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Background Domestication of the rabbit ( Oryctolagus cuniculus ) has led to a multi-purpose species that includes many breeds and lines with a broad phenotypic diversity, mainly for external traits (e.g. coat colours and patterns, fur structure, and morphometric traits) that are valued by fancy rabbit breeders. As a consequence of this human-driven selection, distinct signatures are expected to be present in the rabbit genome, defined as signatures of selection or selective sweeps. Here, we investigated the genome of three Italian commercial meat rabbit breeds (Italian Silver, Italian Spotted and Italian White) and 12 fancy rabbit breeds (Belgian Hare, Burgundy Fawn, Champagne d’Argent, Checkered Giant, Coloured Dwarf, Dwarf Lop, Ermine, Giant Grey, Giant White, Rex, Rhinelander and Thuringian) by using high-density single nucleotide polymorphism data. Signatures of selection were identified based on the fixation index (F ST ) statistic with different approaches, including single-breed and group-based methods, the latter comparing breeds that are grouped based on external traits (different coat colours and body sizes) and types (i.e. meat vs. fancy breeds). Results We identified 309 genomic regions that contained signatures of selection and that included genes that are known to affect coat colour ( ASIP , MC1R and TYR ), coat structure ( LIPH ), and body size ( LCORL / NCAPG , COL11A1 and HOXD ) in rabbits and that characterize the investigated breeds. Their identification proves the suitability of the applied methodologies for capturing recent selection events. Other regions included novel candidate genes that might contribute to the phenotypic variation among the analyzed breeds, including genes for pigmentation-related traits ( EDNRA , EDNRB , MITF and OCA2 ) and body size, with a strong candidate for dwarfism in rabbit ( COL2A1 ). Conclusions We report a genome-wide view of genetic loci that underlie the main phenotypic differences in the analyzed rabbit breeds, which can be useful to understand the shift from the domestication process to the development of breeds in O. cuniculus . These results enhance our knowledge about the major genetic loci involved in rabbit external traits and add novel information to understand the complexity of the genetic architecture underlying body size in mammals.

Objective: This paper aimed to evaluate the effects of a multi-strain probiotic (MS-Prob) as natural feed additives on the productive performance, blood parameters, antioxidant defence, caecal short-chain fatty acid profile as well as the effectiveness on the intestinal morphology and on the equilibrium modification of caecal microbiota of growing rabbits.Methods: Eighty-six-week-old Italian White rabbits were assigned into two dietary groups: the control group was fed without any additive, while the test group received a diet supplemented with a MS-Prob (Slab51) at a dosage of 250 mg/kg diet. The feeding trial lasted up to 12 weeks of age.Results: Rabbits MS-Prob diet had significantly higher daily and final body weight recording also the best of feed efficiency compared to control group. Rabbits in MS-Prob group showed improved slaughter weight and carcass dressing yield. No significant effect was found on meat protein, lipids and ash contents. Serum total cholesterol, low-density lipoprotein, high-density lipoprotein and triglycerides decreased significantly in rabbits fed the test-diet. In rabbits fed MS-Prob, the activity of glutathione peroxidase, glutathione S-transferase, catalase and superoxide dismutase increased significantly, whereas the level of thiobarbituric acid-reactive substance decreased significantly. Caecal pH, ammonia-N and total volatile fatty acids (VFAs) were not significantly influenced by dietary treatments. Conversely, VFAs molar proportions were statistically affected by diets, with higher acetic and butyric acid concentrations in caecum of rabbits fed MS-Prob. Feeding of MS-Prob reduced harmful bacterial growth (Escherichia coli, Bacillus spp., Clostridium spp.) while promoting beneficial bacteria (Lactobacillus spp., Bacteroides spp.). Moreover, MS-Prob positively influences rabbit gut histomorphology, showing higher villus height, villus width, and crypt depth.Conclusion: This study indicated that MS-Prob (Slab51) supplementation stimulated the performance of growing rabbits and positively affected blood serum parameters, intestinal morphology, and caecal environment and microbiota.

The cryopreservation of rabbit semen is a valuable strategy for genetic resource preservation and efficient artificial insemination, but outcomes remain inconsistent, partly due to variations in sperm concentration per dose. This study aimed to evaluate the in vivo effects of different sperm concentrations (15, 25, 35, 55, and 75 million per straw) on fertility, prolificacy, and offspring growth in nulliparous and multiparous does. A total of 384 rabbit females were inseminated using frozen–thawed semen, and their reproductive performance was compared with fresh semen. Fertility and kindling rates varied with sperm concentration and parity: nulliparous does showed the highest fertility at 15 million sperm/straw (84.4%), while multiparous does reached peak values at 25–55 million/straw (78.1–81.3%). Litter size and live-born kits were consistently higher in multiparous than in nulliparous does. Offspring body weight at 19 and 60 days was influenced by both sperm concentration and maternal parity, with better growth generally observed in multiparous groups. Weaning success remained high across all groups. Our results indicate that sperm concentrations ranging from 15 to 35 × 106/straw are the most suitable for cryopreservation, as they maintain high fertility, prolificacy, and offspring growth, comparable to fresh semen. These results confirm that optimizing sperm concentration during cryopreservation improves reproductive efficiency and that tailoring insemination strategies to the physiological status of the female enhances outcomes. The results provide useful recommendations for improving cryopreservation techniques in rabbit breeding programs.

Objective: Free-range systems have been increasingly available to the consumer due to increased demand for more sustainable meat-products. In the current study, the effect of free-range (FR) and cage system (CS) was explored on growth performance, meat quality and oxidation products in Italian White breed rabbits during the growing-fattening phase (5 to 13 weeks of age).Methods: Forty rabbits were randomly allotted to two treatment groups according to the rearing system, and each treatment group was replicated five times with four subjects in each replicate (20 rabbits per treatment-group). All rabbits fed the same diet as pelleted, and under FR system, no additional feeds were available to animals.Results: Rearing system had significant effect on rabbit growth performance, where CS group resulted in higher final body weight (p<0.045) and gain (p<0.029) and better feed efficiency (p<0.025) compared to FR rabbits. Most carcass traits were not affected by rearing system; however, a reduction of abdominal fat content (p<0.015) and meat lipids (p<0.034) was observed in FR rabbits. Rearing system had no effects on meat fatty acid profile, whereas meat from FR rabbits resulted less susceptible to lipid and protein oxidation compared to caged animals.Conclusion: In overall, FR system could be suggested as a substitute for conventional caged system because of FR system preserved rabbit meat from oxidation.

Group A rotaviruses (RVAs) are a major cause of acute dehydrating diarrhea in infants and young animals worldwide. In rabbits, RVAs are associated with enteric disease, likely in combination with other pathogens. We report the identification and characterization of a lapine RVA strain in an Italian rabbit breeding farm. Increased mortality rates associated with enteric symptoms were reported in the facility in post-weaning rabbits around 40 days of age. By quantitative RT-PCR, an RVA strain was identified in the intestinal contents of deceased rabbits. A PCR-based enrichment protocol coupled with Nanopore sequencing allowed the reconstruction of the nearly complete genome of a rabbit RVA strain, Rabbit-wt/ITA/36-9/2022/G3P[14], with a genotype constellation (G3-P[14]-I2-R2-C2-M3-A9-N2-T6-E5-H3) conserved among lapine RVAs. Each of the 11 gene segments displayed high nucleotide identity and phylogenetic clustering with lapine rotavirus strains, as well as two Belgian human G3P[14] strains, which had been shown to have a zoonotic (lapine) origin. However, the NSP2 gene of strain 36-9 clustered closer with a group of rare human G3P[9] strains, suggesting a common path during their evolution. Gathering sequence data on animal RVAs is pivotal to reconstructing the history of homologous and heterologous RVAs in various mammals, including humans.

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.

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.

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.

Among the goals of global environmental policies, one is to achieve a critical rethinking of the agro-industrial production chain aimed at enhancing its sustainability and resilience while addressing its environmental impact. Lentils are widespread worldwide and are consumed as part of traditional dishes, and their health-promoting benefits are currently well recognized. Their industrial processing for human consumption implies the generation of different by-products which can be used as promising alternative feedstuff. Calling for the future sustainable development of rabbit farming, the present study questions the dietary inclusion of red lentil screenings (RLS) as an upcycling strategy for this by-product, as well as to ease the challenges faced by the rabbit-farming system. A total of 120 male Bianca Italiana breed growing rabbits aged 42 days were allotted to three dietary treatments containing different levels of RLS: 0 (RLS0), 5 (RLS5), or 10% (RLS10), respectively, for 6 weeks. At 84 days (slaughter age), meat, plasma, and intestinal samples were collected. The RLS inclusion showed no adverse effects on growth performance. However, significant differences were found in the meat fatty acid profile, where both RLS5 and RLS10 groups showed reduced C18:0 percentage and higher MUFA content owing to an increase in C18:1 n-9; moreover, RLS5 showed a significant increase in C16:1 trans. On the other hand, only RLS10 recorded a significant reduction in the PUFA total content due to decreased single unsaturated fatty acid (C18:2 n-6; C20:3 n-6; C22:5 n-3). Dietary RLS significantly decreased serum total cholesterol, LDL, and HDL, along with an enhancement of the overall serum antioxidant capacity. The results regarding the rabbit caecal characteristics and microbial population were found to be similar among the groups. However, referring to histomorphometric measurements, both RLS5 and RLS10 groups displayed significant increases in villus height and an improved villus height to crypt depth ratio. In conclusion, up to 10% RLS in the diets rabbits can be considered an effort-effective feeding strategy to modulate rabbit meat fatty acid profiles, to enhance the endogenous antioxidant capacity, and to improve the serum lipid profile and intestinal morphology.

Marrubium vulgare L., commonly known as horehound in Europe, belongs to the Lamiaceae family, one of the most prominent medicinal plant families in the Mediterranean region. Traditionally used in herbal medicine, horehound contains a broad spectrum of bioactive compounds, supporting its potential use as a natural feed additive in animal nutrition. This study evaluated the effects of dietary horehound powder (HP) on growth performance, serum antioxidant status, digestive enzyme activity, intestinal microbial populations, and gut and liver histomorphology in growing rabbits. Eighty weaned male Bianca Italiana rabbits (42 days old) were randomly assigned to two dietary groups for a 6-week feeding trial: a control group fed a basal diet and a treatment group receiving the same diet supplemented with 0.15% HP (1.5 g/kg). At slaughter (84 days of age), samples of meat, blood, liver, and intestinal tissue were collected for analysis. Dietary HP significantly improved final body weight, feed conversion ratio, and carcass yield (P < 0.01), with no notable differences in proximate meat composition. However, meat from HP-fed rabbits showed increased total polyunsaturated fatty acids (PUFAs) (P < 0.05) and n-6 fatty acids (P < 0.01). Serum lipid profiles remained unaffected, while serum antioxidant parameters — total antioxidant capacity (TAC), malondialdehyde (MDA), and superoxide dismutase (SOD )— were significantly enhanced in the HP group. Additionally, HP supplementation increased the activity of duodenal α-amylase, maltase, lipase, and trypsin (P < 0.05). Although caecal morphology did not differ significantly between groups, rabbits receiving HP exhibited higher Lactobacillus spp. counts and reduced Escherichia coli populations. Duodenal histomorphometry showed significant improvements in villus height, crypt depth, and the villus height to crypt depth ratio (P < 0.01). No histological alterations were observed in the liver of rabbits. In conclusion, dietary inclusion of horehound powder positively influenced growth performance, oxidative status, digestive enzyme activity, and intestinal health in rabbits, supporting its use as a functional feed additive in sustainable rabbit production.