Rabbit meat production and processing in China

Effects of the Welfare Housing Systems Based on Environmental Enrichment on Growth Performance, Meat Quality, and Intestinal Health in Rabbits

In recent years, consumers have shown a growing interest in purchasing welfare-friendly livestock products. Environmental enrichment has emerged as an effective approach to enhancing animal welfare. Based on this, this study aims to investigate the effects of welfare housing systems incorporating environmental enrichment on growth performance, meat quality, and intestinal health in rabbits. Rabbits were assigned into three groups: Cage group (Cage), Pen group (Pen), and Pen + environmental enrichment material group (PE). The Pen group exhibited a lower average daily weight gain and a higher feed conversion ratio. However, the meat color and nutrient content of the leg muscles were improved in both the Pen and PE groups to varying extents. Furthermore, fatty acid β-oxidation in the leg muscles was elevated in the Pen group, resulting in reduced lipid deposition. Additionally, both the Pen and PE groups displayed altered cecal microbiota composition and increased short-chain fatty acids content, contributing to enhanced intestinal health through the activation of G protein-coupled receptors. In conclusion, these findings suggest that the two welfare housing systems can improve meat quality and intestinal health. This study offers a theoretical foundation for welfare-oriented rabbit farming and the production of healthier rabbit meat to meet consumer demands.

Comprehensive transcriptome of muscle development in Sichuan white rabbit

BACKGROUND

The Sichuan white rabbit is a unique domestic breed and is famous for its high meat production. Muscle development is a complicated biological process, but the underlying regulatory mechanisms have not been elucidated. Here, we generated comprehensive transcriptome datasets (i.e., mRNAs, miRNAs and lncRNAs) in three developmental stages of Sichuan white rabbits, and aim to systematically explore the regulatory network in myogenesis.

RESULTS

We generated extensive transcriptome datasets (mRNAs, miRNAs and lncRNAs) revealing the myogenic regulatory network at different time points. Our differential expression analysis identified 2,995 DE genes, 1,211 DE-lncRNAs, and 305 DE-miRNAs with distinct expression patterns across developmental stages. In addition, functional enrichment analysis of DE mRNAs and miRNAs indicates their involvement in muscle growth, development, and regeneration, highlighting biological processes and muscle-specific functions. Interaction analysis between DE-lncRNAs and mRNAs uncovered a complex regulatory network, especially between 21 and 27 days of development. These findings contribute to better understanding of the transcriptomic changes during muscle development and have implications for breeding improvement in Sichuan white rabbits.

CONCLUSIONS

Our study provides a comprehensive overview of the transcriptomic changes during muscle development in Sichuan white rabbits. The identification and functional annotation of DE genes, miRNAs, and lncRNAs provide valuable insights into the molecular mechanisms underlying this process. These findings pave the way for targeted investigations into the role of non-coding RNAs in muscle biology.

Effects of vine pepper oil on the deterioration of texture quality in boiled rabbit meatballs: Inhibition of hydrophobic interactions and formation of covalent aggregates

This study explored the influence of Sichuan characteristic vine pepper oil (VPO) on the quality of boiled rabbit meatballs. Sensory analysis revealed that VPO addition alleviated the strong undesirable odor of the meatballs. However, increasing VPO content significantly reduced the texture quality and water-holding capacity (WHC), particularly when VPO exceeded 3 % (v/w). SEM and BET-specific surface area analysis indicated that higher VPO levels promoted globular aggregate formation on the gel surface, increased the number of large pores, and resulted in uneven pore volume distribution. Elevated VPO content reduced the storage modulus and hindered the gel-strengthening phase, and intermolecular force analysis demonstrated significant inhibition of hydrophobic interactions between protein molecules during heating. SDS-PAGE further showed that increased VPO induced covalent bonding between meat proteins and VPO components, forming excessive macromolecular aggregates that disrupted the integrity of the gel structure, ultimately leading to reduced product texture and WHC.

Genome-wide chromatin accessibility and selective signals of meat rabbits reveal key Cis-regulatory elements and variants during postnatal development of skeletal muscles in rabbits

BACKGROUND

The development of skeletal muscles is intricately modulated by multiple genetic factors and significantly impacts the economic value of meat rabbits. However, our knowledge of epigenetics in rabbit skeletal muscles remains largely unknown.

RESULTS

In this study, we collected leg skeletal muscles of rabbits and performed assays for transposase-accessible chromatin with high throughput sequencing (ATAC-seq) to detect open chromatin across three developmental stages: birth (D1), weaning (D35), and adulthood (D75). A total of 126,959 accessible chromatin regions (ACRs) were identified across samples, and a broad increase and decrease in chromatin accessibility were found from D1 to D35 and D35 to D75, respectively. Integrative analysis of chromatin accessibility and transcriptome data revealed ACRs that were nearly closed at D1 but highly accessible at D35 and D75 were significantly enriched in skeletal muscle development. Cis-regulation analysis further revealed that genes dominated by enhancers mainly play roles in the neuron development of rabbit skeletal muscles. Moreover, the detection of selection signals of meat rabbits and the footprinting analysis of transcription factor at open chromatin revealed that both base transversion (Chr13:12144967 A-> G) and the dynamics of chromatin accessibility at the PRDM1 binding site might regulate ZSWIM5 during the development of skeletal muscles in rabbits.

CONCLUSIONS

Our study provided a category of potential cis-regulatory elements for understanding the development of skeletal muscles at the tissue level and might facilitate potential insights into growth regulation in rabbits.

Global prevalence of lagomorpha coccidiosis from 1951 to 2024: A systematic review and meta-analysis

The global prevalence of coccidia infection in lagomorphs and potential risk factors were investigated through a meta-analysis of 149 studies published between 1951 and 2024. The pooled prevalence of Eimeriidae, Sarcocystidae and Cryptosporidiidae was found to be 66.0 %, 8.0 % and 6.1 %, respectively. Rabbits and hares exhibited the highest prevalence of Eimeriidae at 63.1 % and 71.8 %, while pikas had the highest prevalence of Cryptosporidiidae at 17.1 %. Countries located in the southern hemisphere exhibited the highest prevalence of Cryptosporidiidae (11.4 %). The African Region had the highest prevalence of Eimeriidae (73.3 %) and Sarcocystidae(14.6 %), while the Eastern Mediterranean Region had the highest prevalence of Cryptosporidiidae(13.6 %). Juvenile rabbits exhibited the highest prevalence of Eimeriidae (67.4 %), while senior Rabbit exhibited the highest prevalence of Sarcocystidae(17.1 %) and Cryptosporidiidae(13.1 %). The prevalence of coccidia in intensively farmed lagomorphs showed a slight upward trend over time, nearly reaching statistical significance (R2 = 7.88 %, coefficient = 0.019, P = 0.127). This suggests that the current intensive farming practices may be losing effectiveness in controlling coccidia infections, which is concerning. Among Eimeriidae in lagomorphs, Eimeria coquelinae showed the highest prevalence (68.4 %), while E. magna was most frequently reported. For Sarcocystidae, Besnoitia spp. had the highest prevalence (31.3 %), with Toxoplasma gondii being most frequently reported. Cryptosporidium cuniculus was both the most prevalent and frequently reported Cryptosporidiidae species (6.9 %), suggesting it may be a major Cryptosporidiidae pathogen in lagomorphs. These findings highlight the differences in prevalence of various Eimeriida species among different lagomorpha genera. This diversity underscores the complex relationships between specific parasites and their host species, contributing to a more nuanced understanding of coccidiosis epidemiology in lagomorphs worldwide.

Migration and risk assessment of heavy metals from swine manure in an organic fertilizer - soil - ryegrass - rex rabbit system: Based on field trials

Organic fertilizers were produced through maggot-composting (MC) and natural composting (NC) using swine manure, and the migration, contamination, and health risks of heavy metals (Zn, Cu, Cd, Cr, Pb) were evaluated within a fertilizer - soil - ryegrass - Rex rabbit system. After 70 days of treatment, heavy metals were concentrated by 43.23 % to 100 % in MC and 52.82 % to 90.91 % in NC, higher concentration rate was observed in Cr and Cu in NC. The residual fractions of Zn, Cu, CD, Cr, Pb increased by 0.4 % to 30.2 % in MC, and 3.4 % to 29.7 % in NC. More stable forms of Zn, Cr, and Cu were observed in NC, whereas Pb showed greater stability in MC. Post-fertilization, statistically higher levels of the five elements were obtained in NC treatment. Even their concentrations decreased in the soil, however, high initial background levels caused Cr and Zn to exceed standard thresholds in both treatments. Despite this, the geo-accumulation index (Igeo) and pollution load index (PLI) below 1, did not indicate a pollution risk. Cr levels exceeded feed limits in both roots and leaves, although the low BCF value in roots suggested limited risk. In rabbits fed with 48 % ryegrass, significantly higher levels of Zn and Cu were detected in NC, with elevated Cr levels posed moderate to severe pollution risks in two treatments. Health risk assessments, including non-carcinogenic (HQf) and carcinogenic risks (CRf), revealed Cr was the most cautionary element for both children and adults, even no significant carcinogenic risk exist. These findings provide key insights into mitigating heavy metal contamination from animal waste to rabbit meat.

Improving quality and consumer acceptance of rabbit meat: Prospects and challenges

Rabbit meat is an excellent source of high-quality proteins, essential fatty acids, vitamins, and minerals, which can be further improved through various management, preslaughter, and post-slaughter interventions. Rabbit meat consumption is popular in certain regions of the world. The multidimensional role of rabbits as pet, pest, and laboratory animals, lack of proper knowledge among consumers towards the nutritive value of rabbit meat, animal welfare, and ethical issues, sustainable potential, undeveloped marketing, and processing chain, and price parity with available cheap meat and non-meat alternatives, are some constraints in the rabbit meat production. Increasing awareness of the nutritive value, positive health effects of rabbit meat consumption and production chain, development of processed meat products, and proper animal welfare compliance in rabbit production could improve consumer acceptance. The present manuscript reviewed various factors that affect the meat quality and consumer acceptance of rabbit meat for a more sustainable and viable source for global meat supply.

Transcriptome-wide association studies identify candidate genes for carcass and meat traits in meat rabbits

Meat rabbits are a small herbivorous livestock and have been popularly raised in China for producing high-quality meat. Therefore, it is economically important to genetically improve both carcass performance and meat quality in meat rabbits. However, we still know less about the underlying candidate genes that may determine phenotypic variation on carcass and meat traits of meat rabbits. The main objective of this study was to identify candidate genes whose mRNA expression levels may be significantly involved in regulating carcass and meat traits of meat rabbits based on the transcriptome-wide association studies (TWAS). Five carcass traits of the carcass weight (CW), dressing out percentage (DP), cut weight of hind legs (LW), weight ratio of cut hind legs to carcass (RLW), and weight of visceral and interscapular fat (WF), as well as two meat traits of the drip loss (DL) and cooking loss (CL) were phenotyped in a F1 crossbred population (N = 119) between Zika rabbits and Sichuan White rabbits. The effects of mRNA expression levels of a total of 10,288 genome-wide genes on these seven traits were statistically estimated using the mixed linear model, in which the polygenic background effects were accounted for. Our results revealed two candidate genes (RDH5 and MTARC2) that were statistically significantly associated with LW trait (the adjusted p values <0.05), whereas no gene reached the statistically significant threshold for all the remaining six traits. Because of the relatively small sample size analyzed, we alternatively selected 20 candidate genes with the lowest p values for every trait and subjected them to functional enrichment analyses, which identified three Gene Ontology (GO) terms that were significantly enriched by the candidate genes of CW and RLW traits. In conclusion, this study used TWAS approach to successfully reveal several candidate genes whose mRNA expression levels may be involved in regulating carcass and meat traits in meat rabbits, which are helpful to explore the underlying molecular mechanism in the future studies.

Understanding Consumer Preferences for Attributes of Yak Meat: Implications for Economic Growth and Resource Efficiency in Pastoral Areas

Realizing the market value of grassland resources is of great significance to finding a balance between ecological protection and economic development. As a unique livestock animal that is native to the Qinghai-Xizang Plateau, the yak plays an important role in maintaining ecosystem stability, ensuring the livelihoods of herdsmen, promoting socio-economic development, and preserving ethnic cultural traditions. However, given its small market share, little is known about the factors that drive Chinese consumer preferences for yak meat. This study aimed to investigate consumer preferences for yak meat by means of an online survey involving a sample of 2999 respondents from five cities in China. The best-worst scaling method was employed to measure the relative importance of different attributes of yak meat by using a purchasing scenario. The results indicated that quality-safety certification, freshness, and production sustainability were regarded as the most preferred attributes, whereas animal welfare, brand, and the purchasing channel were found to be the least preferred. In addition, significant heterogeneity was detected in consumer preferences. Consumers were divided into three classes, namely 'Price Sensitive Consumers,' 'Environmentally Friendly Consumers,' and 'Yak Meat Inclined Consumers,' respectively. Our findings might be helpful for policymakers and yak meat producers to develop targeted strategies to facilitate the sale of yak meat and then restore degraded grasslands.

In Vivo Imaging of Rabbit Follicles through Combining Ultrasound Bio-Microscopy and Intravital Window

Continuous ovarian imaging has been proven to be a method for monitoring the development of follicles in vivo. The aim of this study was to evaluate the efficacy of combining ultrasound bio-microscopy (UBM) with an intravital window for follicle imaging in rabbits and to monitor the ovarian dynamic processes. New Zealand White female rabbits (n = 10) received ovarian translocation to a subcutaneous position. The ovarian tissue was sutured onto the abdominal muscles and covered with an intravital window for the continuous monitoring of the follicles using UBM. Results show that physiological changes (red blood cell and white blood cell counts, feed intake, and body weight change) in rabbits induced by surgery returned to normal physiological levels in one week. Furthermore, UBM could provide high-resolution imaging of follicles through the intravital window. Daily monitoring of ovarian dynamic processes for 6 days displayed variabilities in follicle counts and size. Collectively, these results provide a relatively new method to monitor ovarian dynamic processes and to understand the reproductive physiology of female rabbits.

Delineating molecular regulatory network of meat quality of longissimus dorsi indicated by transcriptomic, proteomic, and metabolomics analysis in rabbit

This study aims to investigate the potential regulatory network responsible for the meat quality using multi-omics to help developing better varieties. Slaughter performance and meat quality of Shuxing No.1 rabbit outperformed IRA rabbit according to the tested rabbit parameters. Differentially expressed genes (DEGs) and differentially abundance proteins (DAPs) were involved in meat quality-related pathways, such as PI3K - Akt and MAPK signaling pathways. Only SMTNL1 and PM20D2 shared between DEGs and DAPs. Olfactory-sensitive undecanal, a differentially abundant metabolite (DAM) in volatilomics (vDAMs), correlated with all of the remaining 11 vDAMs, and most of 12 vDAMs were associated with amino acid metabolism. Integration revealed that 829 DEGs/DAPs were associated with 15 DAMs in four KEGG pathways, such as melatonin (a DAM in widely targeted metabolomics) was significantly positively correlated with ALDH and negatively correlated with RAB3D and CAT in the tryptophan metabolism pathway. This study sheds light on the potential mechanisms that contribute to the improved meat quality and flavor. SIGNIFICANCE: Shuxing No.1 rabbit is a new breed of meat rabbit in the Chinese market. In meat marketing, meat quality usually determines the purchase intention of consumers. Determining the biological and molecular mechanisms of meat quality in meat rabbit is essential for developing strategies to improve meat quality. According to the tested rabbit parameters, this study ascertained that the slaughter performance and meat quality of Shuxing No.1 rabbit surpasses that of IRA rabbit. The present study profiled the transcriptome, proteome, widely targeted metabolome, and volatilome of longissimus dorsi from Shuxing No.1 rabbit and IRA rabbit. The study found that meat quality and flavor-related tryptophan metabolism pathway is enriched with many DEGs/DAPs (including ALDH, RAB3D, and CAT), as well as a DAM, melatonin. This study sheds light on the potential mechanisms that contribute to the improved meat quality and flavor.

Social, ethical, environmental, economic and technological aspects of rabbit meat production - A critical review

Rabbit (RM) has become a valuable source of nutrients since the 1970s, helping to transform the European food industry into the largest RM producer in the world. However, the RM industry is experiencing a critical period of ethical imbalance. This trend, described as feed conversion ratio, impacts the environmental and financial performance of RM farms, which could lead to an increase production of industrial waste. In addition, the loss of corporate ethical responsibility and sustainable development by RM-oriented companies has further exacerbated the situation. Our objective was to summarize current trends in the RM industry and markets, highlighting possible strengths and weaknesses. This review shows current approaches in sustainable techniques in RM production processes, ethical issue, environmental and processing responsibility of RM producers, as well as social responsibilities and ethical practices of slaughterhouses and RM producers, sustainable environmental practices of slaughterhouses, technological aspects and safety of RM and social drivers in RM market. The analysis of reviewed literature revealed the potential strategies for sustainable RM production.

Epidemiological characterization and risk assessment of rabbit haemorrhagic disease virus 2 (RHDV2/b/GI.2) in the world

A novel variant of rabbit haemorrhagic disease virus, designated RHDV2/b/GI.2, was first discovered in France in 2010. Subsequently, RHDV2 rapidly spread to Africa, North America, Australia, and Asia. RHDV2 outbreaks have resulted in significant economic losses in the global rabbit industry and disrupted the balance of natural ecosystems. Our study investigated the seasonal characteristics of RHDV2 outbreaks using seasonal indices. RHDV2 is prone to causing significant outbreaks within domestic and wild rabbit populations during the spring season and is more likely to induce outbreaks within wild rabbit populations during late autumn in the Southern Hemisphere. Furthermore, based on outbreak data for domestic and wild rabbits and environmental variables, our study established two MaxEnt models to explore the relationship between RHDV2 outbreaks and the environmental factors and conducted outbreak risk predictions for RHDV2 in global domestic and wild rabbit populations. Both models demonstrated good predictive performance, with AUC values of 0.960 and 0.974, respectively. Road density, isothermality, and population density were identified as important variables in the outbreak of RHDV2 in domestic rabbits, while road density, normalized difference vegetation index, and mean annual solar radiation were considered key variables in the outbreak of RHDV2 in wild rabbits. The environmental factors associated with RHDV2 outbreaks identified in our study and the outbreak risk prediction maps generated in our study will aid in the formulation of appropriate RHDV2 control measures to reduce the risk of morbidity in domestic and wild rabbits.

Integrated analysis reveals the regulatory mechanism of the neddylation inhibitor MLN4924 on the metabolic dysregulation in rabbit granulosa cells

BACKGROUND

Neddylation, an important post-translational modification (PTM) of proteins, plays a crucial role in follicular development. MLN4924 is a small-molecule inhibitor of the neddylation-activating enzyme (NAE) that regulates various biological processes. However, the regulatory mechanisms of neddylation in rabbit ovarian cells have not been emphasized. Here, the transcriptome and metabolome profiles in granulosa cells (GCs) treated with MLN4924 were utilized to identify differentially expressed genes, followed by pathway analysis to precisely define the altered metabolisms.

RESULTS

The results showed that 563 upregulated and 910 downregulated differentially expressed genes (DEGs) were mainly enriched in pathways related to cancer, cell cycle, PI3K-AKT, progesterone-mediated oocyte maturation, and PPAR signaling pathway. Furthermore, we characterized that MLN4924 inhibits PPAR-mediated lipid metabolism, and disrupts the cell cycle by promoting the apoptosis and proliferation of GCs. Importantly, we found the reduction of several metabolites in the MLN4924 treated GCs, including glycerophosphocholine, arachidic acid, and palmitic acid, which was consistent with the deregulation of PPAR signaling pathways. Furthermore, the increased metabolites included 6-Deoxy-6-sulfo-D-glucono-1,5-lactone and N-Acetyl-D-glucosaminyldiphosphodolichol. Combined with transcriptome data analyses, we identified genes that strongly correlate with metabolic dysregulation, particularly those related to glucose and lipid metabolism. Therefore, neddylation inhibition may disrupt the energy metabolism of GCs.

CONCLUSIONS

These results provide a foundation for in-depth research into the role and molecular mechanism of neddylation in ovary development.

Unraveling the Physicochemical Properties and Bacterial Communities in Rabbit Meat during Chilled Storage

The freshness and bacterial communities of fresh and salted rabbit meat during 8 days of refrigerated storage at 4 °C were evaluated. The results showed that the addition of 2% salt significantly changed the color of meat, of which the lightness (L*), redness (a*), and yellowness (b*) were lower than that of fresh meat over time. The pH of all samples increased during storage, and meat with salt addition had lower values in comparison to fresh samples over time. The total volatile base nitrogen (TVB-N) concentration increased rapidly in salt-treated meat but was significantly (p < 0.05) lower than that in meat without salt added before 6 days. Over time, the content of thiobarbituric acid reactive substances (TBARS) showed a progressive trend, but a rapid increase occurred in salted meat. High-throughput sequencing showed that the microflora of each sample had a positive trend in alpha diversity and a negative trend in beta diversity. Bacterial taxonomic analysis indicated that the initial microbial flora for chilled rabbit meat was dominated by Shigaella, Bacteroides, and Lactococcus, and the population of Brochothrix and Psychrobacter increased over time and became the dominant spoilage bacterium. In particular, the addition of salt significantly reduced the abundance of Psychrobacter and Brochothrix. These findings might provide valuable information regarding the quality monitoring of rabbit meat during chilled storage.

Long-read sequencing-based transcriptomic landscape in longissimus dorsi and transcriptome-wide association studies for growth traits of meat rabbits

Rabbits are an attractive meat livestock species that can efficiently convert human-indigestible plant biomass, and have been commonly used in biological and medical researches. Yet, transcriptomic landscape in muscle tissue and association between gene expression level and growth traits have not been specially studied in meat rabbits. In this study Oxford Nanopore Technologies (ONT) long-read sequencing technology was used for comprehensively exploring transcriptomic landscape in Longissimus dorsi for 115 rabbits at 84 days of age, and transcriptome-wide association studies (TWAS) were performed for growth traits, including body weight at 84 days of age and average daily gain during three growth periods. The statistical analysis of TWAS was performed using a mixed linear model, in which polygenic effect was fitted as a random effect according to gene expression level-based relationships. A total of 18,842 genes and 42,010 transcripts were detected, among which 35% of genes and 47% of transcripts were novel in comparison with the reference genome annotation. Furthermore, 45% of genes were widely expressed among more than 90% of individuals. The proportions (±SE) of phenotype variance explained by genome-wide gene expression level ranged from 0.501 ± 0.216 to 0.956 ± 0.209, and the similar results were obtained when explained by transcript expression level. In contrast, neither gene nor transcript was detected by TWAS to be statistically significantly associated with these growth traits. In conclusion, these novel genes and transcripts that have been extensively profiled in a single muscle tissue using long-read sequencing technology will greatly improve our understanding on transcriptional diversity in rabbits. Our results with a relatively small sample size further revealed the important contribution of global gene expression to phenotypic variation on growth performance, but it seemed that no single gene has an outstanding effect; this knowledge is helpful to include intermediate omics data for implementing genetic evaluation of growth traits in meat rabbits.

Effects of different roasting temperatures on rabbit meat protein oxidation and fluorescent carbon nanoparticle formation

This study explores the oxidation of rabbit meat proteins and the physicochemical properties of the resulting fluorescent carbon nanoparticles (CNPs) under various roasting temperatures (180, 210, 240, 270, and 300 °C). The determination of sulfhydryl content, along with the results from UV and fluorescence spectroscopy, indicates that the protein structure undergoes changes during the roasting process, and the degree of oxidation shows an increasing trend with rising roasting temperatures. The CNP solution obtained exhibits a typical blue fluorescence. Moreover, as the roasting temperature increases from 180 °C to 300 °C, the relative content of the three elements in CNPs, namely C, N, and O, increases by 12 %, -3%, and -9 %, respectively. The surface of the obtained rabbit meat CNPs contains hydrophilic and polycyclic groups, such as carbonyl, hydroxyl, and amide bonds. Correlation analysis reveals a significant positive correlation between the degree of protein oxidation and the fluorescence intensities of CNPs.

Seasonal Variations in Production Performance, Health Status, and Gut Microbiota of Meat Rabbit Reared in Semi-Confined Conditions

In this study, we investigated the variations in production performance, health status, and gut microbiota of meat rabbits raised in the semi-confined barn during summer and winter. Compared to summer, rabbits reared in winter possessed significantly higher slaughter weight and carcass weight. Rabbits fed in the summer were more vulnerable to different stressors, which led to increased protein levels of HSP90, IL-1α, IL-1β, IL-2, and concentrations of MDA, but declined GSH and SOD activities. Additionally, significant differences in gut microbial communities were observed. Compared to the winter, rabbits fed in the summer had significantly lower and higher alpha and beta diversity. Both Firmicutes and Verrucomicrobiota were the dominant phyla, and they accounted for greater proportions in the winter than in the summer. At lower microbial taxa levels, several seasonal differentially enriched microbes were identified, such as Akkermansia muciniphila, the Oscillospiraceae NK4A214 group, the Christensenellaceae R-7 group, Alistipes, and Muribaculaceae. Functional capacities linked to microbial proliferation, nutrient metabolism, and environmental adaptive responses exhibited significantly different abundances between summer and winter. Moreover, strong interactions among different indicators were presented. Based on our findings, we not only proposed several potential strategies to ameliorate the undesirable effects of seasonal changes on the productivity and health of meat rabbits but also underscored the directions for future mechanistic studies of adaptation physiology.

New insights in improving sustainability in meat production: opportunities and challenges

Treating livestock as senseless production machines has led to rampant depletion of natural resources, enhanced greenhouse gas emissions, gross animal welfare violations, and other ethical issues. It has essentially instigated constant scrutiny of conventional meat production by various experts and scientists. Sustainably in the meat sector is a big challenge which requires a multifaced and holistic approach. Novel tools like digitalization of the farming system and livestock market, precision livestock farming, application of remote sensing and artificial intelligence to manage production and environmental impact/GHG emission, can help in attaining sustainability in this sector. Further, improving nutrient use efficiency and recycling in feed and animal production through integration with agroecology and industrial ecology, improving individual animal and herd health by ensuring proper biosecurity measures and selective breeding, and welfare by mitigating animal stress during production are also key elements in achieving sustainability in meat production. In addition, sustainability bears a direct relationship with various social dimensions of meat production efficiency such as non-market attributes, balance between demand and consumption, market and policy failures. The present review critically examines the various aspects that significantly impact the efficiency and sustainability of meat production.

Potential and limitations of rabbit meat in maintaining food security in Ukraine

The aim of the present review was to assess whether rabbit meat production can help to improve food security in Ukraine and whether it can make a meaningful contribution to the national economy. Rabbit meat is a nutrient-rich and affordable food with a lower environmental impact than red meat from cattle or sheep. Rabbit meat is considered healthy, as it is lower in fat, cholesterol and sodium than other types of meat, and rich in protein. In addition, rabbit meat proteins can serve as a source of bioactive peptides with the angiotensin converting enzyme (ACE) inhibition properties. The health-promoting properties of rabbit meat and role of associated by-products in providing nutritious and safe food for consumers, and in reducing waste in the meat sector, should be promoted. In Ukraine, rabbit meat products are already recommended as part of a healthy diet for children, pregnant women and the elderly, and the market could be broadened by introducing more rabbit-based products for the whole population. Rabbit production in Ukraine is a promising area of economic activity and with a broader market this segment could increase further and become a significant part of the economy. However, the rabbit farming sector in Ukraine needs comprehensive improvement to address existing issues, including the introduction of sustainable production methods in accordance with European animal welfare and meat quality standards.

Changes in flavor substances during the processing of boneless cold-eating rabbit meat

Cold-eating rabbit is a traditional Chinese delicacy made by the process of pickling and frying. To explore the relationship between the flavor of cold-eating rabbit and the production process, this study investigated the changes of nucleotides, free amino acids, fatty acids, and volatile flavor substances in diced, marinated for 10 min, marinated for 20 min, fried for 5 min, re-fried for 10 min, re-fried for 15 min, re-fried for 20 min, seasoned and fried, and in the finished product, and analyzed the changes of flavor substances in deboned rabbit at different processing stages. Results showed that the content of 5'-inosine monophosphate (IMP) increased significantly (p < .05), indicating that the degradation pathway mainly involved IMP. In total, 17 free amino acids were detected, the contents of which increased significantly (p < .05). In addition, 27 medium- and long-chain fatty acids were detected. The total concentration of free fatty acids decreased in the fresh rabbit meat-marinated 20 min stage (p < .05), then increased in the fried 5 min-fried 20 min stage (p < .05), and finally decreased in the fried with spices-finished stage (p < .05). Seventy-seven volatile flavor substances were detected, and the 15-minute frying stage was key in producing the volatile flavor substances.

Impact of coprophagy prevention on the growth performance, serum biochemistry, and intestinal microbiome of rabbits

BACKGROUND

Coprophagy plays a vital role in maintaining growth and development in many small herbivores. Here, we constructed a coprophagy model by dividing rabbits into three groups, namely, control group (CON), sham-coprophagy prevention group (SCP), and coprophagy prevention group (CP), to explore the effects of coprophagy prevention on growth performance and cecal microecology in rabbits.

RESULTS

Results showed that CP treatment decreased the feed utilization and growth performance of rabbits. Serum total cholesterol and total triglyceride in the CP group were remarkably lower than those in the other two groups. Furthermore, CP treatment destroyed cecum villi and reduced the content of short-chain fatty acids (SCFAs) in cecum contents. Gut microbiota profiling showed significant differences in the phylum and genus composition of cecal microorganisms among the three groups. At the genus level, the abundance of Oscillospira and Ruminococcus decreased significantly in the CP group. Enrichment analysis of metabolic pathways showed a significantly up-regulated differential metabolic pathway (PWY-7315, dTDP-N-acetylthomosamine biosynthesis) in the CP group compared with that in the CON group. Correlation analysis showed that the serum biochemical parameters were positively correlated with the abundance of Oscillospira, Sutterella, and Butyricimonas but negatively correlated with the abundance of Oxalobacte and Desulfovibrio. Meanwhile, the abundance of Butyricimonas and Parabacteroidesde was positively correlated with the concentration of butyric acid in the cecum.

CONCLUSIONS

In summary, coprophagy prevention had negative effects on serum biochemistry and gut microbiota, ultimately decreasing the growth performance of rabbits. The findings provide evidence for further revealing the biological significance of coprophagy in small herbivorous mammals.

On-Farm and Processing Factors Affecting Rabbit Carcass and Meat Quality Attributes

Rabbit meat has high nutritional and dietetic characteristics, but its consumption rate is comparatively lower than other meat types. The nutritional profile of rabbit meat, by comparison with beef, pork, and poultry, is attributed to relatively higher proportions of n-3 fatty acids and low amounts of intramuscular fat, cholesterol, and sodium, indicating its consumption may provide health benefits to consumers. But, the quality attributes of rabbit meat can be originated from different factors such as genetics, environment, diet, rearing system, pre-, peri-, and post-slaughter conditions, and others. Different rabbit breeds and the anatomical location of muscles may also affect the nutritional profile and physicochemical properties of rabbit meat. However, adequate information about the effect of those two factors on rabbit meat is limited. Therefore, cumulative information on nutritional composition and carcass and meat quality attributes of rabbit meat in terms of different breeds and muscle types and associated factors is more important for the production and processing of rabbits. Moreover, some studies reported that rabbit meat proteins exhibited angiotensin-converting enzyme inhibitory characteristics and antioxidant properties. The aim of this review is to elucidate the determinants of rabbit meat quality of different breeds and its influencing factors. In addition, the proven biological activities of rabbit meat are introduced to ensure consumer satisfaction.

The Use of Metabolomics as a Tool to Compare the Regulatory Mechanisms in the Cecum, Ileum, and Jejunum in Healthy Rabbits and with Diarrhea

Simple Summary

The problems caused by antibiotic abuse have swept the world, and the Chinese government has responded to calls for a comprehensive ban on antibiotics. However, not using antibiotics also challenges China’s existing livestock industry. Based on this, we carried out a nontargeted metabolomics analysis of the jejunum, ileum, and cecum of diarrhea rabbits and normal rabbits fed with antibiotic-free diets, respectively, to find out the mechanism of action of each intestinal segment group and between different intestinal segments. The screened differential metabolites were mostly related to intestinal barrier, intestinal inflammation, and autophagy after a KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis. In this paper, we analyzed the metabolic pathways that were significantly different between different intestinal segments and illustrated the mechanism and potential connections of the screened differential metabolites in different intestinal segments in the form of charts.

Abstract

For many years, antibiotics in feed have been an effective and economical means to promote growth and disease resistance in livestock production. However, the rampant abuse of antibiotics has also brought very serious harm to human health and the environment. Therefore, the Chinese government promulgated laws and regulations on 1 July 2020, to prohibit the use of antibiotics in feed. To improve the effect of antibiotic-free feeding on China’s existing rabbit industry, we used the nontargeted metabolomics method to detect the differences between diarrhea rabbits (Dia) and normal rabbits (Con) on an antibiotic-free diet. A total of 1902 different metabolites were identified. A KEGG analysis showed that in the cecum, metabolites were mainly concentrated in bile secretion, antifolate resistance, aldosterone synthesis, and secretion pathways. The ileal metabolites were mainly concentrated in tyrosine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, steroid hormone biosynthesis, alanine, aspartate, and glutamate metabolism. The metabolites in the jejunum were mainly rich in panquinone and other terpenoid compound quinone biosynthesis, AMPK (adenosine 5′-monophosphate (AMP)-activated protein kinase) signal, inositol phosphate metabolism, and pentose phosphate pathway. After a deep excavation of the discovered differential metabolites and metabolic pathways with large differences between groups, it was found that these metabolic pathways mainly involved intestinal inflammation, intestinal barrier, and autophagy. The results showed that panquinone and other terpenoids could increase AMPK activity to promote cell metabolism and autophagy, thus trying to prevent inflammation and alleviate intestinal disease symptoms. In addition, we discussed the possible reasons for the changes in the levels of seven intestinal endogenous metabolites in rabbits in the diarrhea group. The possibility of improving diarrhea by adding amino acids to feed was discussed. In addition, the intermediate products produced by the pentose phosphate pathway and coenzyme Q had a positive effect on steroid hormone biosynthesis to combat intestinal inflammation.

Genome-Wide Identification and Characterization of Circular RNAs during Skeletal Muscle Development in Meat Rabbits

Simple Summary

Our knowledge of circRNAs regulating skeletal muscle development remains largely unknown in meat rabbits. Therefore, we collected the leg muscle tissues of ZIKA rabbits at three key growth stages. A combination of circRNA assembly from a circRNA-seq library and the whole-transcriptome sequencing data identified credible circRNAs in our samples. We found these circRNAs were more conserved between rabbits and humans than between rabbits and mice. A prediction of circRNA–microRNA–mRNAs networks revealed that circRNAs might be the regulators that mainly functioned in rabbits’ muscle neuron development and metabolic processes. Our work provides a catalog of circRNAs regulating skeletal muscle development at key growth stages in rabbits and might give a new insight into rabbit breeding.

Abstract

Skeletal muscle development plays a vital role in muscle quality and yield in meat rabbits. Circular RNAs (circRNAs) are a new type of single-stranded endogenous non-coding RNAs involved in different biological processes. However, our knowledge of circRNAs regulating skeletal muscle development remains largely unknown in meat rabbits. In this study, we collected the leg muscle tissues of ZIKA rabbits at three key growth stages. By performing whole-transcriptome sequencing, we found the sequential expression of day 0- (D0-), D35-, and D70-selective mRNAs mainly functioned in muscle development, nervous development, and immune response during skeletal muscle development, respectively. Then, a combination of circRNA assembly from a circRNA-seq library and the whole-transcriptome sequencing data identified 6845 credible circRNAs in our samples. Most circRNAs were transcribed from exons of known genes, contained few exons, and showed short length, and these circRNAs were more conserved between rabbits and humans than between rabbits and mice. The upregulated circRNAs, which were synchronously changed with host genes, primarily played roles in MAPK signaling pathways and fatty acid biosynthesis. The prediction of circRNA–microRNA–mRNAs networks revealed that circRNAs might be the regulators that mainly functioned in rabbits’ muscle neuron development and metabolic processes. Our work provides a catalog of circRNAs regulating skeletal muscle development at key growth stages in rabbits and might give a new insight into rabbit breeding.

Effect of cooking methods on the edible, nutritive qualities and volatile flavor compounds of rabbit meat

BACKGROUND

Rabbit meat is a good edible meat source with high nutritional values. Cooking has a significant impact on the edible properties, nutritional qualities and flavor characteristics of meat. Studying the effect of cooking methods on rabbit meat qualities could encourage more understanding and acceptance of rabbit meat by consumers, and could also provide some reference for rabbit meat processing. Therefore, the effects of boiling, sous-vide cooking, steaming, microwaving, roasting, frying and pressure cooking on the edible, nutritive and volatile qualities of rabbit meat were investigated.

RESULTS

The sous-vide cooked rabbit meat sample showed higher moisture content, water-holding capacity and lower cooking losses than other samples, but the results of roasted rabbit meat sample were the opposite, and scanning electron microscopy observations also verified the results. There was no significant difference in 2-thiobarbituric acid reactive substance (TBARS) value in the cooked samples except for roasting. Microwaving, roasting and frying exhibited stronger antioxidant activity than the other cooked samples after in vitro digestion. A total of 38 volatiles were identified in the cooked meat samples, and the samples were well divided into four groups by principal component analysis, and 13 volatiles were considered discriminatory variables for the cooked rabbit meat.

CONCLUSION

The physicochemical characteristics of cooked meat differed significantly between the processing methods. Roasted meat showed lower TBARS value and stronger antioxidant activity after simulated digestion compared to the other meats. However, pressure cooked meat detected the most volatile components while roasting the least. © 2022 Society of Chemical Industry.

The purchase willingness of consumers for red meat in China

The aim of this study was to explore the purchase willingness of Chinese consumers for pork, beef, lamb, and rabbit meat. A conceptual framework and focus group discussions were adopted to design the questionnaire which included experience, eating habits, purchase drivers, purchase location, seasonality, and willingness to purchase red meat among Chinese consumers. Data collection was undertaken using an online platform questionnaire, with 4039 meat consumers participating in this study. By constructing the partial least squares - path modeling (PLS-PM) to explore the concerns of Chinese consumers while purchasing various types of red meats as well as the effect of these questions on consumers' willingness intensity to purchase red meat. Willingness intensity to purchase lamb is significantly affected by experience, seasonality, purchase location, eating habits, willingness, purchase drivers, and personal information; beef is affected by experience, seasonality, purchase location, eating habits, willingness, and personal information; pork is mainly affected by eating habits and purchase drivers; while eating habits, purchase location, and personal information have positive impacts on willingness intensity to purchase rabbit meat. This study developed the orthogonal matching pursuit - stochastic gradient descent (OMP-SDG) model, which integrated the questionnaire collecting personal information with the questionnaire on Chinese consumers' perceptions of red meat. The program can more precisely forecast which types of red meat people like and their degree of willingness. Finally, Chinese consumers preferred beef, lamb, pork, and rabbit meat in that order. They also prefer local meat, believing it to be of high quality and providing a satisfactory sensory experience, appearance, and saturation.

Safety and Efficacy of the Bordetella bronchiseptica Vaccine Combined with a Vegetable Oil Adjuvant and Multi-Omics Analysis of Its Potential Role in the Protective Response of Rabbits

Infectious respiratory diseases caused by Bordetella bronchiseptica (Bb) are seriously endangering the development of the rabbit industry in China. Unfortunately, no licensed vaccines are available for this pathogen. The present study was designed to determine whether the inactivated Bb antigen formulated with vegetable oil adjuvant (named E515) which contains soybean oil, vitamin E, and ginseng saponins, functions as a safe and effective vaccine (E515-Bb) against Bb infection in rabbits. Based on local and systemic reactions, both the E515 adjuvant alone and the E515-Bb vaccine exhibited good safety in rabbits. Immune response analysis implies that rabbits immunized with the E515-Bb vaccine produced significantly higher, earlier, and longer-lasting specific antibody responses and activated Th1/Th2/Th17 cell responses than those immunized with the aluminum hydroxide (Alum)-adjuvanted Bb vaccine (Alum-Bb) or Bb antigen alone. Moreover, the E515-Bb vaccine effectively protected rabbits from Bb infection. Additionally, integrated multi-omics analysis revealed that the immunoprotective effect of the E515-Bb vaccine was achieved through upregulation of the complement and coagulation cascades and cell adhesion molecule (CAM) pathways, and the downregulation of the P53 pathway. Overall, these results indicate that the E515-Bb vaccine is safe, elicits an efficient immune response and provides good protection against Bb infection in rabbits. Thus, the E515-adjuvanted Bb vaccine can be considered a promising candidate vaccine for preventing Bb infection.

Circular RNA, microRNA and Protein Profiles of the Longissimus Dorsi of Germany ZIKA and Sichuan White Rabbits

Due to the dietetic properties and remarkable nutritive value of rabbit meat, its industry is increasing rapidly. However, the association between circular RNAs, microRNAs, and proteins and muscle fiber type, and meat quality of rabbit is still unknown. Here, using deep sequencing and iTRAQ proteomics technologies we first identified 3159 circRNAs, 356 miRNAs, and 755 proteins in the longissimus dorsi tissues from Sichuan white (SCWrabs) and Germany great line ZIKA rabbits (ZIKArabs). Next, we identified 267 circRNAs, 3 miRNAs, and 29 proteins differentially expressed in the muscle tissues of SCWrabs and ZIKArabs. Interaction network analysis revealed some key regulation relationships between noncoding RNAs and proteins that might be associated with the muscle fiber type and meat quality of rabbit. Further, miRNA isoforms and gene variants identified in SCWrabs and ZIKArabs revealed some pathways and biological processes related to the muscle development. This is the first study of noncoding RNA and protein profiles for the two rabbit breeds. It provides a valuable resource for future studies in rabbits and will improve our understanding of the molecular regulation mechanisms in the muscle development of livestock. More importantly, the output of our study will benefit the researchers and producers in the rabbit breeding program.

Specifics of the morphological identification of the pathogen of passaluariasis of rabbits

Passalurus ambiguus (Nematoda, Oxyuroidae) is one of the most common parasites of digestive tract of domestic and wild rabbits and rodents. Passalurus spp. are cosmopolitan, and the mature nematodes are localized in the appendages and large intestine of animals. The passaluariasis infections remain quite relevant in modern rabbit breeding, because the disease is highly contagious, with the possibility of unlimited spread inducing significant economic losses. The aim of the study was to determine the identifying morphological species characteristics of P. ambiguus nematodes, which were isolated from the colon of domestic rabbits (Oryctolagus cuniculus domesticus). The identifying characters of Passalurus include morphological features, namely the presence of a spherical bulb in the esophagus, and the presence of three teeth in the oral capsule. Males of P. ambiguus have a characteristic structure of the tail end, namely the presence of papillary protrusions and a massive narrowed part with a spicule handle, and five papillae around the cloaca. Twenty-eight metric indicators are proposed that characterize the size of the body, oral capsule, esophagus in different parts of it, the tail end, spicules, the location of the cloaca. Two different morphotypes of mature females of P. ambiguus were revealed – short-tailed and long-tailed, which were larger by 19 indicators (by 3.2–43.6%). The morphotypes of P. ambiguus females are characterized; the length of the tail, body length and width in different areas, depth of the oral capsule, esophageal size and its structural elements, the location of the vulva and nerve ring, the width of the caudal process. At the same time, the parameters of esophageal bulb length and caudal process in short-tailed females were higher (by 13.9% and 11.9%, respectively) than in the long-tailed females. A total of 25 morphometric parameters were proposed for the identification of P. ambiguus females. The obtained data indicate the feasibility of further research on the causes of occurrence of such morphotypes in P. ambiguus females and the need to take into account the existence of such forms of females for their differential diagnosis taking into account their proposed morphometric parameters.

Aggregation and deaggregation: The effect of high-pressure homogenization cycles on myofibrillar proteins aqueous solution

Myofibrillar proteins (MPs) have not been fully used for a long time due to its poor solubility in low ionic strength solutions. The study explored the effect of high pressure homogenization (HPH) cycles under two pressures on the solubility of MPs. The MPs solubility increased with HPH cycles (p < 0.05), the results of turbidity, appearance, droplet size indicated that the increase of solubility was due to MPs depolymerization, excessive HPH cycles (25k psi for 11 cycles) would lead to protein re-aggregation but does not affect solubility (p>0.05). SDS-PAGE suggested that myosin formed soluble polymers with different molecular weights through disulfide bonds during HPH cycles, the polymer consisted of myosin subunits of different molecular weights. Endogenous fluorescence spectra, intermolecular chemical forces, isoelectric point analysis and free amino acids (FAAs) indicated that the dissolution of polymers in low ionic strength media was dominated by polar environment and intermolecular steric hindrance, but not to FAAs.

Genome-Wide Association Studies for Growth Curves in Meat Rabbits Through the Single-Step Nonlinear Mixed Model

Growth is a complex trait with moderate to high heritability in livestock and must be described by the longitudinal data measured over multiple time points. Therefore, the used phenotype in genome-wide association studies (GWAS) of growth traits could be either the measures at the preselected time point or the fitted parameters of whole growth trajectory. A promising alternative approach was recently proposed that combined the fitting of growth curves and estimation of single-nucleotide polymorphism (SNP) effects into single-step nonlinear mixed model (NMM). In this study, we collected the body weights at 35, 42, 49, 56, 63, 70, and 84 days of age for 401 animals in a crossbred population of meat rabbits and compared five fitting models of growth curves (Logistic, Gompertz, Brody, Von Bertalanffy, and Richards). The logistic model was preferably selected and subjected to GWAS using the approach of single-step NMM, which was based on 87,704 genome-wide SNPs. A total of 45 significant SNPs distributed on five chromosomes were found to simultaneously affect the two growth parameters of mature weight (A) and maturity rate (K). However, no SNP was found to be independently associated with either A or K. Seven positional genes, including KCNIP4, GBA3, PPARGC1A, LDB2, SHISA3, GNA13, and FGF10, were suggested to be candidates affecting growth performances in meat rabbits. To the best of our knowledge, this is the first report of GWAS based on single-step NMM for longitudinal traits in rabbits, which also revealed the genetic architecture of growth traits that are helpful in implementing genome selection.

High occurrence of carbapenem-resistant Escherichia coli isolates from healthy rabbits (Oryctolagus cuniculus): first report of blaIMI and blaVIM type genes from livestock in Tunisia

We aimed to study the antibiotic susceptibility and possible occurrence of extended-spectrum beta-lactamases (ESBL)/carbapenemase-producing Escherichia coli isolates collected from rabbits in Tunisia. In all, 35 faecal samples from healthy rabbits were collected from one farm and E. coli were isolated from three media: antibiotic-free TBX agar, TBX+2 mg l^-1 cefotaxime and TBX+1 mg l^-1 imipenem. In total, 39 E. coli isolates were recovered; the majority showed resistance to at least one antibiotic and none was ESBL producer. Carbapenem resistance was detected in 16 isolates from either selective or un-selective media. Phenotypic methods used to detect carbapenemase production showed two positive isolates by Modified Hodge Test, six metallo-carbapenemase producers (Imipenem disc+EDTA) and all were temocillin resistant (possible OXA-48 carbapenemase). bla_VIM and bla_IMP type genes were detected in two and one isolates, respectively; one of them harboured both genes. Isolates contained common genes encoding resistance to sulphonamides (sul1, sul2), tetracycline (tetA, tetB, tetC) and fluoroquinolones (qnrS, aac(6')-Ib-cr). Class 1 and 2 integrons were detected in five and four isolates, respectively. These findings highlight the importance of rabbit production as reservoir of carbapenem-resistant E. coli and argument the first report of bla_VIM and bla_IMP genes in livestock in Tunisia.

Prevalence and multi-locus genotyping of Giardia duodenalis in rabbits from Shaanxi province in northwestern China

Giardia duodenalis is an important parasite with veterinary and public health significance worldwide. The presence and zoonotic assemblages of G. duodenalis have previously been reported in rabbits. In this study, to understand the infection status of G. duodenalis in rabbits from Shaanxi province, a total of 537 fecal samples were collected from two breeds of rabbits in four age groups (<30 days, 31–90 days, 91–200 days and >200 days) from four geographical origins (Fengxiang, Yangling, Tongchuan, and Shanyang). The presence of G. duodenalis in these samples was assessed using molecular assays based on beta-giardin (bg). The glutamate dehydrogenase (gdh) and triosephosphate isomerase (tpi) loci were then amplified in the bg-positive samples for multi-locus genotype (MLG) analysis. The total prevalence of G. duodenalis in these rabbits was 3.54% (19/537). Giardia duodenalis infection was found in both breeds of rabbits, and in all farms and age groups, but with no statistically significant differences related to these factors (p > 0.05). Two assemblages, including B and E, were identified, with the former the predominant assemblage detected in both breeds, and in all age groups and farms. Sequence analysis revealed 2 (named as rbg1-2), 1 (named as rtpi1), and 2 (named as rgdh1-2) haplotypes at the gene loci of bg, tpi, and gdh, respectively, forming a multilocus genotype (MLG) of assemblage B (rbg1, rtpi1, and rgdh1). These findings reveal the significant zoonotic potential and genetic diversity of G. duodenalis in rabbits in Shaanxi Province, PR China.

Modulation of Cathepsin S (CTSS) Regulates the Secretion of Progesterone and Estradiol, Proliferation, and Apoptosis of Ovarian Granulosa Cells in Rabbits

Simple Summary

In goat and sheep, CTSS is reported to be important for the development and maturation of oocytes by regulating cell proliferation and apoptosis. The purpose of this study was to investigate the role of CTSS in regulating cell apoptosis and hormone secretion in rabbit granulosa cells. Our results suggested that the CTSS gene can promote the proliferation of granulosa cells and reduce its apoptosis in vitro, while overexpression of CTSS promoted the secretion of progesterone and estrogen in rabbit granulosa cells. Therefore, manipulation of CTSS may improve development of oocytes, and thus provide an approach for better manipulation of rabbit reproductive performance.

Abstract

Cathepsin S (CTSS) is a member of cysteine protease family. Although many studies have demonstrated the vital role of CTSS in many physiological and pathological processes including tumor growth, angiogenesis and metastasis, the function of CTSS in the development of rabbit granulosa cells (GCS) remains unknown. To address this question, we isolated rabbit GCS and explored the regulatory function of the CTSS gene in cell proliferation and apoptosis. CTSS overexpression significantly promoted the secretion of progesterone (P4) and estrogen (E2) by increasing the expression of STAR and CYP19A1 (p < 0.05). We also found that overexpression of CTSS increased GCS proliferation by up-regulating the expression of proliferation related gene (PCNA) and anti-apoptotic gene (BCL2). Cell apoptosis was markedly decreased by CTSS activation (p < 0.05). In contrast, CTSS knockdown significantly decreased the secretion of P4 and E2 and the proliferation of rabbit GCS, while increasing the apoptosis of rabbit GCS. Taken together, our results highlight the important role of CTSS in regulating hormone secretion, cell proliferation, and apoptosis in rabbit GCS. These results might provide a basis for better understanding the molecular mechanism of rabbit reproduction.

Typology and sustainability assessment of rabbit farms in the urban and peri-urban areas of Southern Benin (West Africa)

<p>Analysis of production systems allows scientists to identify their weaknesses, particularly concerning production practices which require improvements at economic, social, and environmental levels. The present study aimed to characterise rabbit farms in the urban and peri-urban areas of South Benin and assess their sustainability using the DIAMOND method, a multicriteria sustainability assessment tool. Ninety-eight farmers were surveyed and individually interviewed. Categorical principal component and twostep cluster analyses were performed on information collected for a typology of farms. Sustainability scores were generated using the scoring scale of the DIAMOND tool. Five types of rabbit farms were identified as follows: modern extensive polyculture, traditional extensive monoculture, modern extensive monoculture, semi-intensive polyculture, and traditional extensive polyculture. Overall, all the rabbit farms had good scores for the economic sustainability pillar but were socially limited. They were all similar in their economic and environmental performances. In particular, semi-intensive farms were the most socially sustainable, whereas traditional farms (either in polyculture or monoculture) showed the lowest social performances. Furthermore, there were significant differences between farms for criteria relating to consumers’ demands and resource use. Semi-intensive farms responded best to consumers’ demands, whereas the traditional polyculture farm type was the most resource use efficient. Overall, in the urban and peri-urban areas of South Benin, the most sustainable rabbit farms were semi-intensive. Irrespective of farm type, positive coefficients of correlations were recorded among the three pillars of sustainability, being significant between the social and economic pillars on one hand, and between the social and environmental pillars on the other hand. These results suggest that efforts to improve farm social performance would also positively affect their economic and environmental performances and improve overall farm sustainability.</p>

Rabbits - their domestication and molecular genetics of hair coat development and quality

The European rabbit (Oryctolagus cuniculus) is the only representative of its genus living in present-day Europe and North Africa, and all domestic rabbits are descendants of this one species, which is native to the Iberian Peninsula. There are over 300 breeds of rabbits that differ in size, coat color, length of ears and type of fur. Rabbits are bred for various reasons, such as for laboratory animals and a source of meat, wool and fur, as well as for pets and exhibition animals. The hair coat is a important economic trait of rabbits. Its development and quality are influenced by various factors, both environmental and genetic. The genetic mechanisms underlying its development have not been thoroughly researched. The aim of this review is to discuss the domestication of rabbits and the different aspects of rabbit genetics. A brief review of the properties of rabbit hair coat, hair coat development and hair cycle will be provided, followed by discussion of the factors regulating hair coat development, molecular control of hair coat development and the role of non-coding RNAs in the regulation of gene expression in the hair follicles of rabbits. Information about genetic regulation of pathways could provide useful tools for improving hair coat quality and be of practical use in rabbit breeding.

Seminal Plasma Triggers the Differential Expression of the Glucocorticoid Receptor (NR3C1/GR) in the Rabbit Reproductive Tract

Rabbits are interesting as research animal models for reproduction, due to their condition of species of induced ovulation, with the release of endogenous gonadotropin-releasing hormone (GnRH) due to coitus. Glucocorticoid (GC) signaling, crucial for physiological homeostasis, is mediated through a yet unclear mechanism, by the GC receptor (NR3C1/GR). After mating, the female reproductive tract undergoes dynamic modifications, triggered by gene transcription, a pre-amble for fertilization and pregnancy. This study tested the hypothesis that when ovulation is induced, the expression of NR3C1 is influenced by sperm-free seminal plasma (SP), similarly to after mating (whole semen), along the different segments of the internal reproductive tract of female rabbits. Semen (mating) was compared to vaginal infusion of sperm-free SP (Experiment 1), and changes over time were also evaluated, i.e., 10, 24, 36, 68, and 72 h post-mating, corresponding to specific stages, i.e., ovulation, fertilization, and the interval of early embryo development up to the morula stage (Experiment 2). All does were treated with GnRH to induce ovulation. Samples were retrieved from seven segments of the reproductive tract (from the cervix to infundibulum), at 20 h post-mating or sperm-free SP infusion (Experiment 1) or at 10, 24, 36, 68, and 72 h post-mating (Experiment 2). Gene expression of NR3C1 was analyzed by qPCR. Results showed an increase in NR3C1 expression in the infundibulum compared to the other anatomical regions in the absence of spermatozoa when sperm-free SP infusion was performed (Experiment 1). Moreover, during the embryo transport through the oviduct, the distal isthmus was time-course upregulated, especially at 72 h, when morulae are retained in this anatomical region, while it was downregulated in the distal uterus at 68 h (Experiment 2). The overall results suggest that NR3C1, the GC receptor gene, assessed in the reproductive tract of does for the first time, shows differential expression changes during the interval of oviductal and uterine embryo transport that may imply a relevant role of the GC action, not only close to the site of ovulation and fertilization, but also in the endometrium.

Low-sodium dry-cured rabbit leg: A novel meat product with healthier properties

Dry-cured rabbit legs were produced with a 50% reduction or replacement of NaCl by KCl and with the addition of monosodium glutamate (MG). The effect of this reformulation on technological, nutritional, and sensory characteristics was evaluated. The sodium reformulation did not show a great impact on Aw, pH, weight loss, and volatile profile of the samples. The samples presented high protein (31.5 to 36.1%) and low fat contents (3.2 to 5.7%). In addition, all essential amino acids presented an amino acid score greater than 1.0. The reformulated samples showed a sodium reduction of 46.2% while the addition of KCl to the formulations provided a healthy Na/K ratio. Oleic acid was the major fatty acid (FA) (31.3% of total FA) and healthy lipid indexes were observed for all samples. Finally, the addition of MG was effective to compensate for the sensory defects caused by sodium reformulation.

Putting the Spring back into the Hare (Pedetes capensis): Meat Chemical Composition of an Underutilized Protein Source

Alternative protein sources are gaining increasing global attention as a solution to address future protein demands. Determining the chemical composition of meat alternatives is vital to confirm that it is nutritious, but also to increase product value and promote its utilization. The carcass characteristics and chemical composition of springhare, an underutilized protein source, was found to be comparable to that of commercially reared rabbits. Hence, its introduction into the commercial supply chain would likely not offset consumers accustomed to purchasing rabbit/hare meat. Springhare meat had a high protein content (~22.5 g/100 g meat) and low lipid (<1.3 g/100 g meat) content. The meat's fatty acids mainly comprised C18:2n6c (γ-linoleic acid; 24%), C18:0 (stearic acid; 20%), C16:0 (palmitic acid; 19%), C20:4n6 (arachidonic acid; 15%) and C18:1n9c (oleic acid; 13%). Although sex did not significantly influence the carcass characteristics and meat composition, season did have an effect (p < 0.05) on the fatty acid profile. The meat harvested in summer had higher (p < 0.05) concentrations of favorable unsaturated fatty acids, C18:2n6c, C18:3n6, C18:3n3 (α-linolenic acid), C20:2n6 (eicosadienoic acid), C20:3n3 (eicosatrienoic acid), compared to the meat obtained in winter, which contained more (p < 0.05) saturated fatty acids. The results verify that springhare can be utilized as a viable alternative protein source.

LC-QTOF-MS identification of rabbit-specific peptides for authenticating the species composition of meat products

Rabbit is a healthy meat, with low allergenicity and excellent nutritional properties. The global popularity of rabbit meat makes it a target for food fraud. We present a LC-QTOF-MS/MS approach for detecting and identifying rabbit-specific peptide-markers from thermally processed meat products to differentiate rabbit from other commonly-consumed animal species. We identified 49 heat-stable specific peptides. We selected the most stable markers for testing complex meat matrices by analysing pâtés-type products with a rabbit meat content ranging from 5% to 85%. Of the 49 heat-stable peptides detected in pure cooked rabbit meat, three were consistently detected in all investigated pâté samples i.e., SSVFVADPK, AFFGHYLYEVAR and PHSHPALTPEQK. Monitoring meat species other than rabbit in the examined pâtés using pork-, lamb- and chicken-specific peptides identified the presence of undeclared chicken in two samples. The results confirm that LC-QTOF-MS/MS is a suitable tool for multi-species detection in processed meat products, particularly for authentication purposes.

Consumers' Attitude to Consumption of Rabbit Meat in Eight Countries Depending on the Production Method and Its Purchase Form

Simple Summary

The aim of the study was to investigate the consumers’ attitude to their preference of rabbit meat in eight countries depending on the production method and its purchase form. Consumers’ attitude was evaluated in Spain, Italy, France, Poland, Hungary, China, Brazil and Mexico based on the respondents’ opinion regarding origin, production conditions, slaughtering methods and breed. Results revealed that breed was an inessential factor. The origin of rabbits was the most important in Italy, France, Hungary and Brazil (in the latter country the slaughtering method and the level of processing were also highly valued), feeding of animals received the highest scores in Spain, Poland and Mexico (in the latter also the slaughtering method), while the level of processing was the foremost factor in China. The preference of fresh meat was the highest in Spain, France and Mexico, and that of frozen in Brazil and Mexico. The highest preference of a whole carcass was found in France and Mexico. The thigh was mostly favored in France and that of the loin in Mexico. The prepared meat products (roasted, smoked and semi-finished) were the most popular in Mexico. It can be concluded the preference of respondents depended on the country.

Abstract

The study’s aim was to investigate the consumers’ attitude to their preference of rabbit meat in eight countries depending on the production method and its purchase form. In Spain and China almost all factors got low scores. High scores (above 4 out of 5) for origin were found in Italy, France, Poland, Hungary and Brazil. The importance of feeding was highlighted in Italy, Poland, Hungary and Mexico. High values were received for housing conditions in Italy, Poland, Hungary and Mexico. The level of processing was the most important in China and Brazil, while the slaughtering method was considered the most important in Brazil and Mexico. Breed received the lowest score in almost all countries. The preference of fresh meat was the highest (above 50%) in Spain, France and Mexico, and that of frozen in Brazil and Mexico (about 20%). The highest preference for a whole carcass (above 50%) was given by the respondents in France and Mexico. Thigh was mostly preferred in France whereas consumers preferred loin in Mexico. Roasted, smoked and semi-finished forms were mostly favored in Mexico. It can be concluded that the preference of respondents depended on the country. Preferences were different among the Mediterranean countries, and also Latin American countries.

Prevalence and Genotype Distribution of Giardia duodenalis in Rabbits in Shandong Province, Eastern China

Giardia duodenalis is a zoonotic enteric parasite that can infect humans and a number of animal species including rabbits with a worldwide distribution. Infection with G. duodenalis can cause serious public health problems and significant economic losses to animal husbandry. So accurate understanding of the prevalence and genotype distribution of G. duodenalis in rabbits is necessary. In the present study, a total of 616 fecal samples were collected from rabbits in Shandong province, eastern China, and examined in G. duodenalis prevalence and genotypes by nested PCR amplification of β-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) gene loci of G. duodenalis. Sixty-nine (11.2%) of the examined rabbit fecal samples were G. duodenalis-positive. Of them, the prevalence of G. duodenalis is 8.4% (41/490) in Rizhao city and 22.2% (28/126) in Weihai city. Breeds, region, and feeding modes were highly correlated with G. duodenalis infection in rabbits. Moreover, three genotypes (assemblages A, B, and E) were identified in rabbits at three gene loci, and the assemblage E was the dominant genotype, while the assemblage A was reported in rabbits in China for the first time. It is noticeable that two rabbits were found to be infected with two different G. duodenalis assemblages (assemblages A and E, assemblages B and E, respectively). These findings enrich the genotype distribution of G. duodenalis in rabbits and provide baseline data for preventing and controlling G. duodenalis infection in rabbits in eastern China.