Genetic Diversity Estimation And Meat Nutrient Characteristics Of Hechuan White Goat

Goats（Capra hircus）,as one of the earliest domesticated animals of humans,play an important role in human social civilization,agricultural civilization,and economic development.Goats play an important role in providing meat,fresh milk,fur,and other products and living materials necessary for human life.At present,based on official data from FAO in 2007,more than 150 major goat breeds and breed groups are identified worldwide,which are primarily divided into six categories based on production direction:cashmere goats,leather goats,meat goats,wool goats,dairy goats,and combined goats.As an inherent local genetic resource in Chongqing,Hechuan white goat has excellent performance in many aspects such as reproductive performance,meat production performance and plate skin quality,especially with the potential of highquality meat sheep.Due to the long-term one-sided pursuit of product production performance and economic benefits,the population of Hechuan white goat genetic resources has decreased sharply,and the purity and performance have decreased to varying degrees,and it is facing threats such as loss of excellent genes and performance degradation.Therefore,because of strengthening the protection of Hechuan white goat germplasm resources and the mining of genetic characteristics,promoting the innovative utilization of Hechuan white goat germplasm resources is the key to improving the quality of animal husbandry economy in production areas.In this study,14 microsatellite marker sites and mitochondrial DNA D_Loop region sequences were used to evaluate the genetic diversity of Hechuan white goat population.In addition,the muscle nutrient characteristics of Hechuan white goat and the correlation among mutton nutrition,rumen metabolites,and microorganisms were explored through metabonomics and metagenomics,which provided a basis for the subsequent improvement of the quality characteristics of Hechuan white goat meat and laid the foundation for the subsequent development of a screening system for the rapid identification of goat meat quality biomarkers.The results of this study are as follows:（1）In this study,a total of 105 alleles were identified in the Hechuan white goat population using 14 microsatellite genetic marker（STR）sites,and the polymorphic information content distribution of each site ranged from 0.2262（SRCRSP15）to 0.8103（MAF065）.Of the 14 STRs in the Hechuan white goat population,six were significantly out of equilibrium（p <0.05）.The analysis results of group inbreeding coefficient and group bottleneck effect showed that no significant inbreeding was found in the Hechuan white goat population,and the bottleneck effect occurred.The results of pair-wise difference（FST）analysis showed a significant genetic difference between the Hechuan white goat and the Chuandong white goat populations（FST = 0.0426,p < 0.05）,indicating that the two groups of Hechuan white goat and eastern Sichuan white goat should be regarded as two local native goat genetic resources with independent genetic backgrounds.（2）Based on the evaluation results of genetic diversity parameters in the D_Loop area,a total of 72 SNP mutations were detected in 96 individuals in the Hechuan white goat population,constituting a total of 30 haplotypes（Hap₁ to Hap₃0）.Based on the results of the phylogenetic tree,30 haplotypes belonged to the known maternal mitochondrial genetic clades A,B1,and B2 of goats.Tthe nucleotide polymorphism（Pi）D_Loop Hechuan white goat population was 0.00205,and the haplodiversity was 0.8761.This result indicates that the maternal genetic diversity of Hechuan white goat population is abundant.（3）In the detection of muscle nutrition content of Hechuan white goat,the EAA/TAA value was 46.18%,which is higher than the standard proposed by the FAO/WHO model,so Hechuan white goat lamb is an ideal source of high-quality meat protein.Palmitic acid accounted for the highest proportion of saturated fatty acids（24.77%± 1.86%）,and oleic acid accounted for the highest proportion（41.01% ± 3.33%）among unsaturated fatty acids.In addition,Glutamate and lysine content were significantly negatively correlated with intramuscular fat（p < 0.05）.（4）Based on the results of metabolomic cluster analysis of rumen contents of Hechuan white goat,a total of 965 metabolites were detected in rumen contents of Hechuan white goat,According to the law of expression of metabolites,they are clustered into seven modules of different colors.Then,based on correlation analysis of rumen content metabolites and nutritional composition indicators of mutton detected in this institute,estriol（MEDP2043）,riboflavin（MEDP0250）,pantothenic acid（MEDN0245）and ferulic acid（MEDN1880）were significantly correlated with the content of minerals,amino acids and fatty acids.（5）Rumen metagene detection between the two groups with different fatty acid contents of Hechuan white goat showed that the microorganisms among the five groups with high and low fatty acid contents had a similar overall structure and composition at three levels: phylum,genus,and species.However,at the species level,significant differences in microbial varieties and abundance were observed among different fatty acid groups.This study found that the rumen microbial species of Hechuan white goat correlated with fatty acid content.The types of microorganisms in the rumen of Hechuan white goats with different fatty acid content are different.The abundance of bacteria in Bacteroidetes_bacterium,Ruminococcaceae_bacterium_P7,Eubacterium_ruminantium,and Prevotella_bacterium was significantly correlated with fatty acid content.As a local native goat genetic resource with independent genetic background,Hechuan white goat is rich in maternal genetic diversity,and fresh meat is rich in a variety of amino acids and minerals,which can be used as an ideal source of high-quality meat protein.Through the analysis of the association between nutrients,rumen contents metabolome and metagenomic in Hechuan white goat meat,it was found that the content of various metabolites in the rumen content of Hechuan white goat was significantly correlated with the content of minerals,amino acids and fatty acids,and the species and abundance of rumen microorganisms were significantly correlated with the content of fatty acids.This study provides data support for the future conservation and utilization of Hechuan white goat,which is helpful for the development of biomarker system for subsequent mutton quality identification.