Rex Rabbits Research Articles

Fermented Yupingfeng polysaccharides enhance immunity by improving the foregut microflora and intestinal barrier in weaning rex rabbits.

Yupingfeng (YPF) is a kind of Astragali radix-based ancient Chinese herbal supplemented with Atractylodis Macrocephalae Rhizoma and Radix Saposhnikoviae. Increasing evidence has proven the beneficial immunomodulating activity of YPF. However, the action mechanism(s) of it is not known. Here, we explored the immunomodulatory activity of unfermented Yupingfeng polysaccharides (UYP) and fermented Yupingfeng polysaccharides (FYP) obtained using Rhizopus oligosporus SH in weaning Rex rabbits. The results showed that both UYP and FYP exhibited notable growth-promoting and immune-enhancing activities, improvement of the intestinal flora homeostasis, and maintenance of intestinal barrier integrity and functionality. Notably, compared with UYP, FYP effectively enhanced average daily gain, organ indices, interleukin-2 (IL-2), IL-4, IL-10, tumor necrosis factor-alpha (TNF-α), TLR2, and TLR4 mRNA levels in spleen, IL-1, IL-2, IL-4, IL-6, IL-10, IL-12, TNF-α, and IFN-γ protein concentrations in serum, and TLR2 and TLR4 mRNA expressions in the gastrointestinal tract (GIT). Moreover, FYP exhibited greater beneficial effects in improving the intestinal flora, including augment flora diversity and the abundance of cellulolytic bacteria, reduction the abundance of Streptococcus spp. and Enterococcus spp. in the GIT, particularly the foregut and maintaining the intestinal barrier integrity and functionality by upregulating zonula occludens 1, claudin, polymeric immunoglobulin receptor, trefoil factor, and epidermal growth factor mRNA levels in the jejunum and ileum. Our results indicated the immunoenhancement effect of FYP is superior over that of UYP, which is probably related with the amelioration of the intestinal microflora and intestinal barrier in the foregut.

Dietary Niacin Supplementation Suppressed Hepatic Lipid Accumulation in Rabbits.

An experiment was conducted to investigate the effect of niacin supplementation on hepatic lipid metabolism in rabbits. Rex Rabbits (90 d, n = 32) were allocated to two equal treatment groups: Fed basal diet (control) or fed basal diet with additional 200 mg/kg niacin supplementation (niacin). The results show that niacin significantly increased the levels of plasma adiponectin, hepatic apoprotein B and hepatic leptin receptors mRNA (p<0.05), but significantly decreased the hepatic fatty acid synthase activity and adiponectin receptor 2, insulin receptor and acetyl-CoA carboxylase mRNA levels (p<0.05). Plasma insulin had a decreasing tendency in the niacin treatment group compared with control (p = 0.067). Plasma very low density lipoproteins, leptin levels and the hepatic adiponectin receptor 1 and carnitine palmitoyl transferase 1 genes expression were not significantly altered with niacin addition to the diet (p>0.05). However, niacin treatment significantly inhibited the hepatocytes lipid accumulation compared with the control group (p<0.05). In conclusion, niacin treatment can decrease hepatic fatty acids synthesis, but does not alter fatty acids oxidation and triacylglycerol export. And this whole process attenuates lipid accumulation in liver. Besides, the hormones of insulin, leptin and adiponectin are associated with the regulation of niacin in hepatic lipid metabolism in rabbits.

Effect of varying the energy density on growth performance, meat quality, caecum fermentation and microbiota of growing Rex rabbits

An experiment was conducted to determine the effects of varying the digestible energy (DE) density on growth performance, meat quality, caecum fermentation and microbiota in 3–5-month-old Rex rabbits. One-hundred and eighty 3-month-old Rex rabbits were allocated in individual cages to five treatments with diets having DE levels (MJ/kg as-fed basis) of 9.46, 9.97, 10.46, 10.94 and 11.43, respectively. The results showed as follows: with increasing DE concentration the average daily gain, muscle pH value of 45 min post-mortem, caecal pH value and NH3-N concentration increased (P &lt; 0.05). Bacterial denaturing gradient gel electrophoresis (denaturing gradient gel electrophoresis) of partial 16S rRNA genes profiles were clearly different among different treatments, which suggests that the population of microorganism in the caecum was influenced by the dietary DE density.

Transcriptome expression profiling of fur color formation in domestic rabbits using Solexa sequencing.

Fur color is an important, genetically determined characteristic of domestic rabbits, and rabbit furs are of great economic value. To investigate the molecular genetics associated with fur color determination in domestic rabbits, we used Solexa-sequencing technology to probe gene expression in dorsal skin tissues sampled from full-sibling Rex rabbits of different colors. The number of expressed genes in each sample was approximately 14,700. Among the top 30 genes and transcription factors with the highest reads per kilobase per million values, the elongation factor-alpha 1 gene was highly expressed in all samples, as were genes of the ribosomal protein and keratin gene families. Compared with the chinchilla (C) Rex rabbit control sample, the numbers of genes in the black (B) and white (W) rabbit samples were 1809 and 460, respectively, and the number of common differentially expressed genes was 257. Clustering analysis of these 257 genes revealed that 32 were up-regulated in sample B and down-regulated in sample W. Of these 32 genes, we identified some that are related to fur formation, including Tyrosinase-related protein 1 (TYRP1) and Tyrosinase (TYR), as well as genes with unknown functions. Quantitative real-time polymerase chain reaction was used to verify the expression patterns of those genes. The findings are expected to provide reference for the further study of fur color formation in rabbits.

Subtyping of Cryptosporidium cuniculus and genotyping of Enterocytozoon bieneusi in rabbits in two farms in Heilongjiang Province, China.

Cryptosporidium spp. and Enterocytozoon bieneusi are two prevalent opportunistic pathogens in humans and animals. Currently, few data are available on genetic characterization of both pathogens in rabbits in China. The aim of the present study was to understand prevalence and genetic characterization of Cryptosporidium spp. and E. bieneusi in rabbits. We collected 215 fecal samples from 150 Rex rabbits and 65 New Zealand White rabbits on two different farms in Heilongjiang Province, China. Cryptosporidium spp. and E. bieneusi were tested by polymerase chain reaction (PCR) and sequencing the partial small subunit of ribosomal DNA (SSU rDNA) and the internal transcribed spacer (ITS) region of rDNA, respectively. Cryptosporidium was detected in 3.3% (5/150) of Rex rabbits and 29.2% (19/65) of New Zealand White rabbits. All the 24 Cryptosporidium isolates were identified as C. cuniculus. Enterocytozoon bieneusi was only found in 14.7% (22/150) of Rex rabbits. Five known genotypes: CHN-RD1 (n = 12), D (n = 3), Type IV (n = 2), Peru6 (n = 1), and I (n = 1), and three novel ones CHN-RR1 to CHN-RR3 (one each) were detected. By analyzing the 60-kDa glycoprotein (gp60) gene sequences of C. cuniculus isolates, three subtypes were obtained: VbA28 (n = 2), VbA29 (n = 16), and VbA32 (n = 3). All these three C. cuniculus subtypes were reported previously in humans. Four known E. bieneusi genotypes have been found to be present in humans. The three novel ones fell into zoonotic group 1. The results suggest zoonotic potential of C. cuniculus and E. bieneusi isolates in rabbits.

Solexa-Sequencing Based Transcriptome Study of Plaice Skin Phenotype in Rex Rabbits (Oryctolagus cuniculus).

BackgroundFur is an important genetically-determined characteristic of domestic rabbits; rabbit furs are of great economic value. We used the Solexa sequencing technology to assess gene expression in skin tissues from full-sib Rex rabbits of different phenotypes in order to explore the molecular mechanisms associated with fur determination.Methodology/Principal FindingsTranscriptome analysis included de novo assembly, gene function identification, and gene function classification and enrichment. We obtained 74,032,912 and 71,126,891 short reads of 100 nt, which were assembled into 377,618 unique sequences by Trinity strategy (N50=680 nt). Based on BLAST results with known proteins, 50,228 sequences were identified at a cut-off E-value ≥ 10-5. Using Blast to Gene Ontology (GO), Clusters of Orthologous Groups (KOG) and Kyoto Encyclopedia of Genes and Genomes (KEGG), we obtained several genes with important protein functions. A total of 308 differentially expressed genes were obtained by transcriptome analysis of plaice and un-plaice phenotype animals; 209 additional differentially expressed genes were not found in any database. These genes included 49 that were only expressed in plaice skin rabbits. The novel genes may play important roles during skin growth and development. In addition, 99 known differentially expressed genes were assigned to PI3K-Akt signaling, focal adhesion, and ECM-receptor interactin, among others. Growth factors play a role in skin growth and development by regulating these signaling pathways. We confirmed the altered expression levels of seven target genes by qRT-PCR. And chosen a key gene for SNP to found the differentially between plaice and un-plaice phenotypes rabbit.Conclusions/SignificanceThe rabbit transcriptome profiling data provide new insights in understanding the molecular mechanisms underlying rabbit skin growth and development.

The bacterial communities associated with fecal types and body weight of rex rabbits

Rex rabbit is an important small herbivore for fur and meat production. However, little is known about the gut microbiota in rex rabbit, especially regarding their relationship with different fecal types and growth of the hosts. We characterized the microbiota of both hard and soft feces from rex rabbits with high and low body weight by using the Illumina MiSeq platform targeting the V4 region of the 16S rDNA. High weight rex rabbits possess distinctive microbiota in hard feces, but not in soft feces, from the low weight group. We detected the overrepresentation of several genera such as YS2/Cyanobacteria, and Bacteroidales and underrepresentation of genera such as Anaeroplasma spp. and Clostridiaceae in high weight hard feces. Between fecal types, several bacterial taxa such as Ruminococcaceae, and Akkermansia spp. were enriched in soft feces. PICRUSt analysis revealed that metabolic pathways such as “stilbenoid, diarylheptanoid, gingerol biosynthesis” were enriched in high weight rabbits, and pathways related to “xenobiotics biodegradation” and “various types of N-glycan biosynthesis” were overrepresented in rabbit soft feces. Our study provides foundation to generate hypothesis aiming to test the roles that different bacterial taxa play in the growth and caecotrophy of rex rabbits.

Sequence and Gene Expression Analysis of the Agouti Signalling Protein Gene in Rex Rabbits with Different Coat Colours

Rex rabbits have a unique fur structure with a variety of different coat colours. In this study, we analysed variability in the agouti signalling protein (ASIP) gene in Rex rabbits with different coat colours (castor, red, blue, chinchilla, otter and black). Three alleles at this locus were identified: A, light-bellied agouti (wild type), in castor and chinchilla Rex; đ, black and tan, in otter, castor and chinchilla Rex; and a, black non-agouti, in black, red, blue, castor and chinchilla Rex rabbits. Two missense mutations, two synonymous substitutions and one indel were the identified polymorphisms associated to these three alleles, as already described by others. Gene expression of the ASIP gene was also evaluated in different tissues from animals of the six coat colours. Agouti signalling protein expression was always observed in all tissue/coat colour combinations.

Evaluation of Protein Concentrate from Jatropha Seed Cake as a Soybean Meal Substitution in the Rabbit Feed

Abstract This research aimed is to evaluated post fermented protein concentrate from jatropha seed cake by using it as feed and the effect on blood metabolite of post weaned Rex rabbits ( Oryctolagus cuniculus ). Variables investigated were feed consumption and blood metabolite profiles (triglycerides and glucose). Analysis of variance showed significant effect on feed consumption and level blood glucose (P 0,05). Based on feed intake and blood metabolite profiles, the experiment resulted that soybean meal can be substituted with protein concentrate from jatropha seed cake as a feed of post weaned Rex rabbits.

Biorefinery of Jatropha Seed Cake by Lactid Acid Bacteria and the Effects on Hematological Profile of Rex Rabbit

This research aimed: to increase the added value of Jatropha cultivation by using it as rabbit feed and to analyze the fermentation of Jatropha seed cake by lactic acid and the effect on blood profile of post weaned Rex rabbits. The range and analysis of variance of PCV, trombocyte, TPP and fibrinogen are presented in these documents. Conclusion, to increase the added value of Jatropha cultivation is by utilizing the seed cake as complete feed for rabbits up to 12% level without affecting the blood profile of post weaned Rex rabbits.

Controlled delivery of growth‐hormone‐releasing peptide 6 from the poly(lactic‐co‐glycolic acid)–poly(ethylene glycol)–poly(lactic‐co‐glycolic acid) copolymer and the effect of a growth‐hormone‐releasing peptide 6–copolymer hydrogel on the growth of rex rabbits

ABSTRACTGrowth‐hormone‐releasing peptide 6 (GHRP‐6) plays an important role in animal growth. However, there have been few studies focusing on the effect of GHRP‐6 on animal growth through controlled release systems. We synthesized the poly(lactic‐co‐glycolic acid) (PLGA)–poly(ethylene glycol) (PEG)–PLGA copolymer to investigate its controlled released effect on GHRP‐6 in vitro and to study the effect of a GHRP‐6–copolymer hydrogel on the growth of rex rabbits. The copolymer was synthesized with ring‐opening copolymerization and characterized by 1H‐NMR. The interaction between GHRP‐6 and the copolymer was characterized by Fourier transform infrared spectroscopy and X‐ray diffraction. The body weight, serum level of insulin‐like growth factor 1 (IGF‐1), and hair coat quality were studied in rex rabbits. The results show that hydrogen bonds formed between the NH group in GHRP‐6 and the CO group in the copolymer. The release mechanism of GHRP‐6 was a combination of a diffusion‐controlled mechanism and an erosion‐controlled mechanism in the copolymer. The serum level of IGF‐1, hair coat quality, and body weight were all significantly higher in the GHRP‐6–copolymer hydrogel group than in the other groups. These results indicate that the copolymer effectively controlled the release of GHRP‐6. In addition, the GHRP‐6–copolymer hydrogel increased the synthesis of IGF‐1 for a prolonged period and, thereby, increased the rex rabbits' growth and hair coat quality. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40185.

Discovery and genetic analysis of blue-eyed mutant in the white rex rabbits

Using cross, backcross, and full-sib mating experiments, allelism test was conducted to study the genetic mechanism of blue-eyed mutant of the white rex rabbits originated from the F1 generation from the cross American White rex rabbits(♂) × Chinchilla meat rabbits(♀). The study showed that the reason for the blue-eyed mutant of the white rex rabbits was a recessive mutation in Vienna locus. When the V locus was homozygous for the recessive v gene, it was recessive epistatic to other loci (including A, B, C, D, and E), which also controlled the coat color. Regardless of the genotypes in other gene loci, the rabbits appeared blue eyes and white coat color as long as the genotype vv occurred at the Vienna locus. Thus, the combination of genotype vv and genotype rr will produce the blue-eyed and the white rex rabbits. As the blue-eyed mutant of the white rex rabbits is a new finding in China's rabbit breeding program, it is significant to explain the genetic mechanism of the blue-eyed mutant for the breeding and production of rex rabbits.

Study on Effect of Chinese Herbal Medicine Additives on Meat, Fur and Hide Quality of Rex Rabbits

Study on Effect of Chinese Herbal Medicine Additives on Meat, Fur and Hide Quality of Rex Rabbits

Effects of chronic heat stress on the reproductive capacity of male Rex rabbits

The effects of chronic heat stress on the reproductive system of rabbits have not been thoroughly examined. Therefore, we investigated the effects of heat stress on the reproductive performance of male Rex rabbits and documented the recovery process after stress withdrawal. Thirty age-matched, male Rex rabbits were placed into artificial climate chambers and randomly divided into three groups: control, heat stress, and recovery. Our results indicate that both libido of rabbit and sperm density were decreased significantly during the 9weeks exposure to heat stress. Semen volume was mildly affected. Histomorphological and TUNEL assay results showed that chronic heat treatment adversely affected microscopic structure of the testes, and elevated the apoptosis of germ cells in the seminiferous tubules distinctly. However, these adverse effects induced by heat were transient as all measured parameters returned to control levels following the recovery period.

LIPH expression in skin and hair follicles of normal coat and Rex rabbits.

Natural mutations in the LIPH gene were shown to be responsible for hair growth defects in humans and for the rex short hair phenotype in rabbits. In this species, we identified a single nucleotide deletion in LIPH (1362delA) introducing a stop codon in the C-terminal region of the protein. We investigated the expression of LIPH between normal coat and rex rabbits during critical fetal stages of hair follicle genesis, in adults and during hair follicle cycles. Transcripts were three times less expressed in both fetal and adult stages of the rex rabbits than in normal rabbits. In addition, the hair growth cycle phases affected the regulation of the transcription level in the normal and mutant phenotypes differently. LIPH mRNA and protein levels were higher in the outer root sheath (ORS) than in the inner root sheath (IRS), with a very weak signal in the IRS of rex rabbits. In vitro transfection shows that the mutant protein has a reduced lipase activity compared to the wild type form. Our results contribute to the characterization of the LIPH mode of action and confirm the crucial role of LIPH in hair production.

A Deletion in Exon 9 of the LIPH Gene Is Responsible for the Rex Hair Coat Phenotype in Rabbits (Oryctolagus cuniculus)

The fur of common rabbits is constituted of 3 types of hair differing in length and diameter while that of rex animals is essentially made up of amazingly soft down-hair. Rex short hair coat phenotypes in rabbits were shown to be controlled by three distinct loci. We focused on the “r1” mutation which segregates at a simple autosomal-recessive locus in our rabbit strains. A positional candidate gene approach was used to identify the rex gene and the corresponding mutation. The gene was primo-localized within a 40 cM region on rabbit chromosome 14 by genome scanning families of 187 rabbits in an experimental mating scheme. Then, fine mapping refined the region to 0.5 cM (Z = 78) by genotyping an additional 359 offspring for 94 microsatellites present or newly generated within the first defined interval. Comparative mapping pointed out a candidate gene in this 700 kb region, namely LIPH (Lipase Member H). In humans, several mutations in this major gene cause alopecia, hair loss phenotypes. The rabbit gene structure was established and a deletion of a single nucleotide was found in LIPH exon 9 of rex rabbits (1362delA). This mutation results in a frameshift and introduces a premature stop codon potentially shortening the protein by 19 amino acids. The association between this deletion and the rex phenotype was complete, as determined by its presence in our rabbit families and among a panel of 60 rex and its absence in all 60 non-rex rabbits. This strongly suggests that this deletion, in a homozygous state, is responsible for the rex phenotype in rabbits.

Gene Expression Patterns in Different Wool Densities of Rex Rabbit Using cDNA Microarray

This study was carried out to identify gene expression patterns in different wool densities of rex rabbit. The mid-dorsal skin samples from 8 rex rabbits were studied. They were divided into two groups according to different wool densities. Total RNA was isolated and labeled by reverse transcription reaction with Cy5-dCTP and Cy3-dCTP for cDNA probe. The cDNA probe was hybridized with cDNA microarrays containing 14 601 rabbit's genes. The differently expressed genes were analysed with the Gene Ontology (GO) classification and the pathway analysis. Hierarchical clustering was performed to clarify genes in association with different wool densities. The 2 657 differentially expressed genes were identified. Among them, 1 103 genes were functionally known genes, 687 genes were up-regulated and 419 were down-regulated. GO analysis indicated that these altered genes were associated with metabolism, signal transduction, cell cycle, cell adhesion, cell proliferation, cell division, apoptosis, and other processes. KEGG analysis showed that 95 signal pathways associated with up-regulated genes and 87 signal pathways associated with down-regulated genes had changed significantly ( P<0.05). Some important differentially expressed genes in different wool densities of rex rabbit were identified, such as MMP2, TGF-β1, TGF-β2, IGF-1, ITGB1, RPS6KB1, BMP2, ActRIIB, CDK2, and CCNA2. Hierarchical clustering analysis separated the differentially expressed genes into 5 main characteristic groups. Data from cDNA microarray experiments clearly distinguished between group A and group B. Some important genes were identified, which might be useful in further study on wool density markers of rex rabbit.

Effects of Taishan Pinus massoniana pollen polysaccharide on immune response of rabbit haemorrhagic disease tissue inactivated vaccine and on production performance of Rex rabbits

Varied doses of Taishan Pinus massoniana pollen polysaccharide (TPPPS) and Astragalus polysaccharide (APS) extracted by hot water extraction and ethanol precipiration method were added to the vaccine in order to prepare polysaccharide-rabbit haemorrhagic disease (RHD) tissue inactivated vaccine. The purpose was to study effects of TPPPS on immune response of RHD tissue inactivated vaccine and on production performance of Rex rabbits. Results showed that each index in groups I, II, III and IV was higher than that in group V, especially groups I, II and IV, the difference between which and group V was much more significant ( P < 0.05); each index in group I was extremely higher than that in group V ( P < 0.01); each index in group I was significantly higher than that in groups II, III ( P < 0.05), and generally no significant difference was observed between groups II and III. The overall level in group IV was slightly lower than that in group I. Each index in the polysaccharide groups reached its peak value later than that in the non-polysaccharide groups did. Results suggested that any dose of TPPPS can enhance immunologic function and production performance of rabbits, and the amount of 400 mg per rabbit has the most obvious efficacy. Furthermore, it can extend the immune peak period of RHD tissue inactivated vaccine and the growing peak period of Rex rabbits. TPPPS has generally higher efficiency than APS.

The serological prevalence and genetic diversity of hepatitis E virus in farmed rabbits in China

We identified and characterized a novel virus, designated rabbit hepatitis E virus (HEV), in rex rabbits farmed in China. Rabbit HEV is genetically related to but distinct from other known mammalian HEVs and avian HEV and may represent a novel genotype. To evaluate the spread and genetic variation of rabbit HEV, a total of 1094 serum samples were collected from various breeds of rabbits across ten counties in China. All sera were screened for the presence of anti-HEV antibody, HEV antigen and viral RNA. A total of 169 samples (15.4%), from nine of the ten counties, were found to be positive for HEV antibody. The seroprevalence was highest in Wuhan, Hunan Province (53.4%, 55/103). Samples positive for HEV antigen were detected in seven counties and the overall prevalence was 3.7% (41/1094). HEV RNA was detected in 22 samples and all but one of these samples was found to be positive for HEV antigen. Sequence analysis of the 304bp amplicons within open reading frame 2 showed that all HEV isolates in this study clustered with known rabbit HEV strains, in a branch separate from genotypes 1 to 4. The rabbit HEV strains were genetically heterogeneous and divided into divergent groups. Strains from the same geographic region tended to cluster together. These results indicate that rabbit HEVs with considerable genetic diversity are prevalent in farmed rabbits in China. The potential zoonotic risk of rabbit HEV needs to be investigated and evaluated further.

Identification of single nucleotide polymorphisms in the CCNA2 gene and its association with wool density in Rex rabbits

The Rex rabbit is a typical fur breed. Wool density, hair length, wool fineness, and hide area are the main indices of fur quality. We previously found that the CCNA2 gene plays an important role in hair follicle initiation and development, and it is involved in the distinctive wool density of the Rex rabbit. It is an important candidate gene for wool density selection through marker-assisted selection. We conducted an association study to identify single nucleotide polymorphisms (SNPs) within the CCNA2 gene and their ligands associated with wool density. Using PCR-RFLP technology, we discovered two SNPs (129G>A and 1140G>C) of the CCNA2 gene. Allele frequencies of these two SNPs were investigated and evaluated by the χ(2) test in 100 Rex rabbits. The two SNPs were both in Hardy-Weinberg equilibrium. We also looked for a potential association of these SNPs with fur traits in 100 Rex rabbits. Rex rabbits with the GG genotype had significantly higher wool density (P < 0.01) than those with other genotypes; the other three fur traits did not differ significantly among the genotypes. In conclusion, the two SNPs of the CCNA2 gene affect wool density in the Rex rabbit.