; there is a clear distinction between the dry season and the rainy season,however,the rain and the heat are occurred in the same season; the sunlight time is long,and the solar radiation is strong; disastrous weather is frequent;January is a cold month,and the average temperature is-10.3 ℃,the hottest month is in July,and its average temperature is 10.9 ℃;the extremely minimum temperature is -36 ℃,and the the extremely maximum temperature is 25.6 ℃; the annual average sunshine is 2 417 h,the annual average rainfall is 753 mm and 80% of it is during May-October,the annual average snow cover period is 76 d,and somethimes it is as long as three months,sometimes it is as short as about two months.The natural grassland area of Hongyuan County is 77.2 ×104hm2,which accounts for 91.8% of total grassland area,the available high-quality grassland area reaches 74.7×104hm2,which provides high-quality composite feed resources for yak and sheep,etc.

Materials and Methods

Experimental population

White Suffolk sheep,after the transitional feeding in Xinjin area of Chengdu City,were transported to Hongyuan County for feeding in the summer of 2011,at the same time,the hybridization and improvement of white Suffolk sheep and Tibetan sheep was carried out.The experiment takes White-Tibetan sheep as the research object,and measures the physiological indexes of White-Tibetan sheep with 1-2 years old,and the physiological and biochemical indexes of blood according to the four seasons.

Blood specimen collection

2 ml blood sampling was collected from sheep with an empty stomach in the morning.1 ml of it was put into a disposable blood collection tube which had already been added EDTA-K2 anticoagulation,then the blood collection tube was slowly overturned 5-6 times for blending,finally the physiological indexes of the blood were measured;the other 1 ml was put into a disposable blood collection tube without anticoagulation,and there was not blending treatment,it was coagulated under natural conditions,finally the biochemical indexes of the blood were measured.All the samples were preserved at low temperature and submitted for testing timely.

The measurement of the physiological and biochemical indexes of blood

HC-3000 automatic hematology analyzer was adopted to measure white blood cell count (WBC),red blood cell count (RBC),red cell distribution width-coefficient of variation(RDW-CV),mean corpuscular hemoglobin concentration (MCHC),mean corpuscular hemoglobin (MCH),haemoglobin content (HGB),mean corpuscular volume(MCV),hematocrit(HCT) and blood platelet count (PLT)of samples.CS-400 fully automatic biochemical analyzer was used to measure 11 indexes of samples,such as lactic dehydrogenase (LDH),total calcium(CA),total cholesterol(CHOL),glucose(GLU),cholinesterase(PCHE),alkaline phosphatase (ALP),albumin(ALB),globulin (GLO),total protein(TP),glutamic-pyruvic transaminase(ALT)and glutamic oxalacetic transaminase(AST).The specific assay methods were based on the instruction of test kits.

Statistical analysis

SAS 6.12 statistical software was used for statistical analysis.

Results

The physiological indexes of White-Tibetan sheep

The seasonal variation of physiological indexes of White -Tibetan sheep was in Table1.The respiratory rate of White-Tibetan sheep was the highest in spring and the lowest in winter,which were (49.96±17.62)and(32.74±21.33) times/min,respectively;the differences on the respiratory rates between spring and autumn,summer and winter were not significant (P ＞0.05),and those in spring and autumn were extremely significantly higher than those in summer and winter (P＜0.01).For the body temperature of White -Tibetan sheep,that was the highest in summer and the lowest in winter,which were (39.73±0.31) and(39.27±1.05) ℃,respectively; the difference on the body temperature between summer and spring was not significant (P ＞0.05),which was significantly higher than that in autumn and winter (0.05＞P＞0.01); the difference between spring and autumn was not significant(P＞0.05),which was significantly higher than that in winter(0.05＞P ＞0.01); the difference between autumn and winter was not significant(P＞0.05).The heart rate of White-Tibetan sheep was the highest in spring and the lowest in autumn,which were(104.63 ±10.39) and (88.75 ±8.32)times/min,respectively; the difference on the heart rate between spring and summer was not significant (P＞0.05),which was extremely significantly high-er than that in autumn and winter (P＜0.01);that in summer was extremely significantly higher than that in autumn and winter (P＜0.01),the difference between autumn and winter was not significant(P＞0.05).

Table1 The seasonal variation of physiological indexes of White-Tibetan sheep(n=10)

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The physiological indexes of the blood of White-Tibetan sheep

The physiological indexes of the blood of White-Tibetan sheep in different seasons were in Table2.The indexes of MCH and MCHC were higher in autumn and winter,which were extremely significantly higher than those in spring and summer (P＜0.01).For the indexes of HGB and HCT,they were just in contrast to MCH and MCHC,because those in spring and summer were extremely significantly higher than those in autumn and winter(P＜0.01).The indexes of RBC and RDW-CV were the highest in summer,which were extremely significantly higher than those in spring,autumn and winter (P＜0.01),those in spring were extremely significantly higher than those in autumn and winter(P＜0.01),the difference between autumn and winter was not significant (P＞0.05).The index of WBC was the highest in winter,which was extremely significantly higher than those in autumn,spring and summer (P＜0.01),that in autumn was extremely significantly higher than that in spring and summer (P＜0.01),the difference between spring and summer was not significant (P ＞0.05).The index of MCV was the highest in autumn,which was extremely significantly higher than those in spring,summer and winter (P＜0.01),that in winter was extremely significantly higher than that in spring and summer (P＜0.01),and that in spring was extremely significantly higher than that in summer(P＜0.01).The index of PLT was the highest in summer,which had not obvious difference with that in autumn(P＞0.05)and was extremely significantly higher than that in spring and winter(P＜0.01),that in autumn was significantly higher than that in spring and extremely significantly higher than that in winter(P＜0.01),that in spring was significantly higher than that in winter(0.05＞P＞0.01).

The biochemical indexes of the blood of White-Tibetan sheep

The biochemical indexes of the blood of White-Tibetan sheep in different seasons were in Table3.The indexes of ALT,AST,TP,ALB,GLO and LDH were higher in autumn,in which the indexes of TP and GLO had not obvious difference between summer and autumn (P＞0.05),and those in summer and autumn were extremely significantly higher than those in spring and winter (P＜0.01);the index of AST in autumn was extremely significantly higher than that in spring,summer and winter (P＜0.01),the difference among spring,autumn and winter was not significant (P＞0.05);the index of ALThad not significant difference among spring,summer and winter (P＞0.05),and among autumn,spring and winter (P＞0.05),but that in autumn was extremely significantly higher than that in summer (P＜0.01);the index of ALB in autumn was significantly higher than that in summer(0.05＞P＞0.01) and extremely significantly higher than that in spring and winter (P＜0.01),the difference on that between summer and spring was not significant(P＞0.05),that in summer was extremely significantly higher than that in winter (P＜0.01),the difference between spring and winter was not significant(P＞0.05);the index of LDH had not obvious difference between summer and autumn (P＞0.05),that in autumn was significantly higher than that in winter (0.05＞P＞0.01)and extremely significantly higher than that in spring (P＜0.01),the difference between summer and winter was not significant (P＞0.05),that in summer was extremely significantly higher than that in spring (P＜0.01),the difference between spring and winter was not significant(P ＞0.05).The indexes of ALP,PCHE and GLU were higher in spring,in which ALP in spring was extremely significantly higher than that in summer,autumn and winter (P＜0.01),the difference among summer,autumn and winter was not significant(P＞0.05);PCHE index had not obvious difference between spring and winter (P ＞0.05),but that in spring and winter was extremely significantly higher than that in summer and autumn (P＜0.01),the difference between summer and autumn was not significant (P＞0.05);GLU index had not obvious difference between spring and winter (P ＞0.05),that in spring was extremely significantly higher than that in summer and autumn (P ＜0.01),the difference between winter and summer was not significant(P＞0.05),which was extremely significantly higher than that in autumn(P＜0.01),the difference between summer and autumn was not significant(P＞0.05).The index of CHOL was the highest in summer,which had not obvious difference with that in winter and autumn (P＞0.05)and was significantly higher than that in spring (0.05 ＞P ＞0.01),but the difference among spring,winter and autumn was not significant(P ＞0.05).The index of CA was the highest in winter,which was extremely significantly higher than that in spring,summer and autumn (P＜0.01),that in autumn was significantly higher than that in spring and summer (0.05＞P＞0.01),and the difference between spring and summer was not significant(P＞0.05).

Discussions

The climatic environment of plateau is worse than that of plain area,for example,the temperature difference between day and night is larger,the temperature and the effective oxygen content in the air change with the variation of season.To adapt to the climatic variation,the body of White -Tibetan sheep will form the corresponding adaptation mechanism.In this study,the seasonal variation of physiological and biochemical indexes of White -Tibetan sheep was measured,the body temperature of White-Tibetan sheep in spring and summer was relatively higher than that in winter and autumn; the respiratory rate is an important indicator measuring the adaptation of animals in the plateau,that of Tibetan sheep in spring and summer was lower than that in winter and autumn; the change of heart rate was consistent with the change of body temperature,namely the heart rate of spring and summer was relatively higher than that in winter and autumn.

Red blood cell,white blood cell and blood platelet in blood are three different cells,their quantity change and form distribution can be used to judge the physiological function of animal individual.The WBC index of white Suffolk sheep during the feeding period in the plateau in spring and summer was close to that of the transition period[1],but lower than that of white Suffolk sheep and Texcel-sheep fed in Gansu[5],Borderdale sheep[6],Duolang sheep[7],Large Tail Han sheep[8],and Liangshan semi-fine wool sheep[9],etc.,however,that in autumn and winter was higher than that in spring and summer as well as all mentioned sheep varieties; RBC index in spring and summer was higher than that of the transition period,the RBC index between domestic sheep and other sheep in China was very close.The difference on the HGB index between domestic sheep and other sheep in China was not significant.PLT index was in the normal range of domestic sheep in China.In four seasons,the indexes of WBC,MCV,MCH and MCHC showed the regular change,and those in autumn and winter were higher than those in spring and summer; the indexes of RBC,HCT and RDW-CV in spring and summer were higher than those in autumn and winter.

The indexes of AST,TP,ALB,GLO,LDH,CA and CHOL of white Suffolk sheep in winter and spring were in a relatively lower level,and in summer and autumn were in a relatively higher level; the indexes of PCHE,GLU and ALP in winter and spring were in a relatively higher level,while in summer and autumn were in a relatively lower level; the indexes of ALT and ALP in winter and spring were relatively higher,while in summer and autumn were relatively lower.Total protein is composed of albumin and globulin.Malnutrition or consumption increasing will cause the decrease of total protein[10].In summer and autumn,Tibetan sheep can get adequate nutrients from the pasture,but in winter and spring,the pasture in plateau grassland is severely lacking,which will cause the severe shortage of protein nutrients,thereby generating the decrease of total protein,albumin and globulin,and liver metabolism.The cholinesterase of sheep is a composite of parenchyma cell of liver,the nutrients for white Suffolk sheep in summer and autumn are adequate,thus the level of cholinesterase is in a lower level,and the physiological metabolism is normal,however,in winter and spring,there is a severe shortage of grass,the level of cholinesterase is in a higher level,thereby the metabolic function of liver is improved,so as to meet the nutritional requirement for the pasture.

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