Regulation And Molecular Mechanism Of Chronic Cold Stress On Sheep Fur Tissue

Cold stress has an important impact on the sheep industry.Fur is an important functional tissue for sheep to adapt to low temperature environments.However,the molecular mechanism of fur structure,function and utilization under cold stress is still unclear.Therefore,this study took the cold-resistant coarse wool breed Hulun Buir sheep ewes and the not cold-resistant lambskin breed Hu sheep ewes as objects,a total of 24,divided into four groups,namely the normal temperature Hu sheep group(n=6),the normal temperature Hulun Buir sheep group(n=6),the low temperature Hu sheep group(n=6)and the low temperature Hulun Buir sheep group(n=6).The experimental period includes an acclimation period(7 days),cold room cooling period(decreased by 5℃ every two days,a total of 14 days)and a formal trial period(45 days).Using chronic cold stress simulation,through tissue structure and transcriptomic analysis,the sheep fur traits and related genes were analyzed to respond to chronic cold stimulation,which providing data and application basis for further elucidating the response mechanism of chronic cold stress in different fur types sheep.The main results of this study are as follows:1.Comparing and analyzing Hulun Buir sheep and Hu sheep fur traits at low temperature(-20℃)and normal temperature(15℃),it was concluded that compared with Hulun Buir sheep at normal temperature,the wool length at low temperature was extremely significant higher than normal temperature(P<0.01),and the hair follicle density at low temperature was extremely significant smaller than normal temperature(P<0.01).There were no significant difference in wool yield,coarse and fine wool mean fiber diameter,single staple strength,grease content and cashmere percentage.The wool yield in Hulun Buir sheep at low temperature was extremely significant higher than Hu sheep(P<0.01),and the difference in other fur traits were not significant.The hair follicles density in Hulun Buir sheep at normal temperature was extremely significant higher than Hu sheep(P<0.01),the fine wool mean fiber diameter was significantly smaller than Hu sheep(P=0.04),and the difference in other wool traits were not significant.Changes in these fur traits were presumed to be related to adaptation to cold environments.2.Using high-throughput sequencing,transcriptome analysis and other means,the result found that:Compared with Hulun Buir sheep at normal temperature,seventeen genes related to fur traits were screened out at low temperature.Compared with Hu sheep at normal temperature,two genes related to fur traits were screened out at low temperature.Compared with Hu sheep at low temperature,six genes related to fur traits were screened out in Hulun Buir sheep.Compared with Hu sheep at normal temperature,six genes related to fur traits were screened out in Hulun Buir sheep.It was speculated that Hulun Buir sheep was more sensitive to temperature change than Hu sheep.This experiment found that the fur traits in Hulun Buir sheep and Hu sheep at low and normal temperature,and screened differentially expressed genes through the skin transcriptome,which providing a theoretical basis for further elucidating the response mechanism of chronic cold stress in sheep.