Whole-genome resequencing of Hu sheep identifies candidate genes associated with agronomic traits.

The phenotypic diversity resulting from artificial or natural selection of sheep has made a significant contribution to human civilization. Hu sheep are a local sheep breed unique to China with high reproductive rates and rapid growth. Genome selection signatures have been widely used to investigate the genetic mechanisms underlying phenotypic variation in livestock. Here, we conduct whole-genome sequencing of 207 Hu sheep and compare them with the wild ancestors of domestic sheep (Asiatic mouflon) to investigate the genetic characteristics and selection signatures of Hu sheep. Based on six signatures of selection approaches, we detect genomic regions containing genes related to reproduction (BMPR1B, BMP2, PGFS, CYP19, CAMK4, GGT5, and GNAQ), vision (ALDH1A2, SAG, and PDE6B), nervous system (NAV1), and immune response (GPR35, SH2B2, PIK3R3, and HRAS). Association analysis with a population of 1299 Hu sheep reveal those missense mutations in the GPR35 (GPR35 g.952651 A>G; GPR35 g.952496 C>T) and NAV1 (NAV1 g.84216190 C>T; NAV1 g.84227412 G>A) genes are significantly associated (P < 0.05) with immune and growth traits in Hu sheep, respectively. This research offers unique insights into the selection characteristics of Hu sheep and facilitates further genetic improvement and molecular investigations.

Relationship between sheep feces scores and gastrointestinal microorganisms and their effects on growth traits and blood indicators.

Fecal scores are crucial for assessing the digestive and gastrointestinal status of animals. The Bristol fecal scoring system is a commonly used method for the subjective evaluation of host feces, there is limited research on fecal scoring standards for fattening Hu sheep. In this study, Hu sheep were collected for rumen, rectum, and colon contents for 16S rDNA sequencing. 514 Hu sheep feces were scored based on the Bristol fecal scoring system, and production performance at each stage was measured. Finally, we developed the scoring standard of the manure of Hu sheep in the fattening period (a total of five grades). The result shows that moisture content significantly increased with higher grades (p < 0.05). We analyzed the relationship between fecal scores and production traits, blood indices, muscle nutrients, and digestive tract microorganisms. The growth traits (body weight, body height, body length, average daily gain (ADG), and average daily feed intake (ADFI) during 80-180 days), body composition traits of the F3 group, and the carcass traits were found to be significantly higher (p < 0.05) than those of the F1 and F2 groups. There was no significant difference in gastrointestinal microflora diversity among all groups (p > 0.05). Significant differences were observed in Aspartate aminotransferase, Glucose, Total bilirubin, and Red Blood Cell Count between groups (p < 0.05). The mutton moisture content in group F4 was significantly higher than in the other groups, and the protein content was also the lowest (p < 0.05). The results of the correlation analysis demonstrated that Actinobacteria, Peptostreptococcaceae, Acidaminococcales, Gammaproteobacteria, and Proteobacteria were the significant bacteria affecting fecal scores. In addition, Muribaculaceae and Oscillospiraceae were identified as the noteworthy flora affecting growth performance and immunity. This study highlights the differences in production traits and blood indicators between fecal assessment groups and the complex relationship between intestinal microbiota and fecal characteristics in Hu sheep, suggesting potential impacts on animal performance and health, which suggest strategies for improved management.

Polymorphism in IGFALS gene and its association with scrotal circumference in Hu lambs.

Scrotal circumference is an important reproductive index of breeding rams, which has a high genetic correlation with ejaculation volume and semen quality. In this study, the scrotal circumference of 1353 male Hu sheep at different stages of development was measured and descriptive statistical analysis was performed. The results showed that the coefficient of variation of scrotal circumference at each stage was greater than 10%, and its heritability were moderately to high, ranging from 0.318 to 0.719. We used PCR amplification and Sanger sequencing to scan the polymorphisms of the IGFALS gene, and performed association analysis with the circumference of the scrotum at different stages. We identified a synonymous mutation g.918 G > C in exon 1 of the IGFALS gene, and this mutation was significantly associated with scrotal circumference at 100, 120, 140, 160 and 180 days (p < 0.05). Therefore, IGFALS gene polymorphism can be used as a molecular marker affecting scrotal circumference of Hu sheep, which can provide a reference for future molecular marker-assisted selection of scrotal circumference in sheep.

Polymorphisms of PLIN1 and MOGAT1 genes and their association with feed efficiency in Hu sheep.

Feed cost accounts for a high proportion of sheep production, and improving sheep's utilization of feed will reduce production costs and improve economic benefits. The purpose of this study was to investigate the expression characteristics of PLIN1 and MOGAT1 genes and the relationship between their polymorphisms and feed efficiency traits in Hu sheep, and to find molecular Genetic marker that can be used in breeding. The expression levels of PLIN1 and MOGAT1 genes in various tissues were determined using quantitative real-time PCR (qRT-PCR). The results showed that PLIN1 and MOGAT1 genes were widely expressed in heart, liver, spleen, lungs, kidneys, rumen, duodenum, muscle, lymph, and tail fat. The PLIN1 gene had the highest expression level in in the tail fat compared to the other nine tissues. The expression levels of MOGAT1 gene in liver, tail fat, lung and heart was significantly higher than in kidney, muscle and lymph. The expression level of MOGAT1 was lowest in muscle compared to the other tissues (heart, liver, spleen, lung, rumen and tail fat). We recorded the body weight (BW80 and BW180) and feed intake (FI) information of 985 male Hu sheep at 80 and 180 days of age, and calculated the daily average feed intake (ADFI), average daily gain (ADG), and feed conversion rate (FCR) from 80 to 180 days of age. Two intronic mutations, g.18517910 A > G and g.224856118 G > C, were identified in PLIN1 and MOGAT1 genes by PCR amplification and Sanger sequencing. MassARRAY ® SNP detection technology was used to genotype the DNA of 985 Hu sheep and analyze its association with feed efficiency traits. The results showed that the SNP g.18517910 A > G was significantly associated with BW80, BW180, FI, ADFI and FCR (P < 0.05), while SNP g.2248561118 G > C was significantly associated with FCR (P < 0.05). Meanwhile, significant differences were also observed in different combinations of genotypes (P < 0.05). Therefore, these two polymorphic loci can serve as candidate molecular markers for improving feed utilization efficiency in Hu sheep.

Analysis of liver miRNA in Hu sheep with different residual feed intake.

Feed efficiency (FE), an important economic trait in sheep production, is indirectly assessed by residual feed intake (RFI). However, RFI in sheep is varied, and the molecular processes that regulate RFI are unclear. It is thus vital to investigate the molecular mechanism of RFI to developing a feed-efficient sheep. The miRNA-sequencing (RNA-Seq) was utilized to investigate miRNAs in liver tissue of 6 out of 137 sheep with extreme RFI phenotypic values. In these animals, as a typical metric of FE, RFI was used to distinguish differentially expressed miRNAs (DE_miRNAs) between animals with high (n = 3) and low (n = 3) phenotypic values. A total of 247 miRNAs were discovered in sheep, with four differentially expressed miRNAs (DE_miRNAs) detected. Among these DE_miRNAs, three were found to be upregulated and one was downregulated in animals with low residual feed intake (Low_RFI) compared to those with high residual feed intake (High_RFI). The target genes of DE_miRNAs were primarily associated with metabolic processes and biosynthetic process regulation. Furthermore, they were also considerably enriched in the FE related to glycolysis, protein synthesis and degradation, and amino acid biosynthesis pathways. Six genes were identified by co-expression analysis of DE_miRNAs target with DE_mRNAs. These results provide a theoretical basis for us to understand the sheep liver miRNAs in RFI molecular regulation.

Relationship between hindgut microbes and feed conversion ratio in Hu sheep and microbial longitudinal development.

Feed efficiency is an important indicator in the sheep production process, which plays an important role in improving economic benefits and strengthening energy conservation and emission reduction. Compared with the rumen, the fermentation of the hindgut microorganisms can also provide part of the energy for the host, and the composition of the hindgut microorganisms will affect the feed efficiency. Therefore, we hope to find new ways to regulate sheep feed efficiency by studying the sheep gut microbes. In this study, male Hu sheep with the same birth date were raised under the same conditions until 180 d old. The sheep were divided into high and low groups according to the feed conversion ratio (FCR) at 80 to 180 d old, and the differences in rectal microorganisms between the two groups were compared. The permutational multivariate analysis (PERMANOVA) test showed that there were differences in microorganisms between the two groups (P < 0.05). Combined with linear fitting analysis, a total of six biomarkers were identified, including Ruminobacter, Eubacterium_xylanophilum_group, Romboutsia, etc. Functional enrichment analysis showed that microorganisms may affect FCR through volatile fatty acids synthesis and inflammatory response. At the same time, we conducted a longitudinal analysis of the hindgut microbes, sampling nine-time points throughout the sheep birth to market stages. The microbiota is clearly divided into two parts: before weaning and after weaning, and after weaning microbes are less affected by before weaning microbial composition.

The level of feed efficiency determines the input of sheep production costs and the income of economic benefits. Improving sheep feed efficiency can effectively save energy and reduce emissions. Gut microbes play an important role in the process of feed fermentation. In this study, biomarkers associated with feed efficiency were identified by exploring the relationship between microbes and feed conversion ratio. At the same time, the longitudinal development of microorganisms was explored. It provides a basis for the regulation of intestinal microbes in sheep.

Heritability and recursive influence of host genetics on the rumen microbiota drive body weight variance in male Hu sheep lambs.

BACKGROUND: Heritable rumen microbiota is an important modulator of ruminant growth performance. However, no information exists to date on host genetics-rumen microbiota interactions and their association with phenotype in sheep. To solve this, we curated and analyzed whole-genome resequencing genotypes, 16S rumen-microbiota data, and longitudinal body weight (BW) phenotypes from 1150 sheep. RESULTS: A variance component model indicated significant heritability of rumen microbial community diversity. Genome-wide association studies (GWAS) using microbial features as traits identified 411 loci-taxon significant associations (P < 10-8). We found a heritability of 39% for 180-day-old BW, while also the rumen microbiota likely played a significant role, explaining that 20% of the phenotypic variation. Microbiota-wide association studies (MWAS) and GWAS identified four marker genera (Bonferroni corrected P < 0.05) and five novel genetic variants (P < 10-8) that were significantly associated with BW. Integrative analysis identified the mediating role of marker genera in genotype influencing phenotype and unravelled that the same genetic markers have direct and indirect effects on sheep weight. CONCLUSIONS: This study reveals a reciprocal interplay among host genetic variations, the rumen microbiota and the body weight traits of sheep. The information obtained provide insights into the diverse microbiota characteristics of rumen and may help in designing precision microbiota management strategies for controlling and manipulating sheep rumen microbiota to increase productivity. Video Abstract.

Facet Engineering and Pore Design Boost Dynamic Fe Exchange in Oxygen Evolution Catalysis to Break the Activity-Stability Trade-Off.

The oxygen evolution reaction (OER) plays a vital role in renewable energy technologies, including in fuel cells, metal-air batteries, and water splitting; however, the currently available catalysts still suffer from unsatisfactory performance due to the sluggish OER kinetics. Herein, we developed a new catalyst with high efficiency in which the dynamic exchange mechanism of active Fe sites in the OER was regulated by crystal plane engineering and pore structure design. High-density nanoholes were created on cobalt hydroxide as the catalyst host, and then Fe species were filled inside the nanoholes. During the OER, the dynamic Fe was selectively and strongly adsorbed by the (101̅0) sites on the nanohole walls rather than the (0001) basal plane, and at the same time the space-confining effect of the nanohole slowed down the Fe diffusion from catalyst to electrolyte. As a result, a local high-flux Fe dynamic equilibrium inside the nanoholes for OER was achieved, as demonstrated by the Fe57 isotope labeled mass spectrometry, thereby delivering a high OER activity. The catalyst showed a remarkably low overpotential of 228 mV at a current density of 10 mA cm-2, which is among the best cobalt-based catalysts reported so far. This special protection strategy for Fe also greatly improved the catalytic stability, reducing the Fe leaching amount by 2 orders of magnitude compared with the pure Fe hydroxide catalyst and thus delivering a long-term stability of 130 h. An assembled Zn-air battery was stably cycled for 170 h with a low discharge/charge voltage difference of 0.72 V.

Polymorphism and expression level of the FADS3 gene and associated with the growth traits in Hu sheep.

Growth traits are the economically important traits of sheep, and screening for genes related to growth and development is helpful for the genetic improvement of ovine growth traits. The fatty acid desaturase 3 (FADS3) is one of the important genes affecting the synthesis and accumulation of polyunsaturated fatty acids in animals. In this study, the expression levels of the FADS3 gene and polymorphism of the FADS3 gene associated with growth traits in Hu sheep were detected using quantitative real-time PCR (qRT-PCR), Sanger sequencing, and KAspar assay. The result showed that the expression levels of the FADS3 gene were widely expressed in all tissues, and the expression level of FADS3 in the lung was significantly higher than in other tissues (p < .05). Then, the polymorphism locus g. 2918 A > C was detected in intron 2 of the FADS3 gene, and associated analysis showed that the mutation in the FADS3 gene was associated significantly with growth traits (including body weight, body height, body length, and chest circumference, p < .05). Therefore, individuals with AA genotype showed significantly better growth traits than those with CC genotype, and FADS3 gene could be a candidate gene for improving growth traits in Hu sheep.

Expression profiles of the CD274 and PLEKHH2 gene and association of its polymorphism with hematologic parameters in sheep.

CD274 and PLEKHH2 genes have been identified as immune- and multiple diseases-related genes, and have recently garnered significant interest. However, their role in regulating immune functions in sheep remains largely unexplored. In this study, we aimed to investigate the effects of polymorphisms in CD274 and PLEKHH2 on hematologic parameters in 915 sheep. Our results showed that the CD274 and PLEKHH2 genes were most highly expressed in the spleen and tail fat, respectively, as determined by qRT-PCR. We also identified a G to A mutation (g 0.11858 G > A) in the exon 4 region of CD274, and a C to G mutation (g 0.38384 C > G) in the intron 8 region of PLEKH2. Association analysis revealed that CD274 g 0.11858 G > A was significantly associated with RBC, HCT, MCHC, and MCV (P < 0.05), while PLEKHH2 g 0.38384 C > G was significantly associated with HCT, MPV, MCHC, and MCV (P < 0.05). These results suggest that CD274 and PLEKHH2 genes may play a role in regulating blood physiological indicators and could be potential functional candidates for influencing immune traits in sheep breeding programs.

Detection of single nucleotide polymorphism in HTR4 and its relationship with growth traits in sheep.

In this study, a single nucleotide polymorphism of HTR4 (hydroxytryptamine receptor 4) was detected using DNA sequencing and KASPar (Kompetitive Allele-Specific PCR) technique with the aim of analyzing its effect on growth traits in 1102 sheep. A synonymous mutation g.101220 C > T located on the fifth intron of the ovis HTR4 gene was detected, and association analysis showed that this mutation was significantly associated with growth traits in sheep (p ＜.05), with TT genotypes having significantly lower body weight, height, length and chest circumference than TC and CC genotypes. It showed that the polymorphism of this locus was significantly associated with growth traits in sheep. In addition, qRT-PCR results showed that HTR4 was expressed in different tissues of sheep. It is highly expressed in the liver, spleen and duodenum. As important metabolic, immune and digestive absorption organs in animals, the above tissues can regulate the excitability of intestinal smooth muscle by participating in the body metabolism and nutrient metabolism of sheep, so that sheep can show better growth characteristics. In conclusion, the polymorphic locus identified in HTR4 gene can be used as candidate molecular marker in sheep breeding.

Expression of the Ovine Gene and the Relationship Between Its Polymorphism and Feed Efficiency Traits.

In the mutton industry, feed efficiency traits have the greatest influence on the economic benefits of sheep raised in housing conditions. In this study, quantitative real-time PCR (qRT-PCR), Sanger sequencing, and KASPar methods were used to detect the expression levels of the B cell scaffold protein with ankyrin repeats 1 (BANK1) gene and the relationship between its polymorphism and feed efficiency traits in Hu sheep. The qRT-PCR results showed that the BANK1 gene was extensively expressed in 10 tissues and it was expressed at remarkably higher levels in lymph than in other tissues (p < 0.05). Then, the polymorphism locus, g.93888 A > T, was detected in intron 4 of the BANK1 gene and proved to be remarkably associated with feed efficiency traits (p < 0.05). Hence, the BANK1 gene can be used as a candidate gene for improving the feed efficiency of Hu sheep and this locus could be used as a potential molecular marker for breeding high-feed efficiency sheep in future breeding efforts.

Expression and polymorphisms of CD8B gene and its associations with body weight and size traits in sheep.

The growth traits are economically important traits in sheep. Improving growth rates will increase the profitability of producers. The aim of this study was to identify alleles of CD8B (encoding T-cell surface glycoprotein CD8 beta chain) that are aberrantly expressed in different tissues and to assess the effects and associations of its different genotypes on weight and size traits in sheep. Using quantitative real-time reverse transcription PCR arrays, expression profiling of CD8B was performed in various organs and tissues. CD8B was ubiquitously expressed, with very high expression in the lung, spleen, lymph, duodenum, and liver. One intronic mutation (chr3:62,718,030 (Oar_rambouillet_v1.0, same below) G > A) was identified using pooled DNA sequencing. Subsequently, the variants (AA, AG, and GG) were genotyped using the KASPar® PCR single nucleotide polymorphism (SNP) genotyping system. The results of association analysis with body weight and body size traits in 1304 sheep showed that increases in multiple phenotypic traits correlated with the AA genotype (body weight, p < 0.05; body length, p < 0.05). Thus, SNP chr3:62,718,030 G > A is a promising molecular marker for marker-assisted selection in sheep breeding.

Polymorphism of sheep PRKAA2 gene and its association with growth traits.

Small ruminants farming plays an important role in the livelihood of a large part of the population. Herein we aimed to analyze the effects of single nucleotide polymorphisms in PRKAA2 gene on the growth-related traits of Hu sheep and Dorper sheep. The body weight and body type of 1254 sheep were measured at 80, 100, 120, 140, 160 and 180d, and 37620 phenotypic data were collected. RT-qPCR analysis was performed to test PRKAA2 gene expressed in different tissues of sheep, with the highest expression level in spleen, followed by kidney. In the present study, the PRKAA2 gene sequencing revealed one polymorphism located on Chr1 (Oar_rambouillet_v1.0), termed as chr1:32832382 G > A, and were significantly associated with growth traits of sheep (p < 0.05). The body weight, body length, chest circumference, and cannon circumference of individuals with AA genotype were significantly higher than those with the GG and GA genotypes (p < 0.05). Our findings reveal that PRKAA2 gene could be used as a marker-assisted selection to improve the growth-related traits of sheep.

Transcriptome profiling reveals differential gene expression in the rumen of Hu lambs at different developmental stages.

The development of the rumen is a critical physiological challenge in newborn ruminants. However, the molecular mechanism underlying different stages of rumen development in sheep remains poorly understood. Here, RNA sequencing and bioinformatics analysis were performed to compare the transcription profiles of rumen development at 7, 28 and 56 days of birth (D7, D28 and D56). We identified 1246, 2257 and 627 differentially expressed genes (DEGs) between D7 and D28, between D7 and D56, between D28 and D56, respectively. Also, 70 DGEs were co-expressed at these three time points. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated most DEGs mainly related to transporter activity, channel activity and metabolism pathways. Noteworthy, the expression levels of most genes (CA4, CA9, CA12 and CA14) in nitrogen metabolic pathways were negatively correlated with the papilla length and width, but the papilla length and width were positively correlated with the expression of genes (PLA2G3, SLC26A9, SLC34A3) in ion transport pathway, suggesting that these genes may be involved in nitrogen metabolic and ion transport pathway and thus affect rumen development. These results provide new insight into the changes in RNA expression at different time points of rumen development in Hu sheep.

Polymorphism and expression of the HMGA1 gene and association with tail fat deposition in Hu sheep.

Hu sheep is an excellent short fat-tailed breed in China. Fat deposition in Hu sheep tail affects carcass quality and consumes a lot of energy, leading to an increase in feed cost. The objective of this study was to analyze the effects of HMGA1 polymorphism on tail fat weight in Hu sheep. Partial coding and non-coding sequences of HMGA1 were amplified with PCR and single nucleotide polymorphisms (SNP) of HMGA1 in 1163 Hu sheep were detected using DNA sequencing and KASPar technology. RT-qPCR analysis was performed to test HMGA1 expression in different tissues. The results showed that the expression of HMGA1 was higher in the duodenum, liver, spleen, kidney, and lung than in the heart, muscle, rumen, tail fat, and lymph. A mutation, g.5312 C > T, was detected in HMGA1; g.5312 C > T was significantly associated with tail fat weight, relative weight of tail fat (body weight), and relative weight of tail fat (carcass) (p < 0.05). The tail fat weight of the TT genotype was remarkably higher than that of the CC and TC genotypes. Therefore, HMGA1 can be used as a genetic marker for marker-assisted selection of tail fat weight in Hu sheep.

Effect of feed efficiency on growth performance, body composition, and fat deposition in growing Hu lambs.

The present study aimed to investigate the relationship between growth performance, body composition, and fat deposition factors, and feed efficiency in growing lambs. We measured average daily feed intake (ADFI) and body weight (BW) from 653 Hu sheep that were fed a pellet diet. The residual feed intake (RFI) not significantly genetic and phenotypic correlated with the metabolic body weight (MBW) and average daily gain (ADG), but it was significantly genetic and phenotypic correlated with ADFI and the feed conversion ratio (FCR) (p < 0.01). However, the FCR was significantly associated with growth traits (p < 0.01). With the same ADG, body fat deposition was greater in animals with low feed efficiency compared with high feed efficiency. Therefore, excessive fat deposition can affect the feed efficiency of the body, and organ weight and gut-weight have a greater impact on the feed efficiency of lambs. The reticulum stomach and jejunum of lambs with a low RFI were smaller compared with that in the high RFI, indicating that lambs with a low RFI have less intake and a higher absorption rate. Small organs, such as the liver, of lambs with high FE might be associated with low energy expenditure and slow metabolism. This study provides a new perspective to study the biological processes responsible for feed efficiency variation in lambs.

Polymorphisms in the ovine GP5 gene associated with blood physiological indices.

This study aimed to analyze the effects of polymorphisms in GP5 on blood physiological indices of 1065 sheep. The coefficients of variation of the red blood cell count (RBC), hemoglobin concentration (HGB), mean platelet volume (MPV), mean erythrocyte hemoglobin content (MCH), and red blood cell distribution-coefficient of variation (RDW-CV) were greater than 10%, and there was a very significant correlation between the main indices such as RBC, white blood cell, and platelet count (PLT) and most other indices (p < 0.01). qRT-PCR showed that GP5 was expressed in the heart, liver, spleen, lung, kidney, rumen, duodenum, muscle, tail fat, and lymph tissue, with significantly higher expression in the lymph. Subsequently, we detected single nucleotide polymorphisms (SNPs) in GP5 from group, which identified synonymous mutation g.657 T > C in the first exon of GP5. Association analysis showed significant correlations between the SNP and the physiological traits (p < 0.05), in which the RBC, neutrophilic granulocyte (NEUT) and RDW-CV values in sheep with the TC genotype and TT genotype were markedly lower than those in the CC genotype (p < 0.05). Thus, GP5 polymorphisms could be candidate biomarkers to screen blood physiological indices.

Identification of polymorphic loci in OSMR and GHR genes and analysis of their association with growth traits in sheep.

The aim of this study was to analyze the effect of OSMR and GHR genes polymorphisms on growth traits in sheep. The single nucleotide polymorphisms of sheep OSMR and GHR genes were identified by DNA sequencing technology. A total of two intronic mutations g.2443 T > C and g.170196 A > G were identified in OSMR and GHR, respectively. Correlation analysis was carried out between the obtained genotypes and the growth traits of sheep. The results showed that at the OSMR g.2443 T > C locus, the body weight, chest circumference and cannon circumference of the TT genotype sheep were significantly higher than those of the CC genotype sheep (p < .05). At the GHR g.170196 A > G locus, the body weight, body length, chest circumference and cannon circumference of the AA genotype sheep were significantly higher than those of the AG genotype and GG genotype sheep (p < .05). Moreover, the body weight of sheep of combination TTOSMR/AAGHR genotype was significantly higher than that of other combination genotypes (p < .05). Therefore, we believe that the polymorphic sites identified in the OSMR and GHR genes can be used as candidate molecular markers for breeding good traits in sheep.

Identification of SNPs and expression patterns of ALB, AHSG and GC genes and their association with growth traits in Hu sheep.

Growth traits are economically important traits in sheep breeding. This study was conducted to evaluate the polymorphisms of ALB, AHSG and GC genes and their association with growth traits in Hu sheep. We measured and recorded the body weight (BW), body height (BH), body length (BL) and feed conversion ratio (FCR) of 1418 male Hu sheep raised in the same environment from 80 to 180 days of age. The total of four SNPs in the ALB, AHSG and GC genes were identified by direct sequencing technology. The results of association analysis showed that two loci (g.8699 A>T and g.13458 T>C) of ALB gene significantly affect average daily gain (ADG; P < 0.05). The genotypes of SNP g.2454 T>C in AHSG gene were significantly associated with ADG and FCR (P < 0.05). There were significant associations between GC g.19484 A>C and BW, BH and BL (P < 0.05). The results of qRT-PCR showed that ALB, AHSG, and GC genes were extremely significantly higher in H_BW sheep compared with those in the L_BW sheep (P < 0.01). These results revealed that ALB-1 g.8699 A>T, ALB-2 g.13458 T>C, AHSG g.2454 T>C and GC g.19484 A>C loci are potential molecular markers for Hu sheep breeding.