Study On The Growth And Development Mechanism Of Miniature Type Of Tiantai Cattle

Tiantai cattle is a local preserved cattle population in Zhejiang Province.Tiantai Cattle is distributed in Tiantai County,Taizhou City,Zhejiang Province.It is a fine meat-type cattle In history,Tiantai County has inconvenient transportation,poor water conservancy conditions,and overlapping terraces in mountainous areas.The local cattle are resistant to heat and crude fodder,and they are agile in movement.They have strong adaptability to the mountainous terraces with complex terrain and are easy to graze.After a long period of natural selection and artificial breeding,a local cattle breed is formed.Among the Tiantai cattle population,according to the standard of body height,bulls lower than 95 cm or cows less than 90 cm in the 1.5-year-old,are classified as miniature type.After nearly ten years of population management and selective breeding,a tiny group named Shifeng miniature cattle was gradually formed.Many field investigations in the past three years have shown that Shifeng liniature cattle,which is concentrated and self-promoting in Shifeng miniature Cattle Cooperative in Pingqiao Town,Zhejiang Province,is the only miniature cattle group in China,which could be a valuable genetic resource of domestic cattle in China.This study explored the effects of cellular factors and genetic polymorphisms affecting body growth and development on body shape,and studied on the regulation mechanism of body formation of Shifeng miniature cattle based on RNAseq method,to provide the basic biochemical information of physiology in Shifeng miniature cattle,and try to explain the formation mechanism of miniature body type.Experiment 1.Effect of growth and develop1ent related factors on body shapeA total of 18 healthy 12-month-old healthy cattle were selected through the livestock and poultry genetic resources conservation farm.Among them,12 cows included 4 small-sized cows,8 normal-type cows,6 bulls,small bodies and normal body types.At 3 heads,blood biochemical indicators(GHS GHR,IGF-1,cAMP,PTH,TGF-B)were measured by ELISA enzyme-linked immunosorbent assay kit to analyze the changes of blood biochemical parameters.The results showed that the hormone levels of small body types in the three hormone levels of growth hormone receptor(GHR),cyclic adenosine monophosphate(cAMP)and parathyroid hormone(PTH)were significantly higher than those of gross hormones(P<0.05).There were no significant differences in growth hormone(GH),insulin-like growth factor-1(IGF-1)and transforming growth factor beta(TGF-?)(P>0.05).In the bull group,the levels of hormones in the two hormone levels of cAMP and TGF-? were significantly higher than those of the small body(P<0.05).Growth hormone(GH),growth hormone receptor(GHR),insulin-like growth factor-1(IGF-1),and parathyroid hormone(PTH)were not significantly different(P>0.05).Experiment 2.Effect of polymorphism of GH locus on body typeBy selecting 12 Tiantai cattle,5 Leiqiong cattle,and 4 Mongolian cattle,the genetic characteristics of the GH gene of Shifeng miniature cattle and its association with small body type were investigated.The results showed that the literature mentioned "dwarfing" allele T641 at GH gene locus was not found in Shifeng miniature cattle.A mutation of the SNP C649A was detected in the GH gene coding region in Shifeng miniature cattle.The mutation on the GH gene may be an important cause of low development,which may alter the effects of GH and receptor binding,resulting in a decline in normal function.Experiment 3:Research on the regulation mechanism of body formation based on RNAseq methodA total of 15 cattle of about 12 months old,6 healthy Shifeng miniature cow,4 ordinary Tiantai cow,3 Shifeng miniature cattle bulls,and 2 ordinary bulls,were sampled from the Tiantai Cattle Preservation Farm in Pingqiao Town,Tiantai County,Zhejiang Province.The transcriptome(RNA-seq)sequencing and bioinformatics analysis techniques were used to screen differentially expressed genes,and the key genes of growth and development of Shifeng miniature cattle were further explored and their regulatory mechanisms were explored.Results showed that the transforming growth factor gene(TGFB2)enriched in the TGF-? signaling pathway and the insulin growth factor binding protein gene(IGFBP3)enriched in the P53 signaling pathway are in a down-regulated state in the Shifeng miniature cattle.It may inhibit the expression of transforming growth factor and insulin growth factor in Shifeng miniature cattle.Thus,the effect of growth factors is weakened,thereby inhibiting the effects of growth hormone and thyroid stimulating hormone,causing growth and development disorders,resulting in smaller size and slow growth.