Shuxia Gao

Chinese indigenous rabbit breeds are highly prized for their unique meat flavor, yet the molecular mechanisms underlying breed-specific flavor profiles remain incompletely understood. This study characterized the longissimus dorsi muscle of two indigenous Chinese black rabbit breeds, Laiwu Black (LW) and Minxinan Black (MX), through integrated analysis of volatilomics (HS-SPME-GC-MS), nontargeted metabolomics (LC-MS/MS), and transcriptomics (RNA-seq). LW rabbits displayed significantly increased intramuscular fatty acid content, characterized by elevated levels of de novo lipogenesis markers and polyunsaturated fatty acids (PUFAs), including linoleic acid (C18:2n6). In contrast, MX rabbits exhibited higher concentrations of elongation products such as C22:5n3 and C22:5n6. ROAV analysis identified hexanal, the primary oxidation product of linoleic acid (C18:2n6), as the most discriminative key odorant between breeds. Transcriptomic profiling revealed 2747 differentially expressed genes, with KEGG pathway analysis identifying PPAR signaling, phospholipase D signaling, and cAMP signaling as significantly enriched pathways. This study employed multi-omics integration through O2PLS analysis, Pearson correlation, and KEGG co-enrichment to identify a central molecular discriminator: the PLD–PA–LPAR lipid signaling axis. Key regulatory genes such as PLA2G7, PLD2, and LPAR family members were found to connect glycerophospholipid metabolism with breed-specific fatty acid partitioning. These findings identify a gene–lipid–volatile network in which PPAR signaling-mediated lipogenesis is associated with polyunsaturated fatty acid (PUFA) substrates for hexanal generation, while PLD–PA–LPAR signaling may influence the allocation of fatty acyl-CoA between phospholipid turnover and triacylglycerol storage. Together, these mechanisms are associated with the breed-specific aroma profiles in rabbit meat.

Amino acids are extremely important nutrients in the feed for fur‐bearing animals, and this study was conducted to evaluate the effects of cystine on the development of hair follicles in Rex rabbits. A total of 224 Rex rabbits at the age of 90 days were randomly divided into 4 groups and fed the diets supplemented with 0 (Control), 0.2%, 0.4%, or 0.6% cystine, and the rabbits were fed for 60 days. The hair follicle density on the dorsal skin and the gene expression and protein phosphorylation levels of components of Wnt signalling pathways were determined. In addition, the dermal papilla cells (DPCs) were isolated from the skin of Rex rabbits and cultured with cystine in vitro to determine the gene expression and protein phosphorylation levels of Wnt signalling pathways. The results showed that addition of cystine in the diets could increase the fur quality ( p < 0.05), and the appropriate of cystine in Rex rabbits' diets was 0.2%. In addition, cystine added to the cell culture medium changed the DPCs cycle progression and promoted cell proliferation. Furthermore, cystine could affect the Wnt10b , CTNNB1 , and Dickkopf‐1 gene expression of Wnt signalling pathways in the skin and DPCs of rabbits ( p < 0.05), and decreased the levels of phosphorylated CTNNB1 and GSK‐3β of Wnt signalling pathways in the skin and DPCs of rabbits ( p < 0.05). Dietary cystine supplemental level could promote the fur quality of Rex rabbits, and the appropriate of cystine in Rex rabbit diets was 0.2%. Furthermore, the molecular mechanism of cystine modulates hair follicle development, probably occurs through activation of Wnt signalling pathways, promotes DPCs proliferation, and increases the hair density of Rex rabbits.

The purpose of this experiment was to study the effects of heat stress on the performance and protein metabolism of skeletal muscle in meat rabbits. A total of 160 New Zealand White rabbits aged 80 days with mean initial body weights of 2359 ± 200 g were randomly divided into a control group and a heat stress group. The experiment duration was 20 days. Heat stress treatment reduced the growth performance and slaughter performance of the rabbits (p < 0.05) and increased muscle yellowness (b*, p < 0.05). In addition, heat stress treatment increased the concentrations of leptin, cholesterol, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol in serum (p < 0.05), and decreased the serum total protein and immunoglobulin (IgG, IgM, and IgA) contents of rabbits. Under the criteria fold-change ≥ 1.20 or ≤0.84 and p-value ≤ 0.05, 7 up-regulated proteins and 122 down-regulated proteins were screened. A gene ontology (GO) enrichment analysis of the differentially expressed proteins was performed. The most enriched specific GO terms among the differential proteins were response to stress, extracellular region, and protein binding in the biological process (BP), cellular component (CC), and molecular function (MF) categories, respectively, and the most enriched pathway was the PI3K/Akt signalling pathway. In conclusion, heat stress could reduce the carcass yield of meat rabbits, change the physical characteristics of the skeletal muscle, and influence protein metabolism by changing blood indices, potentially through the PI3K/Akt signalling pathway.

In the present study, we aimed to observed hair follicle development and describe Wnt10b/β-catenin signaling pathways related to hair follicle development in different ages of Rex rabbits. Six Rex rabbits (3 male and 3 female) of 15, 30, 60, 90, 120 and 150 days of age were selected and skin samples were collected for hair follicle development and Wnt/β-catenin signaling pathway genes expresion detection. The results showed that the the values for body weight, coat length, skin thickness, skin area, and skin weight of Rex rabbits were increased significantly with age (p < 0.05). The total hair follicle density, secondary hair follicle density and the ratio of the secondary hair follicle density to the primary hair follicle density in 120 days of Rex rabbits was higher than that in the other ages (p < 0.05), and the major hair follicles were in the growing period at 15 days and 30 days of age, some of them had already entered the degeneration period at 60 days of age, and most of them entered the degeneration period at 90 days of age, the presence of quiescent hair follicles and the enlargement of primary hair follicles were also observed. At 120 and 150 days of age, the back hair follicles entered the growing period, and the secondary hair follicles had obvious differentiation. Furthermore, the expression of the Wnt10b, CTNNB1, adenomatosis polyposis protein (APC), Disheveled 2 (DVL2), glycogen synthase kinase 3β（GSK-3β）, Lymphoid enhancer-binding factor 1 (LEF1), dickkopf-1 (DKK1) and transforming growth factor beta 1 (TGFβ-1) genes in the skin tissue of Rex rabbits at different age was significantly differences (p < 0.05), and the expression of the Wnt10b, CTNNB1, DVL2, GSK-3β, and TGFβ-1 genes at 90 days was higher than that in the other days, the expression of the LEF1 and DKK1 genes at 60 days was higher than that in the other days. As western blotting indicated, the β-catenin protein phosphorylation (P-CTNNB1) levels in the skin tissue of Rex rabbits shows the trend of first increasing, then decreasing and then increasing, 60 days, 120 days and 150 days significantly higher than 15 days, 30 days or 90 days (p < 0.05). With the increasing of ages, the GSK-3β protein phosphorylation (P-GSK-3β) levels in the skin tissue of Rex rabbits were increasing, and maximum at 120 days of age (p < 0.05). These results show that ages could influence on the fur quality and hair follicle traits of Rex rabbits, and Wnt10b/β-catenin signaling pathways is involved in the biological process of periodic hair follicle development in Rex rabbits. Considering the rule of fur growth, the slaughter age of Rex rabbits should not be earlier than 120 days.

This experiment was conducted to study the effects of different skinning seasons on the fur quality and hair follicle development of Rex rabbits. A total of 80,150-day-old Rex rabbits were slaughtered on 15 July 2022 (summer), 15 October 2022 (autumn), 15 January 2023 (winter), and 15 April 2023 (spring) in Shandong Province (10 males and 10 females in each season). The results show that the skin weight, skin area, skin thickness, and hair follicle density of the Rex rabbits (at 150 days of age) were lower in summer than in winter (p < 0.05). Moreover, the coat length was shorter in summer than in spring, autumn, and winter (p < 0.05). The shoulder fat weight, perirenal fat weight, and perigastric fat weight of the Rex rabbits in winter were higher than those in summer (p < 0.05). Furthermore, the leptin levels in serum were higher in winter than in summer in the Rex rabbits (p < 0.05). In terms of serum biochemistry, the glucose levels were higher in autumn and winter than in spring and summer (p < 0.05). The cholesterol, high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL) in summer had higher values than in winter in the Rex rabbits (p < 0.05). In winter, the expression of the Wnt10b, catenin beta 1 (CTNNB1), glycogen synthase kinase 3 beta (GSK3β), insulin like growth factor I (IGF-I), Type I insulin-like growth factor receptor (IGF-IR), and epidermal growth factor (EGF) genes was higher (p < 0.05), and the expression of the dickkopf-1 (DDK1), transforming growth factor beta 1 (TGFβ-1), bone morphogenetic protein 2 (BMP2), and bone morphogenetic protein 4 (BMP4) genes was lower than in summer (p < 0.05). In summer, the heat shock 70 kDa protein (HSP70) expression and CTNNB1 protein phosphorylation levels in skin tissue were higher than in spring, autumn, and winter (p < 0.05). In winter, Wnt10b protein expression was higher (p < 0.05), and GSK-3β protein phosphorylation levels were lower than in spring, autumn, and winter (p < 0.05). These results show that the skinning season can affect the production performance and hair follicle development of Rex rabbits. Compared with other seasons, the quality of skin from rabbits slaughtered in winter is better. Seasons may regulate hair follicle development via the Wnt10b/β-catenin, TGFβ-BMP, IGF1, and EGF signaling pathways in Rex rabbits.

This study was conducted to investigate the effects of different dietary fibre sources on growth performance, gastrointestinal tract development, caecal fermentation and bacterial composition in the caecal contents of rabbits. A total of 120 35‐day‐old weaned Minxinan black rabbits were divided into three groups and fed a diet composed of peanut straw powder (Group A), alfalfa powder (Group B) and soybean straw powder (Group C) as the main fibre source. The final body weight and average daily gain in Group B were higher than those in Group C, and the average daily feed intake and feed conversion ratio in Group A were lower than those in Group C (p < 0.05). The relative weights of the stomach, small intestine and caecum of rabbits in Group C were higher than those in Groups of B and A, and the relative weights of the caecal contents in Group C were lower than those in Groups A or B (p < 0.05). The pH value and propionic acid, butyric acid and valeric acid concentrations in the caecum of Group C were lower than those in the caecum of Groups A or B, and the concentration of acetic acid in the caecum was lower (p < 0.05). The dominant microbes in the caecal contents of Minxinan black rabbits were Firmicutes, Bacteroidetes and Proteobacteria at the phylum level, and the number of species, Chao1 index and ACE index measured was different between the B–C and A–C groups (p < 0.05). Different dietary fibre sources could affect the growth performance, gastrointestinal tract development and intestinal microbiota of rabbits, and the nutritional value of alfalfa powder was better than that of peanut straw and soybean straw.

This experiment was conducted to study the effects of dietary conjugated linoleic acids (CLAs) on the growth performance, fat metabolism, carcase composition and muscle quality of fattening rabbits. A total of 160 Minxinan black rabbits aged 75 days with body weights of 1658.9 ± 188.8 g were randomly divided into 4 groups. They were fed a basic diet supplemented with 0 (control), 0.5%, 1.0%, or 1.5% CLA for 50 days. Dietary CLA reduced the feed intake and serum triglyceride and cholesterol levels. In addition, the crude protein content in rabbit meat was increased, along with the cholesterol and the ether extract levels in the 1.5% depression group. Moreover, the fatty acid composition in rabbit meat was changed, and the content of polyunsaturated fatty acids/monounsaturated fatty acids (PUFAs/MUFAs) increased with the increasing levels of CLA addition. These findings indicate that CLA greatly improved the nutritional value of rabbit meat. From an economic point of view, CLA would normally be included at a concentration of 0.5% in the formulation of feeds for fattening rabbits.

This study was conducted to evaluate the effect of pyridoxine on the development of hair follicles in Rex rabbits and the underlying molecular mechanism. Two hundred 3-month-old Rex rabbits were randomly divided into 5 groups and fed diets supplemented with 0, 5, 10, 20, or 40 mg/kg pyridoxine. The hair follicle density on the dorsal skin and the gene and protein expression levels of components of the phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB or Akt), Wnt, Notch and bone morphogenetic protein (BMP) signalling pathways were measured. In addition, free hair follicles were isolated from Rex rabbits and cultured with pyridoxine in vitro to measure hair shaft growth. Furthermore, dermal papilla cells (DPC) were isolated from the skin of Rex rabbits and cultured with pyridoxine in vitro to measure the gene and protein expression levels of components of the PI3K/Akt, Wnt, Notch and BMP signalling pathways. The results showed that the addition of dietary pyridoxine significantly increased the total follicle density, secondary follicle density, and secondary-to-primary ratio (S/P, P < 0.05), that the growth ratio of hair stems was promoted by pyridoxine in basic culture medium, and that the growth length of tentacle hair follicles cultured in the pyridoxine group was longer than that in the control group (P < 0.05). In addition, pyridoxine changed the DPC cycle progression and promoted cell proliferation, and appropriate concentrations of pyridoxine (10 and 20 μmol/L) significantly inhibited cell apoptosis (P < 0.05). Pyridoxine significantly affected the gene expression of components of the PI3K/Akt, Wnt and Notch signalling pathways in the skin and DPC of Rex rabbits (P < 0.05), increased the levels of phosphorylated catenin beta 1 (CTNNB1) and Akt, and decreased the level of phosphorylated glycogen synthase kinase 3 beta (GSK-3β) (P < 0.05). Therefore, the molecular mechanism by which pyridoxine promotes hair follicle density in Rex rabbits probably occurs through activation of the PI3K/Akt, Wnt and Notch signalling pathways, prolonging hair follicle growth and delaying the onset of telogen.

This study aimed to evaluate the effects of dietary supplementation with taurine on production performance, serum biochemistry, immunoglobulin, antioxidant and hormones of Angora rabbits. A total of 160 8-month-old Angora rabbits with similar body weight were randomly assigned to one of four dietary groups, with 40 animals per group. The dietary groups consisted of the following different taurine supplementation levels: 0 (control), 0.1, 0.2, and 0.3% (air-dry basis). The 73-d feeding trial (from July 31 to October 11, 2016 in China) included a 7-d adjustment period and a 66-d experimental period. The results showed that taurine dietary supplementation had effects on feed consumption, hair follicle density and wool yield of the Angora rabbits (P<0.05), and adding 0.2% taurine could improve the wool yield. Compared with the control group, serum total cholesterol and low-density lipoprotein levels in supplemented groups were decreased (P<0.05). Dietary supplementation with taurine could improve the activity of superoxide dismutase, enhance total antioxidant capacity and reduce the content of malondialdehyde in serum (P<0.05). Besides, the serum level of thyroid (T4) hormone and insulin-like growth factor-1 in experimental groups was higher than that in the control group (P<0.05). In conclusion, taurine dietary supplementation could reduce the lipid metabolism, enhance the antioxidant capacity and hormone level of Angora rabbits, and adding 0.2% taurine could achieve the effect of increasing wool production.

Secondary hair follicles (SHFs) in the Angora rabbit exhibit classic cyclic hair development, but the multiple molecular signals involved in hair cycling are yet to be explored in detail. In the present study, we investigated the expression pattern, methylation and histone H3 acetylation status of Wnt10b, as a molecular signal participating in hair cycling, during the SHF cycle in the Angora rabbit. Expression of Wnt10b at the anagen phase was significantly higher than that at both the telogen and catagen phases, suggesting that Wnt10b might serve as a critical activator during cyclic transition of SHFs. Methylation frequency of the fifth CpG site (CpG5‐175 bp) in CpG islands at the anagen phase was lower than that at both the catagen and telogen phases. The methylation status of the CpG5 site was negatively correlated with Wnt10b expression. This indicated that the methylation of CpG5 might participate in Wnt10b transcriptional suppression in SHFs. Furthermore, histone H3 acetylation status in the regions‐256~−11 bp and 98 ~ 361 bp were significantly lower at both the catagen and telogen phases than at the anagen phase. The histone H3 acetylation level was significantly positively correlated with Wnt10b expression. This confirmed that histone acetylation was likely involved in upregulating Wnt10b transcription in SHFs. Additionally, potential binding to the transcription factors ZF57 and HDBP was predicted within the CpG5 site. In conclusion, our findings reveal the epigenetic mechanism of Wnt10b transcription and provide a new insight into epigenetic regulation during the SHF cycle in the Angora rabbit.