Characteristic and Functional Analysis of Rumen Microbial Communities in Holstein Cows with Different β-Casein Genotypes
β-casein is one of the most important proteins in milk,and there are two major genotypes,Al and A2,in Holstein cows.In order to investigate the differences of rumen microbial communities of Holstein cows with different β-casein genotypes,15 Holstein cows with genotypes Al Al,A1A2 and A2A2 in good condi-tion and the first parity were selected in the experiment(milk fat percentage and milk protein percentage of all genotypes were similar).After rumen fluid collection,metagomic sequencing was performed by Illumina HiSeq 2000 platform,Diamond 0.9.7 software was used for classification and functional annotation,and the composition and function of rumen microbial communities of three genotypes of dairy cows were analyzed.The results showed as follows:1)the characteristic microorganisms in rumen of cows with genotype A1A1 were Intestinibaculum,Dialister,Klebsiella and Acinetobacter,and so on;the characteristic microorganisms in ru-men of cows with genotype A1A2 were Paraprevotella and Paraprevotella xylaniphila of Prevotellaceae;and the characteristic microorganisms in rumen of cows with genotype A2A2 were Acetobacter and Xanthomonas,and so on.2)The rumen of cows with genotypes A1A2 and A2A2 was rich in enzymes related to lignocellu-lose and cellulose degradation;the number of genes involved in starch and sucrose metabolism,fatty acid bio-synthesis,protein digestion and absorption,arginine and proline metabolism and RNA degradation pathways were more in rumen of cows with genotype A1A2,and the rumen of cows with genotype A2A2 had more genes involved in the regulatory pathway of inflammatory mediators.It can be concluded that the rumen marker microorganisms of Holstein cows with genotype A1A1 are Intestinibaculum and Dealisteria,which may be po-tentially associated with reduced methane emissions and β-casein type A1,as well as some diseases;the rumen marker microorganism of cows with genotype A1A2 is Prevotellaceae,which may promote dietary digestion;and the rumen marker microorganism of cows with genotype A2A2 is Acetobacter,and its relative abundance has a regulating effect on milk fat content.[Chinese Journal of Animal Nutrition,2024,36(1):537-550]
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