| This experiment was conducted to study the effects of the diet energy and protein levels on mRNA expression of nutrient transporters in the small intestine duodenum and muscle of Tan sheep,to investigate its transport regulation mechanisms and provide theoretical support for scientific feed manufacturing of Tan sheep.A total of 112 healthy Tan sheep(half male and half female),with similarly initial live weight,were randomly divided into four groups,with four replicates in each group,and seven sheep were used in per replicate.Each group was fed diets with different level but same ratio of energy and protein respectively(standard diet referenced the Feeding Standard of Meat-producing Sheep and Goats(NY/T816-2004)): 84% standard level(group ?),96%standard level(group ?),108% standard level(group ?)and 120% standard level(group IV).The test period were divided into two stages by body weight of sheep: 29~35 kg and36 ~ 40 kg.At the end of each stage,one sheep was slaughtered at each replicate,and duodenuml samples and muscle samples were collected to study mRNA relative expression of SGLT1,GLUT4,GLUT5,PepT1,CAT1,EAAT3,EAAT5,FATP1 and FATP4 genes by Real-time Quantitative PCR.The main results shows that as follows:1.Studies of different dietary energy and protein levels on mRNA expression of glucose transporters in the duodenum and muscle of Tan sheepThe results indicated that the expression levels of SGLT1 gene mRNA in duodenum was the highest in group ?(P<0.05)when at the end of 29~35 kg stage.At the end of 36-40 kg stage,SGLT1 m RNA expression levels had no difference in the four groups(P>0.05).In muscle,SGLT1 mRNA expression level increased with the rise of energy and protein levels in both stages(P<0.05).In duodenum,at the end of 29~35 kg stage,GLUT4 gene mRNA expression levels had no difference in the four groups(P>0.05);at the end of 36~40 kg stage,GLUT4 mRNA expression level increased with the rise of energy and protein levels(P<0.05).In muscle,the expression level of GLUT4 gene mRNA were highest in group ? in both stages(P<0.05).The expression of GLUT5 gene mRNA did not show any regularity at the two experimental stages.2.Studies of different dietary energy and protein levels on m RNA expression of small peptides transporters in the duodenum and muscle of Tan sheepIn duodenum,at the end of 29~35 kg stage,PepT1 mRNA expression firstly decreased and then increased with diet energy and protein levels increase(P<0.05).At the end of 36~40kg stage,PepT1 mRNA expression levels had a downward trend after rising with diet energy and protein level increase(P<0.05).In muscle,PepT1 gene mRNA expression levels had no difference in the four groups at the two experimental stages(P>0.05).3.Studies of different dietary energy and protein levels on m RNA expression of amino acids transporters in the duodenum and muscle of Tan sheepIn duodenum,at the end of 29~35 kg stage,CAT1 mRNA expression levels in group IV was significantly higher than other groups(P<0.05).And CAT1 mRNA expression levels in group III was significantly lower than group II at the end of 36~40 kg stage(P<0.05).In muscle,CAT1 mRNA expression levels in group III was significantly lower than other groups at the end of 29~35 kg stage,and CAT1 gene mRNA expression levels had no difference in the four groups at the end of 36~40 kg stage(P>0.05).In duodenum,at the end of 29~35 kg stage,EAAT3 m RNA expression levels in group III was significantly higher than other groups(P<0.05).EAAT3 mRNA expression levels had a significantly rise trend with diet energy and protein level increase at the end of 36~40 kg stage(P<0.05).In muscle,with diet energy and protein levels increase,EAAT3 m RNA expression levels had a significantly rise trend at the two experimental stages,and in group I expression levels was lowest.And in duodenum,EAAT5 mRNA expression firstly increased and then decreased with diet energy and protein level increase at the end of 29~35 kg stage(P<0.05),and at the end of36~40 kg stage,EAAT5 mRNA expression had a down trend.In muscle,EAAT5 mRNA expression in group II was highest at the end of 29~35 kg stage,and its expression levels in group III was significantly higher than other groups at the end of 36~40 kg stage(P<0.05).4.Studies of different dietary energy and protein levels on m RNA expression of fatty acid transporters in the duodenum and muscle of Tan sheepAt the two experimental stages,FATP4 mRNA expression had a rise trend in duodenum,and FATP1 mRNA expression had a fall and then a rise trend with diet energy and protein levels increase in muscle(P<0.05).In conclusion,diets with different levels of energy protein have a certain degree of influence on the mRNA expression of nutrient transporters in the small intestine duodenum and muscle of Tan sheep,which can change the absorption and utilization of the nutrients to adapt to Tan sheep's growth and development. |
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