Study On Effects Of Thermal Environment On Weight Gain Performance And Physiological Indexes Of Sheep

After the rapid development of the sheep breeding industry in recent years,the scale has been greatly improved.However,it has always existed and been ignored for long that the environmental factors diminish the production of sheep.This problem is especially noticeable during the high temperature in summer and the low temperature in winter when the growth and health of sheep are severely affected.Thus,it is important to study how sheep production responds to extreme temperatures,which help us ascertain the theoretical basis for exploring nutrition and management measures to alleviate the stress caused by low temperature environment and high temperature environment.So,in the current experiments,sheep were used as experimental animals to study the physiological changes of sheep in different environments?both high-and low-temperature environments?.These parameters include basic physiological indicators,rumen fermentation,microbial diversity,blood biochemical indicators,and expression of heat shock protein.This study provides a theoretical basis for the regulation of the breeding environment in actual production.Exp.1 Effects of Low Temperature Environment on Weight Gain Performance and Physiological Indexes of LambsThe present experiment was conducted in the teaching ranch of Inner Mongolia Agricultural University in January,2017.A total of 18 healthy male Dorper×Han lambs?5-month-old?were selected and randomly divided into three groups,including indoor-preference-temperature group?daily temperature range 6.95??10.92??,indoor-natural-temperature group?daily temperature range-0.41 ??6.30??and outdoor-natural-temperature group?daily temperature range-21.91 ??0.99??.Each group contained six lambs,and the experiment lasted for 28 days.The experimental results are showed as follows:Feed intake was increased during the low temperature environment,and the daily gain was decreased,resulting in feed-gain ratio increaseing,also decreased the apparent digestibility of crude protein,crude fat,crude ash,calcium and phosphorus.The physiological response such as skin temperature?head,ear,abdomen and leg?,rectal temperature and respiratory rate were significantly decreased.Under low temperature environment,the level of total protein,albumin,glucose,cholesterol and low-density lipoprotein cholesterol in serum were decreased by up-regulating insulin,adrenocorticotropic hormone,cortisol level in serum,changing sugar metabolism,lipid metabolism and protein metabolism.Meanwhile,the level of inorganic salt ion sodium in serum was decreased and chlorine in serum was increased.Under low temperature environment,the abundance of phylum Bacteroidetes genus,norank_fRuminococcaceae,genus Saccharofermentans,genus norank_cBacteroidete_VC2.1_Bac22,genus Blastomonas,genus Paeniclostridium,genus Fibrobacter and genus Acidaminococcus were increased,the abundance of phylum Actinobacteria and genus norank_fPrevotellaceae were decreased.Additionally,the concentration of total volatile fatty acids,acetic acid and propionic acid in rumen of lambs were increased.Lambs increased the concentration of HSP90 in serum of lambs through regulating the gene expression of HSP90 and HSP110 in blood mononuclear cells by regulating KLF4 pathway at the low temperature environment.Exp.2 Effects of Low Temperature Environment on Weight Gain Performance and Physiological Indexes of EwesThe present experiment was carried in the teaching ranch of Inner Mongolia Agricultural University in January,2017.A total of 18 healthy Mongolian ewes?3-year-old?were randomly divided into three groups,including indoor-preference-temperature group?daily temperature range 5.8??10.34??,indoor-natural-temperature group?daily temperature range 1.07??6.18??and outdoor-natural-temperature group?daily temperature range-21.91 ??0.99??.Each group contained six ewes,and the experiment lasted for 28 days.The results are showed as follows:The daily gain of adult ewes was decreased at low temperature environment period.However the apparent digestibility of neutral detergent fiber and acid detergent fiber were improved.The physiological response such as skin temperature?head,ear,abdomen and leg?,rectal temperature and respiratory rate was decreased markedly.Under low temperature environment,gluconeogenesis was inhibited and lipid metabolism was increased by up-regulating the activity of adiponectin,insulin and thyroxine,leading to a decreased level of low density lipoprotein cholesterol in serum.In addition,muscle metabolism was inhibited and caused a decrease the level of serum creatinine.At the same time,low temperature environment caused the declining of the level serum calcium and chloride.During low temperature environment,the abundance of genus Ruminococcus₂,genus Ruminococcaceae_NK4A214_group,genus Mogibacterium,genus Lachnoclostridiu-m₁ and genus[Eubacterium]_hallii_group were increased,whereas the abundance of genus Selenomonas was decreased.In addtion,the concentrations of volatile fatty acids expect propionic acid in rumen of ewes were increased.Futhermore,HSP90 in serum of ewes were increased under the low temperature,resulting in up-regulating the gene expression of HSP60,HSP70,HSP90 and HSP110 in blood mononuclear cells by regulating HSF1-KLF4 pathway.Exp.3 Effects of High Temperature Environment on Weight Gain Performance and Physiological Indexes of LambsThe present experiment was carried out in the education ranch of Inner Mongolia Agricultural University in August,2017.A total of 18 healthy Dorper×Mongolian male lambs?5-month-old?were randomly divided into three groups,including indoor-preference-temperature group?daily temperature range 17.87??25.41 ??,indoor-natural-temperature group?daily temperature range 21.30??28.74??and outdoor-natural-temperature group?daily temperature range 12.14 ??29.68 ??.Each group contained six lambs,and the test lasted for 28 days.The results are showed as follows:Daily gain and food intake of lambs were inproved under hyperthermia environment,and feed-gian ratio was enhanced.The digestibility of dry matter and ether extract were decreased.The physiological response such as skin temperature?head,ear,abdomen and leg?,rectal temperature and respiratory rate was increased dramatically.The increasing of adrenocorticotropic hormone activity inhibited the secretion of insulin,leptin and adiponectin,strengthened sugar metabolism,and reduced lipid metabolism,resulting in an increaseing level of serum glucose and a decreasing level of free fatty acid in serum.Moreover,the levels of inorganic salt ion chloride concentration in serum of lambs were increased at hyperthermia environment.During hyperthermia environment,the abundance of genus Ruminococcaceae_UCG-010,genus norank_f Bacteroidales_UCG-001,genus Erysipelotrichaceae_UCG-004,genus Lachnospiraceae_NK4A136_group were increased.However,the abundance of genus Staphylococcus was decreased.The concentration of isobutyric acid in rumen of lambs was increased.At the same time,HSP70,HSP90 and HSP110 gene expression in blood mononuclear cells were up-regulated by HSF1-KLF4 pathway in hyperthermia environment,which resulted in the enhancement of HSP70 and HSP90 concentration in serum.Exp.4 Effects of High Temperature Environment on Weight Gain Performance and Physiological Indexes of EwesThe present experiment was carried out in the education ranch of Inner Mongolia Agricultural University in August,2017.A total of 24 healthy Mongolian ewes?3-year-old?were randomly divided into four groups,including indoor-preference-temperature group?daily temperature range 17.53??22.44??,indoor-natural-temperature group?daily temperature range 21.30??28.74??,indoor-high-temperature group?daily temperature range 23.16??31.03??and outdoor-natural-temperature group?daily temperature range 16.46??30.21??.Each group contained six ewes,and the test lasted for 28 days.The results are showed as follows:The body daily weight and intake of adult ewes were reduced under hyperthermia environment.The apparent digestibility of crude protein and ether extract were increased and the apparent digestibility of phosphorus was reduced.The physiological response such as skin temperature?head,ear,abdomen and leg?,rectal temperature and respiratory rate were increased significantly.The change of insulin concentration increased the activity of adrenocorticotropic hormone and cortisol,and inhibited the secretion of adiponectin,leptin,tri-iodo-thyronine and thyroxine to regulate the ewes' metabolic intensity under hyperthermia environment.The activity of total protein and globulin were affected by hyperthermia environment.Addtionally,the concentration of creatinine,cholesterol,triglyceride,high density lipoprotein were increased,while the content of non-esterified fatty acid was opposite.The level of potassium,magnesium and chlorine in serum were reduced,while the level of calcium and phosphorus were increased under hyperthermia environment.At the same time,the abundance of genus Ruminococcaceae_NK4A214_group,genus Candidatus_Saccharimonas,norank_pSR1_Absconditabacteria,genus Fibrobacter,genus[Ruminococcus]_gauvreauii_group,genus Marvinbryantia,genus[Eubacterium]_nodatum_group and genus Blautia were increased,wheras the abundance of genus Lachnospiraceae_NK4A136_group was decreased.The concentration of total volatile fatty acids,acetic acid,butyric acid and ratio of acetate and propionate were increased,but isobutyric acid in rumen of ewes was decreased.In addition,the gene expression of HSP60,HSP90 and HSP110 was regulated by the HSF1 pathway of blood mononuclear cells at hyperthermia environment,which resulted in the increasing of serum HSP90 concentration in ewes.