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Simple Summary: The aim of this study is to provide information about the Pasteurella multocida strains that are responsible for pasteurellosis in rabbits. A total of 114 strains responsible for different lesions in rabbits from industrial farms were investigated. In detail, the serogroup belonging to and the presence of 15 virulence-associated genes were investigated using PCR (polymerase chain reaction) protocols. The tested strains belonged to serogroups A, D, and F. Type A was the most frequently identified and it was prevalently found in strains responsible for rhinitis and pneumonia. Type D was the prevalent capsular type of strains responsible for metritis, while F was identified in strains detected from otitis, mastitis, subcutaneous abscesses, and septicaemia. Among the virulence-associated genes, sodC was found in all tested strains. Gene pfhA was more frequently found in strains belonging to type A than in type D and it was prevalently found in strains responsible for respiratory lesions. In addition, it was found in all F strains, suggesting a strong relationship between pfhA and this capsular type. Conversely, gene tadD was rarely found in strains belonging to capsular type F. Gene fur occurred more frequently in strains belonging to type D and involved with rhinitis. Gene hgbB was detected prevalently in strains responsible for metritis. Additionally, based on the results, the presence of more than 8 virulence-associated genes in the strains seems to increase the risk of the occurrence of severe lesions in the affected rabbits. Nevertheless, the detection of some strains responsible only for rhinitis which were equipped with 10 and 11 virulence-associated genes, seems to emphasise the importance of a gene's expression rather than its presence in strains. Pasteurellosis, a disease caused by Pasteurella multocida, is responsible for economic losses in rabbit industrial farms due to rhinitis, conjunctivitis, pneumonia, metritis, mastitis, orchitis, subcutaneous abscesses, otitis, encephalitis, and septicaemic forms. Although the occurrence of the disease is conditioned by predisposing factors that affect the rabbit immune response, the strains of P. multocida involved in the infection may have a different pathogenic ability. Therefore, typing of strains spread among the rabbits is important to assess their pathogenic potential. The aim of this study is to investigate the P. multocida strains responsible for disease in rabbit industrial farms. A total of 114 strains identified from different lesions were serotyped. Additionally, the presence of virulence-associated genes was investigated using three PCR (polymerase chain reaction) protocols. Capsular type A was prevalently found in strains from respiratory lesions while types D and F in those from metritis, mastitis, and other lesions. Different associations between some virulence-associated genes and both capsular type and lesions found in rabbits were detected. The presence of 8 virulence-associated genes seems to increase the occurrence of metritis. In addition, strains belonging to capsular type A and responsible for respiratory disorders especially, were found equipped with 10 and 11 virulence-associated genes. Nevertheless, the presence of strains responsible only for rhinitis was also detected among the latter, suggesting that the pathogenic ability of the bacteria depends on the expression rather than the presence of a gene. [ABSTRACT FROM AUTHOR]

Simple Summary: In the rabbit species, the use of frozen semen could play a twofold role; on the one hand, it could bring many benefits to commercial breeding operations that rely on artificial insemination, and on the other hand, it would enable the conservation of biodiversity through the establishment of semen cryobanks. One of the less explored aspects of cryopreserving rabbit semen involves establishing the ideal sperm concentration in straws. Achieving this goal is crucial for minimizing the variability in outcomes and accurately determining the number of sperm delivered during artificial insemination procedures. This study sought to determine the ideal sperm concentration in straws for cryopreserving rabbit semen, with the broader goal of improving and standardizing the freezing protocol developed by our research group over the past decade. Our study provided a comprehensive analysis of how different sperm concentrations within straws (ranging from 15 to 75 million sperm) influenced the critical stages of the cryopreservation process, starting from initial dilution with the extender, through to cooling and equilibration, and culminating in the thawing phase. This investigation shed light on the role of the sperm concentration when determining the overall success of rabbit semen cryopreservation. This study aimed to investigate the impact of sperm concentrations on the in vitro quality of cryopreserved rabbit semen. The semen pools (n = 8, from 80 donors) were split into five aliquots with final sperm concentrations of 15, 25, 35, 55, and 75 × 106 per straw. The sperm motility parameters (CASA system) and membrane integrity (flow cytometric analysis) were both evaluated at various stages of the cryopreservation process: fresh semen dilution, cooling, equilibration, and immediately after and 30 min post-thawing. The results indicated the significant influence of the sperm concentration on the total motility (TM) and progressive motility (PM), with a consistent decline in all sperm variables over the time points. Notably, the semen with a final concentration of 15 × 106 exhibited a higher TM and PM after cooling and equilibration. The post-thawing quality (TM, PM) was higher (p < 0.05) in the mid-range sperm concentrations of 25 × 106 (49.9% and 19.7%) and 35 × 106 (46.2% and 19.7%) compared to the other concentrations. This study demonstrated that the sperm concentration per straw played a significant role in specific phases of the cryopreservation process. These findings contribute valuable insights for refining and standardizing the cryopreservation protocol for rabbit semen, emphasizing the importance of the sperm concentration. [ABSTRACT FROM AUTHOR]

Objective: The growing consumers' interest on animal welfare has raised the request of products obtained by alternative rearing systems. The present study was conducted to assess the influence of housing system on gut and muscle morphology and on microbial load in rabbits reared under free-range (FR) and cage system (CS). Methods: A total of forty weaned (35 days of age) male Italian White breed rabbits were allotted according to the rearing system, and at 91 days of age were randomly selected and slaughtered for the morphological evaluation of tissue from duodenum and longissimus lumborum. Morphometric analysis of the villus height, villus width, crypt depth, villus height/crypt depth ratio, and villus surface was performed. The microbial loads on hind muscle was determined by total mesophilic aerobic count (TMAC), Escherichia coli and Enterobacteriaceae; whereas, total anaerobic bacteria count (TABC) and TMAC, E. coli and Enterobacteriaceae was determined on caecal content. Results: Rearing system did not interfere with the duodenum and muscle histomorphology in both rabbit groups. Similarly, microbial load of caecal content showed no significant differences on the TABC and TMAC. Conversely, significant difference was found for E. coli strains in caecal content, with the lower counts in FR compared to CS rabbits (p<0.01). Microbiological assay of muscle revealed significant lower TMAC in FR vs CS rabbits (p< 0.05). All rabbit meat samples were negative for E. Coli and Enterobacteriaceae. Conclusion: Free-range could be considered a possible alternative and sustainable rearing system in rabbits to preserve gut environment and muscle quality. [ABSTRACT FROM AUTHOR]

Pasteurellosis, a disease caused by Pasteurella multocida , is responsible for economic losses in rabbit industrial farms due to rhinitis, conjunctivitis, pneumonia, metritis, mastitis, orchitis, subcutaneous abscesses, otitis, encephalitis, and septicaemic forms. Although the occurrence of the disease is conditioned by predisposing factors that affect the rabbit immune response, the strains of P. multocida involved in the infection may have a different pathogenic ability. Therefore, typing of strains spread among the rabbits is important to assess their pathogenic potential. The aim of this study is to investigate the P. multocida strains responsible for disease in rabbit industrial farms. A total of 114 strains identified from different lesions were serotyped. Additionally, the presence of virulence-associated genes was investigated using three PCR (polymerase chain reaction) protocols. Capsular type A was prevalently found in strains from respiratory lesions while types D and F in those from metritis, mastitis, and other lesions. Different associations between some virulence-associated genes and both capsular type and lesions found in rabbits were detected. The presence of 8 virulence-associated genes seems to increase the occurrence of metritis. In addition, strains belonging to capsular type A and responsible for respiratory disorders especially, were found equipped with 10 and 11 virulence-associated genes. Nevertheless, the presence of strains responsible only for rhinitis was also detected among the latter, suggesting that the pathogenic ability of the bacteria depends on the expression rather than the presence of a gene.