Comparative Analysis Of Milk Composition And Multi-omics Between Dairy Meade,Small-tailed Han And The Hybrid Progeny

Ovine milk has been paid increasing attentions for its high concentrations of major nutrients and multiple biological functions,with broad market prospect.Until now,there is no specialized dairy sheep breed in China.DairyMeade(DM)sheep is a type of dairy sheep breed from New Zealand.It is characterized with high milk production,fast growth rate,and high prolificacy.These advantages make it be an ideal male parent for the breeding of new localized dairy sheep.In this study,the milk components comparation of different generations was analyzed.And then the proteomic through tandem mass tag(TMT)approach and metabolomic through UPLC-Q-TOF-MS/MS non-targeted approach were analyzed to explore the mechanism of different lactation traits.The main results were as follows:1.The milk composition analysis results showed that the fat in F1 milk was the highest,followed by STH,DM and F2 milk;the protein in STH milk was the highest,followed by F1,DM and F2 milk;the lactose in F2 milk was the highest,followed by DM,F1 and STH milk.The content of vitamin C,vitamin B2 and pantothenic acid in STH milk were the highest,while the content of Vitamin B12 and folic acid in F1 milk were the highest.In terms of minerals,the content of calcium,phosphorus,zinc and selenium in STH milk were the highest,while the content of copper and potassium in DM milk were the highest.The essential amino acids in the STH milk were the highest,followed by F1,DM,F2.Relative content of functional fatty acids that include alpha linolenic acid,MUFA,PUFA,ω-3 fatty acids and ω-6 fatty acids in the F2 milk was the highest.2.The proteomic analysis results showed that a total of 655 whey proteins were identified.Based on FC≥1.5 and P<0.05,46,29 and 23 differentially expressed proteins were identified in DM vs STH,F1 vs DM and F1 vs STH comparison,respectively.The functional analysis of the differential expressed proteins showed that S100A2 and CREG1 were related to milk production traits.FABP3 and apolipoprotein were related to milk fat traits,and XDH,CD74 and CD84 were related to the disease resistance traits.3.Metabolomics analysis showed that a total of 14,739 metabolites(9085 in positive ion mode and 5654 in negative ion mode)were detected.Based on FC≥2 or<0.5,P<0.05 and VIP>168,102 and 19 differential abundant metabolites were identified in DM vs STH,F1 vs DM and F1 vs STH comparison.The functional analysis of differential abundant metabolites showed that L-carnitine and phosphatidylethanolamine were related to the milk fat trait.Nucleotides and energy substances were related to lactation performance.UDP-D-glucose were related to the lactose trait.Phosphatidylcholine and pyroglutamate were associated with disease resistance and immune function.In total,although there were some differences of milk between different generations,they both contain high concentrations of nutrients.The differences between proteome and metabolome of different generations partially explained the formation mechanism of lactation traits in dairy sheep.The results can provide reference for the exploration of the mechanism of differences in lactation traits between dairy animals,provide theoretical data for breed selection of new dairy sheep and provide the theoretical basis for the breeding and industrialization of local dairy sheep in China.