Comparative Analysis of the Ultrastructure, Bubble Pores, and Composition of Eggshells of Dwarf Layer-White and Guinea Fowl.

The decrease in eggshell quality seriously affects production efficiency. Guinea fowl (GF) eggs possess strong eggshells because of their unique crystal structure, and few systematic studies have compared laying hen and GF eggs. Sixty eggs were collected from both 40-week-old Dwarf Layer-White (DWL-White) laying hens and GF, and the eggshell quality, ultrastructure, bubble pores, and composition were measured. The results showed that the DWL-White eggs had a higher egg weight and a lower eggshell strength, strength per unit weight, thickness, and ratio than the GF eggs (p < 0.01). There were differences in the mammillary layer thickness ratio, the effective layer thickness ratio, the quantity of bubble pores (QBPs), the ratio of the sum of the area of bubble pores to the area of the eggshell in each image (ARBE), and the average area of bubble pores (AABPs) between the DWL-White and GF eggs (p < 0.01). The composition analysis demonstrated that there were differences in the organic matter, inorganic matter, calcium, and phosphorus between the DWL-White and GF eggs (p < 0.01). There were positive associations between the mammillary knob number in the image and the QBPs and ARBE and a negative correlation with the AABPs in the DWL-White eggs (p < 0.01). This study observed distinctions that offer new insights into enhancing eggshell quality.

Eggshell translucency in late-phase laying hens and its effect on egg quality and physiological indicators.

Eggshell translucency severely affects external egg quality, and variations in the eggshell or eggshell membrane are considered the structural basis of the trait. Research has shown that 1.85% additional mixed fatty acids in the diet would greatly decrease the occurrence of eggshell translucency. Only a few studies have examined the phenotypic regularity of eggshell translucency with the increasing age of hens. Therefore, two strains, 1139 Rhode Island Red-White (RIR-White) and 836 Dwarf Layer-White (DWL-White), were used, and from each strain, 30 hens each that consecutively laid translucent or opaque eggs at 67 wks of age were selected. Subsequently, eggshell translucency, internal quality and external quality of eggs, and total cholesterol, albumin, calcium binding protein and other physiological indicators related to lipid, lipoprotein, and calcium metabolisms at the 75th, 79th, and 83rd wks of age in the late phase of the laying cycle were determined. Results: (1) In terms of flocks, for both strains, the translucency scores of the translucent groups were significantly higher than those of the opaque groups (P < 0.05); in terms of individuals, 81.1% RIR-White and 82.8% DWL-White hens consecutively laid eggs of the same or similar translucency, indicating the stability of the trait with increasing hen age; (2) In RIR-White, the eggshell strength of the translucent group at 75 weeks was significantly higher than that of the opaque group (P < 0.05); in DWL-White, the eggshell membrane thickness of the translucent group at the 75th and 83rd weeks was significantly lower than that of the opaque group (P < 0.05); (3) Compared to the opaque groups, the translucent groups had lower total cholesterol content in both RIR-White and DWL-White, lower albumin content in DWL-White at the 79th weeks (P < 0.05), and higher calcium-binding protein (CALB1) in RIR-White at the 83rd weeks (P < 0.05). In summary, this study illustrates the stability of eggshell translucency in late-phase laying hens and provides a reference of physiological indicators for exploring the formation of translucent eggs.

Effect of natural garlic essential oil on chickens with artificially infected Eimeria tenella.

Chicken coccidiosis is a kind of parasitic protozoosis caused by Eimeria parasitizing in the chicken intestinal epithelial cells. Eimeria tenella is considered as a significantly virulent and harmful parasite. At present, drug resistance remains a major problem and a large number of drug residues have been found to be produced in the treatment of the disease. Hence, novel strategies are needed to avoid the harmful effects caused by the generation of various chemical drug residues to the human body and also reduce the economic loss caused by coccidiosis to the chicken industry. In this study, natural garlic essential oil was used to control Eimeria tenella infection. The anticoccidial index (ACI) was calculated according to the clinical symptoms, body weight gain, oocyst excretion and cecal lesions. The immune organ index and serum biochemical indexes were measured to verify the possible anticoccidial effects. The results showed that: compared with the infected group, continuous feeding of different doses of natural garlic essential oil could significantly reduce the clinical symptoms, cecal lesions, the number of oocysts, but increase the weight of sick chickens, and effectively improve the intestinal functions. Moreover, compared with diclazuril control group, 0.06 mL/L garlic essential oil exhibited similar anticoccidial index. The content of immune organ index, serum biochemical index IgM, IgG and IgA in 0.06 mL/L garlic essential oil group was the highest, which indicated that garlic essential oil had a significant tendency to improve the immune function of the chickens. This study also showed that the natural garlic essential oil exhibited the same beneficial effects as that of diclazuril on chicken coccidiosis, and the anti-coccidiosis index of 0.06 mL/L garlic essential oil was favorable. Thus based on the above evidences and its relatively low cost, garlic essential oil can be potentially be used as an efficient anti parasitic drug.

The relationship between the mTOR signaling pathway and ovarian aging in peak-phase and late-phase laying hens.

The molecular mechanisms underlying reproductive aging in avian species are poorly understood. Previous studies have shown the importance of mechanistic target of rapamycin (mTOR) signaling pathway in aging. In this study, we investigated the relationship between the mTOR signaling pathway and ovarian aging in the peak phase and late phase of egg production in laying hens. The egg production rate and egg quality were tracked for 5 consecutive weeks in 30-week-old and 70-week-old Dawu Jinfeng hens (N = 30/group). During the peak phase (week 35) and late phase (week 75), antioxidant and immune indicators were detected by enzyme-linked immunosorbent assay, and mTOR signaling-related genes (CLIP-170, GRB10, LIPIN-1, ATG1, 4E-BP1, S6K, PKC, RHO, and SGK1) were detected in the follicles by quantitative reverse transcription-PCR technology. The protein expression of key genes (mTOR, PKC, 4EBP1) was evaluated by Western blot analysis. The egg production rate and the antioxidant indexes superoxide dismutase and glutathione peroxidase and the levels of total antioxidant capacity and immunoglobulins (IgM and IgG) were significantly higher at week 35 than those at week 75 (P < 0.01), while malondialdehyde levels were significantly lower (P < 0.01). At week 75, there were fewer follicles in the different stages of development than were detected at week 35. The number of white follicles (large and small) and primary follicles were significantly higher at week 75 than those detected at week 35 (P < 0.01). The mRNA expression of avTOR, CLIP-170, GRB10, LIPIN-1, 4E-BP1, S6K, RHO, and SGK genes in small white follicles (SWF), large white follicles (LWF), F3, F1, and ovary at week 75 was lower than that in the hens at week 35 (P < 0.05). The mRNA expression in small yellow follicle (SYF) was significantly higher than that at week 35 (P < 0.05), while the mRNA expression of ULK1 in SWF, LWF, F3, F1, and ovary at week 75 was higher than that of hens at week 35 (P＜0.01), and SYF was lower (P < 0.05). Treatment of chicken granulosa cells with the mTOR agonist MHY1485 significantly enhanced granulocyte proliferation (P < 0.01) and inhibited apoptosis (P < 0.01) and significantly increased avTOR, S6K, 4E-BP1, and PKC gene expression (P < 0.01). The protein expression levels of mTOR, S6K, p-mTOR, and p-S6K were consistent with mRNA expression levels. The mTOR activity is age-specific, and a compensatory enhancement of the mTOR signaling cascade can regulate ovarian follicular development in aged laying hens.

Melatonin regulates chicken granulosa cell proliferation and apoptosis by activating the mTOR signaling pathway via its receptors.

Melatonin is a key regulator of follicle granular cell maturation and ovulation. The mammalian target of rapamycin (mTOR) pathway plays an important role in cell growth regulation. Therefore, our aim was to investigate whether the mTOR signaling pathway is involved in the regulation of melatonin-mediated proliferation and apoptotic mechanisms in granulosa cells. Chicken follicle granular cells were cultured with melatonin (0, 2, 20, or 200 µmol/L) for 48 h. The results showed that melatonin treatment enhanced proliferation and suppressed apoptosis in granular cells at 20 µmol/L and 200 µmol/L (P < 0.05) by upregulation of cyclin D1 (P < 0.01) and Bcl-2 (P < 0.01) and downregulation of P21, caspase-3, Beclin1, and LC3-II (P < 0.01). The effects resulted in the activation of the mTOR signaling pathway by increasing the expression of avTOR, PKC, 4E-BP1, S6K (P < 0.05), p-mTOR, and p-S6K. We added an mTOR activator and inhibitor to the cells and identified the optimal dose (10 µmol/L MHY1485 and 100 nmol/L rapamycin) for subsequent experiments. The combination of 20 µmol/L melatonin and 10 µmol/L MHY1485 significantly enhanced granulosa cell proliferation (P < 0.05), while 100 nmol/L rapamycin significantly inhibited proliferation and enhanced apoptosis (P < 0.05), but this action was reversed in the 20-µmol/L melatonin and 100-nmol/L rapamycin cotreatment groups (P < 0.05). This was confirmed by mRNA and protein expression that was associated with proliferation, apoptosis, and autophagy (P < 0.05). The combination of 20 µmol/L melatonin and 10 µmol/L MHY1485 also activated the mTOR pathway upstream genes PI3K, AKT1, and AKT2 and downstream genes PKC, 4E-BP1, and S6K (P < 0.05), as well as protein expression of p-mTOR and p-S6K. Rapamycin significantly inhibited the mTOR pathway-related genes mRNA levels (P < 0.05). In addition, activation of the mTOR pathway increased melatonin receptor mRNA levels (P < 0.05). In conclusion, these findings demonstrate that melatonin regulates chicken granulosa cell proliferation and apoptosis by activating the mTOR signaling pathway via its receptor.

Melatonin regulates the ovarian function and enhances follicle growth in aging laying hens via activating the mammalian target of rapamycin pathway.

The signal pathway of target of rapamycin (TOR) plays an important role in regulating cell growth and proliferation, follicular development, and ovulation. Melatonin (N-acetyl-5-methoxytryptamine) (MT) is involved in the regulation of many physiological functions in animals. Recent studies have shown that MT affects the number and the degree of maturation of follicles in the ovary, but there are few studies concerning its mechanism. Therefore, the aim of this study was to investigate the mechanism of TOR signal pathway in the regulation of ovarian function by MT in aging laying hens. In the present study, a total of 60 hens (70-week-old) were randomly divided into 2 groups: control group and melatonin group (M). Melatonin was administered intraperitoneally at a dose of 20 mg/kg/D for 28 D in the M group. The results showed that MT significantly increased the levels of the antioxidant enzymes superoxide dismutase and total antioxidant capacity (P < 0.01) as well as levels of immunoglobulin (IgA, IgG, and IgM) (P < 0.05) and the reproductive hormones estradiol and luteinizing hormone (P < 0.01) in the plasma and also increased the numbers of middle white follicles and small white follicles (P < 0.05) and decreased the level of reactive oxygen species in plasma (P < 0.01) in laying hens. There were higher expression levels in MT receptor A (P < 0.05), melatonin receptor B (P < 0.01), and tuberous sclerosis complex 2 (P < 0.01). Activation of TOR, 4E binding protein-l (4E-BP1), and ribosomal protein 6 kinase (P < 0.01) was found in the M. The levels of mTOR and p-mTOR protein were increased in the M (P < 0.05). The mTORC1-dependent 4E-BP1 and p-4E-BP1 were increased in the M (P < 0.05). This study indicated that MT may enhance follicle growth by increasing levels of antioxidant enzymes and reproductive hormones and by activating the mTOR and downstream components in aging laying hens.

Identification of a Goat Intersexuality-Associated Novel Variant Through Genome-Wide Resequencing and Hi-C.

Background: Polled intersex syndrome (PIS) leads to reproductive disorders in goats and exerts a heavy influence on goat breeding. Since 2001, the core variant of an 11.7 kb deletion at ~129 Mb on chromosome 1 (CHI1) has been widely used as a genetic diagnostic criterion. In 2020, a ~0.48 Mb insertion within the PIS deletion was identified by sequencing in XX intersex goats. However, the suitability of this variation for the diagnosis of intersex goats worldwide and its further molecular genetic mechanism need to be clarified. Results: The whole-genome selective sweep of intersex goats from China was performed with whole-genome next-generation sequencing technology for large sample populations and a case-control study on interbreeds. A series of candidate genes related to the goat intersexuality phenotype were found. We further confirmed that a ~0.48 Mb duplicated fragment (including ERG and KCNJ15) downstream of the ~20 Mb PIS region was reversely inserted into the PIS locus in intersex Chinese goats and was consistent with that in European Saanen and Valais black-necked goats. High-throughput chromosome conformation capture (Hi-C) technology was then used to compare the 3D structures of the PIS variant neighborhood in CHI1 between intersex and non-intersex goats. A newly found structure was validated as an intrachromosomal rearrangement. This inserted duplication changed the original spatial structure of goat CHI1 and caused the appearance of several specific loop structures in the adjacent ~20 kb downstream region of FOXL2. Conclusions: Results suggested that the novel complex PIS variant genome was sufficient as a broad-spectrum clinical diagnostic marker of XX intersexuality in goats from Europe and China. A series of private dense loop structures caused by segment insertion into the PIS deletion might affect the expression of FOXL2 or other neighboring novel candidate genes. However, these structures require further in-depth molecular biological experimental verification. In general, this study provided new insights for future research on the molecular genetic mechanism underlying female-to-male sex reversal in goats.

Study of measurement methods on phenotype of translucent eggs.

Scoring is a common method to evaluate eggshell translucency, and it mainly depends on the area and the density of translucent spots in eggshells. However, the lack of common scoring criteria and the difficulty of quantitatively measuring spots in eggshells impede effective comparisons between research papers and greatly hinder the progress of research on translucent eggshell. To make measurement of translucent eggshells more objective, we optimized the scoring method and compared it with 2 new methods: grayscale recognition and the colorimeter method. Briefly, a total of 354 eggs from 600, 395-day-old dwarf brown laying hens were collected and classified into 4 score groups according to their degree of translucency. This subjective process was repeated 5 times. Then, we captured the profile side of each egg using a camera and measured spot characteristics using grayscale recognition, which involved measuring the quantity of spots (QS), diameter of each spot (DS), average area of each spot (AAES), sum of spot areas (SUSA), sum of shell area (SUSHA), and ratio of SUSA to SUSHA (RSS) on the eggshell. Furthermore, the L, A, and B values of each egg at the sharp, middle, and blunt ends were separately measured using a colorimeter. As a result, average values of 31.31, 29.78, 29.81, and 9.08% of all eggs were divided into score levels 1, 2, 3, and 4 (from opaque to translucent), which correspond with RSS values of 1.34, 3.23, 6.21, and 11.89%, respectively. By grayscale recognition, QS, DS, AAES, SUSA, SUSHA, and RSS all increased along with increased translucency scores (P < 0.05). Using scoring, an egg with a specific RSS value was more easily assigned to a specific score level (50%) or adjacent score levels (50%). The L, A, and B values of eggshells in score level 1 were significantly different from those of eggshells in levels 3 or 4; however, there were no significant differences between any adjacent score levels. In summary, the present study explored objective reference metrics to measure eggshell translucency.

Genetic variation of major histocompatibility complex BLB2 gene exon 2 in Hebei domestic chicken.

Genetic variation of MHC BLB2 gene exon 2 in Hebei domestic chicken was investigated, after PCR and sequencing of a 374bp fragment (containing entire exon 2 (270bp) of BLB2 gene) in 76 individuals. The results showed that along this fragment, there were 69 variable sites, of which 18 were novel variations, and 82 estimated haplotypes with the diversity of 0.960. In Hebei domestic chicken, the nucleotide diversity (π), the average number of nucleotide differences (k), the average number of nucleotide diversity of synonymous substitution (π(s)) and non-synonymous substitution (π(a)) in BLB2 gene exon 2 were 0.098, 24.688, 0.075, and 0.106, respectively; nine non-synonymous substitutions was exclusively found in the peptide-binding sites (PBS) region of BLB2 gene exon 2, inferring that these unique substitutions might be helpful to resist some special bacteria and pathogens. The higher genetic diversity of MHC BLB2 gene exon 2 in Hebei domestic chicken might be consistent with its more robust disease resistance.

Sequence analysis of the lactoferrin gene and variation of g.7605C→T in 10 Chinese indigenous goat breeds.

Much attention has been focused on the study of lactoferrin at the protein or nucleotide level in mice, humans, and cattle, but little is known about it in goats. The goat LF gene from 5' UTR to exon 17 was amplified, and the variation of g.7605C→T in 10 Chinese indigenous goat breeds was analyzed. Among the three ruminant species (cattle, sheep, and goats), the intron-exon distribution pattern was similar, and all the exons had the same length, but the length of introns varied greatly due to insertions or deletions. The frequency of allele T at g.7605C→T (50.12%) was a little higher than that of allele C (49.88%), and the genotype distribution differed greatly between goat populations. The g.7605C→T site showed higher genetic diversity in goat populations. The genetic differentiation was 0.0783, and gene flow was 2.9433 among the 10 Chinese indigenous goat populations.

Characterization and SNP identification of part of the goat melanophilin gene.

The melanophilin (MLPH) gene has been characterized as the candidate gene for dilute coat color in some species, but little is known about it in the goat. In this study, part of the genomic DNA sequence (19,289 bp) containing the whole coding region of the MLPH gene from goat, as well as from sheep, was determined. We found 16 exons and 15 introns; the coding region was 1767 bp distributed in 15 exons (2-16). In sheep, the length of part of the genomic DNA sequence was 16,988 bp, with 16 exons and 15 introns, and the coding region was 1833 bp, distributed in 15 exons (2-16). Dozens of SNPs as well as some noticeable motifs in the goat MLPH gene were found during the process of sequencing and polymorphism screening. Based on the SSR Tool, three simple sequence repeat motifs were detected in the goat and sheep DNA sequences. Compared with cattle, we found insertions of 4 amino acids in goats and 26 amino acids in sheep.

Variation of 423G>T in the Agouti gene exon 4 in indigenous chinese goat breeds.

The Agouti gene plays an important role in pigment synthesis in domestic animals. A transversion of 423G>T recognized by BanII was found after a fragment (178 bp) of the goat Agouti gene exon 4 was amplified and sequenced. To investigate its genetic effect and diversity, 677 individuals from 12 indigenous Chinese goat breeds and one imported goat breed from South Africa (Boer goat) were analyzed by PCR-RFLP. Two alleles, T and G, and three genotypes, TT, TG, and GG, were detected. Allele T had a higher frequency in most goat breeds and, combined with the coat color phenotype, is believed to be responsible for the black phenotype or to be linked with the causative site in the goat. The results also indicate that the 423G>T transversion showed lower genetic diversity in goat breeds with black coat color in China. Genetic differentiation among the 13 goat populations was 0.2023. The clustering of populations based on the 423G>T site was basically consistent with the variation of coat color.

[Methylation of H19 gene in ES mice and embryonic stem cells].

To investigate the relationship between the methylation status of imprinted gene H19 and the development of mice derived completely from Embryonic stem cells (ES) by tetraploid embryo complementation. The methylation status of two loci at 5'UTR region in imprinted gene H19 in normal adult control mice, 22 adult ES mice, 8 newborn dead ES mice and embryonic stem (ES) cells with different passage number were detected by using of methylation-sensitive restriction endonuclease-PCR technique. The results indicated that the methylation status of the imprinted gene H19 in adult ES mice were identical to that of adult control mice. However, some significant differences in the methylation status of the imprinted gene H19 were found among newborn dead ES mice, adult ES mice and normal adult control mice. Furthermore, the methylation status of the imprinted gene H19 in ES cells were probably different from that of adult ES mice and normal adult control mice.

Bioinformatics analysis of lactoferrin gene for several species.

Much attention has been focused on the study of lactoferrin due to its function in antibacterial, antiviral, antifungal, anti-inflammatory, anti-oxidant, and immunomodulatory activities. A total of 60 lactoferrin (LF) gene sequences with the complete coding regions (CDS) and corresponding amino acids belonging to 11 species were analyzed, and the differentiation within and among the species was also studied. The results showed that most of the species have the stop codon TAA, with the variation of TGA for Mus musculus. The length of the LF gene with the complete CDS varies greatly, from 2,055 to 2,190 bp, due to deletion, insertion, and stop codon mutation resulting in elongation. Observed genetic diversity was higher among species than within species, and Sus scrofa had more polymorphisms than any other species. Novel amino acid variation sites were detected within several species (8 in Homo sapiens, 6 in Mus musculus, 6 in Capra hircus, 10 in Bos taurus, and 20 in Sus scrofa), which might be used to illustrate the functional variation. Differentiation of the LF gene was obvious among species, and the clustering result was consistent with the taxonomy in the National Center for Biotechnology Information.

Passage number affects the pluripotency of mouse embryonic stem cells as judged by tetraploid embryo aggregation.

The aim of this study was to determine whether the number of passages affected the developmental pluripotency of embryonic stem (ES) cells as measured by the attainment of adult fertile mice derived from embryonic stem (ES) cell/tetraploid embryo complementation. Thirty-six newborns were produced by the aggregation of tetraploid embryos and hybrid ES cells after various numbers of passages. These newborns were entirely derived from ES cells as judged by microsatellite DNA, coat-color phenotype, and germline transmission. Although 15 survived to adulthood, 17 died of respiratory failure, and four were eaten by their foster mother. From the 15 mice that reached adulthood and that could reproduce, none arose from ES cells at passage level 15 or more. All 15 arose from cells at passages 3-11. Our results demonstrate that the number of passages affects the developmental pluripotency of ES cells.

Evolution and differentiation of MSHR gene in different species.

Coat color offers some prospects for evolutionary studies due to its large amount of presumably adaptive coat color variation and conserved genetic mechanisms of generating different coat colors in different species. Melanocyte-stimulating hormone receptor (MSHR) gene is responsible for intraspecific and interspecific color variation in mammals and birds. A total number of 206 MSHR gene sequences belonging to 84 species, 58 genera, and 20 families were analyzed to investigate its evolution and differentiation in different species. Most of the species have 954 bp and stop codon TGA. Species in Callithrix and Callimico have a stop codon mutation from TGA to TGG and elongate 81 bp with TAG as stop codon. Species in Phasianidae, Fringillidae, and Lemuridae also use TAG as stop codon. The Sus scrofa had an insertion of AACCAGACC encoding Asn-Gln-Thr from 85 to 93 bp. In Bovidae, a brown strain of cow with 966 bp due to the 12-bp duplication of GGCATTGCCCGG from 670 to 681 bp encoding for Gly-Ile-Ala-Arg was found. Teiidae has the smallest number of total mutations (6), silent mutations (3), nonsynonymous mutations (3), average number of nucleotide differences (1.519), synonymous nucleotide diversity (pi(s) = 0.0030), and nonsynonymous nucleotide diversity (pi(a) = 0.0029), and Hominidae, Lemuridae, Canidae, and Teiidae have higher ratio of pi(a)/pi(s) (0.537-0.973). The reconstructed phylogenetic tree of MSHR gene of families is basically consistent with the taxonomy of National Center for Biotechnology Information.

Study on tandem repeat sequence variation in sheep mtDNA D-loop region.

The 75-nt-long tandem repeat sequence in the control region of mtDNA of 77 individuals, of which 69 were from different indigenous sheep breeds in China and 8 were from imported breeds, was sequenced and analyzed to investigate the origin and differentiation of Chinese indigenous sheep breeds and also the genetic diversities and relationships among them. A total of 28 variable sites were detected within 309 repeated sequences, among which 7 sites were singleton variable sites with two variants, 1 site was a singleton variable site with three variants, and 20 sites were parsimony informative sites with two variants. A total of 63 haplotypes were sorted from 28 polymorphic sites, among which two main and basic haplotypes, namely, Hap 1 and Hap 3 were present at a much higher proportion, at 12.94% and 30.42%, respectively. It could be inferred that Chinese indigenous sheep breeds originated from two maternal ancestors because of the maternal inheritance characteristics of the mtDNA. Altay sheep and Kazakstan sheep are closely related and do not differentiate significantly. Mongolian sheep and Ujumuqin sheep also share a close relationship. Tibetan sheep, Mongolian sheep, and Ujumuqin sheep have lower genetic diversity than Altay sheep and Kazakstan sheep.

SNP identification and analysis in part of intron 2 of goat MSTN gene and variation within and among species.

Part of intron 2 of the myostatin (MSTN) gene of 140 goats from 24 populations and 38 sheep from 8 breeds were sequenced, and similar sequences of different species from Gene bank were also obtained to study MSTN diversity within and among species. The results indicated that there were seven polymorphic sites in the sequenced region of goat, which have not been separated by recombination (or recurrent mutation), presented complete linkage disequilibrium, and could be sorted into three haplotypes. There was no polymorphic site in the sequenced region of sheep. The haplotype diversity, nucleotide diversity, and average number of single nucleotide polymorphism (SNP) differences of goats from the South group are higher than those of North group, and the corresponding value of the Foreign group is also higher than that of Chinese. The genetic differentiation (0.7558) between the Foreign and Chinese group is significant. There are two main haplotypes of the MSTN intron 2 in the goat, which may represent two ancestral types, in support of the theory that domestic goats in the world mainly originated from two ancestors based on morphology, history, archaeology, and molecular markers. The sequence differences of the MSTN intron 2 among species are greater than those within species.