Effects of Diets with Different Corn-to-Soybean Ratios on Performance of Lactational Rex Rabbits

[ Objective] To study the effects of diets with different com-to-soybean ratios on production performance of lactational Rex rabbits and select the best feed formula. [Method] A total of 80 lactational healthy Rex rabbits （similar age, body weight and delivery time） were randomly divided into five groups, 16 in each group. The Rex rabbits in group I were fed with corn-based meal diet, group II with soybean-based meal diet, group III with the developed corn-soybean meal diet, group IV with corn-soybean meal free diet, and group CK with conventional corn-soybean meal diet. During the lactation period, the changes in the lactation performance, growth rate of baby rabbits, weight and feed costs were observed. [ Result] The lactation performance of mother rabbits and the growth rate of baby rabbits in the experimental groups were similar to that in the control group. The weaning survival rate of the group III was the highest, but it was not significantly higher than that of the control group. The weaning survival rate of the other three groups was lower than that of the control group （P〈0.05）. The weight loss of mother rabbits in the group I, II and III was not significantly different from that of the control group, but the weight loss of the group IV was higher than that of the control group （ P 〈 0.01 ）. [ Conclusion] Diets with appropriate corn-to-soybean ratios not only reduce feed costs but also give the best feeding effects.

Pyridoxine regulates hair follicle development via the PI3K/Akt, Wnt and Notch signalling pathways in rex rabbits

This study was conducted to evaluate the effect of pyridoxine on the development of hair follicles in Rex rabbits and the underlying molecular mechanism.Two hundred 3-month-old Rex rabbits were randomly divided into 5 groups and fed diets supplemented with 0,5,10,20,or 40 mg/kg pyridoxine.The hair follicle density on the dorsal skin and the gene and protein expression levels of components of the phosphoinositide 3-kinase(PI3 K)/protein kinase B(PKB or Akt),Wnt,Notch and bone morphogenetic protein(BMP)signalling pathways were measured.In addition,free hair follicles were isolated from Rex rabbits and cultured with pyridoxine in vitro to measure hair shaft growth.Furthermore,dermal papilla cells(DPC)were isolated from the skin of Rex rabbits and cultured with pyridoxine in vitro to measure the gene and protein expression levels of components of the PI3 K/Akt,Wnt,Notch and BMP signalling pathways.The results showed that the addition of dietary pyridoxine significantly increased the total follicle density,secondary follicle density,and secondary-to-primary ratio(S/P,P<0.05),that the growth ratio of hair stems was promoted by pyridoxine in basic culture medium,and that the growth length of tentacle hair follicles cultured in the pyridoxine group was longer than that in the control group(P<0.05).In addition,pyridoxine changed the DPC cycle progression and promoted cell proliferation,and appropriate concentrations of pyridoxine(10 and 20μmol/L)significantly inhibited cell apoptosis(P<0.05).Pyridoxine significantly affected the gene expression of components of the PI3 K/Akt,Wnt and Notch signalling pathways in the skin and DPC of Rex rabbits(P<0.05),increased the levels of phosphorylated catenin beta 1(CTNNB1)and Akt,and decreased the level of phosphorylated glycogen synthase kinase 3 beta(GSK-3β)(P<0.05).Therefore,the molecular mechanism by which pyridoxine promotes hair follicle density in Rex rabbits probably occurs through activation of the PI3 K/Akt,Wnt and Notch signalling pathways,prolonging hair follicle growth and delaying the onset of telogen.

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 （P0.05）. 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.

Differential Expression of CCNA2 Gene and MMP2 Gene in Skin Tissue of Rex Rabbit with Different Fur Densities

[ Objective] The paper was to search for the molecular marker highly associated with fur density of rex rabbit. [ Method ] Experimental rex rabbits were divided into dense fur group and sparse fur group. The variation rule of gene expression in skin tissue of rex rabbits with different fur densities was detected using rabbit whole gene cDNA microarray. [ Result] A total of 2 657 genes with differential expression were detected by microarray test, including 1 106 genes with known function, 687 genes with up-regulated expression and 419 genes with down-regulated expression. The expression levels of multiple genes involving in cell proliferation, differentiation, apoptosis and migration had significant changes. MMP2 gene had high expression in skin tissue of rex rabbits in dense fur group, which was 8. 195 times of gene expression in sparse fur group ; CCNA2 gene had low expression in skin tissue of rex rabbit in dense fur group, which was 0. 143 times of gene expression in spaarse fur group. [ Conclusion ] The results provide the theoretical basis and research direction for early breeding of rex rabbit in practical production.

Thickness Method for Measuring Hair Density of Rex Rabbit

[Objective] The paper was to characterize hair density by changes in hair thickness under certain pressure.[Method] Tile effects of weight of thickness tester and wafer urea at the hottom of presser foot on measurement results were studied, and the optimal measuring weight and wafer diameter was determined. The measurement results of hair thickness under the ahove condition were compared with the results of manual counting. Meanwhile, the effects of hair length and hair fineness on hair density were analyzed.[Result] The hair density obtained by manual count- ing had consistent change trend with the hair thickness measured under certain conditions. If the length and fineness of hairs were introduced for modification, the correlation between hair thickness and hair density would be better. There were little changes in hair length and finelless of rex rabbit, and their effects on hair thickness could be ignored under general condition. [Conclusion] It is completely feasible to characterize hair den- sity of rex rabbit by hair thickness under pressure.

Phenotypic and Genetic Characteristics of a Bordetella hinzii Isolated from a Rex Rabbit

A Bordetella hinzii strain, isolated from the lung of a dead breast-feeding infant rex rabbit with a respiratory infection, was used as study object to investigate its phenotypic and genetic characteristics. The strain could grow on MacConkey agar and was gram-negative, oxidase-positive, catalase-positive, short rodshaped, and it can produce alkali from malonate. Its 6S rRNA sequence was partially identical with B. hinzii （AF177667）. Animal experiments revealed nasal mucous hyperemia, tracheal congestion and bronchopneumonia in 28-day old rex rabbits. To sum up, this Bordetella hinzii isolate was deemed as a novel causative agent of respiratory disease in rex rabbit.

Pathogenicity of Escherichia coli O_(123) from Rex Rabbit on White Mice

[Objective]The paper was to analyze the pathogenesis of Escherichia coli O123 from rex rabbit. [Method]E. coli O123 isolated from rabbit liver with diarrhea symptom in scale rex rabbit farm was intraperitoneally injected into 18- 22 g Kunming mice,and its pathogenicity was determined by clinical symptoms and pathological examination. [Result]When the inoculation concentration was about 8. 5 × 107 CFU /mL,Kunming mice appeared the clinical symptoms of drooping spirit,diarrhea and gathering,and the mortality reached 50%. Anatomical examination found that intestinal wall was thinning and intestinal mucosa was bleeding. [Conclusion]E. coli from rex rabbit has strong pathogenicity,and establishing animal model with Kunming mice to study its pathogenesis is of great reference significance for diagnosis and prevention of E. coli disease of rex rabbit.

Effects of Different Feed Additives on Fur Production Performance of Rex Rabbit

[ Objectivel To investigate the effects of three different levels of feed additives on fur production performance of Rex rabbit. [ Method] A total of 60 healthy American strain Rex rabbits at the age of 60 d （female：male =1：1 ） were randomly divided into group I, group II and group III. The Rex rabbits in the group I were fed basal diet containing nutritional substances; those in the group II were fed basal diet containing nutdtionai substances and Chinese herbal additive; and those in the group III were fed basal diet containing nutritional substances, Chinese herbal additive and enzyme. The trial lasted for 100 d. After slaughtering, the fur area, fur thickness, wool density, wool fineness and coarse wool rate were determined. [Result] The fur production performance of group III was significantly higher than that of group I （ P 〈 0.05）. There was no significant difference between group III and group II. [ Conclusion] Supplementing Chinese herbal additive and enzyme in diet can improve the fur production performance of Rex rabbit.