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 (FST) 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.

The present study aimed to examine the impact of dietary supplementation of Boswellia serrata (BS) (frankincense) resin on growth and carcass traits, blood hematology, serum metabolites and cecal microbiota of growing rabbits. One hundred New Zealand White (NZW) growing male rabbits (6-weeks old) were divided randomly into five groups using different levels of BS (0.00, 0.25, 0.50, 0.75, 1.00 g/kg diet, respectively). When compared to the control diet, daily body weight gain (BWG) and feed conversion ratio (FCR) of rabbits fed BS enriched-diets were improved, while feed intake was significantly decreased. A gradual depression (P < 0.01) in serum triglycerides (TG), total cholesterol (TC) and low density lipoproteins (LDL) were observed with increasing BS level the in diet. Total bacteria count, E. coli and salmonella populations were lower (P < 0.05) in rabbit groups fed diet enriched with BS than that of the control group. Based on these findings, the dietary supplementation of Boswellia serrata enhanced growth, feed efficiency, anti-oxidant status, and minimize cecal pathogenic bacteria in rabbits.

The aim of this study was to investigate the effect of initial cooling time at 5°C during semen cryopreservation on post-thaw quality and reproductive performance of rabbit semen. Pooled semen samples (n = 6) were divided into two subsamples and cooled at 5°C for 45 or 90 min. After cooling, the semen samples were diluted to a ratio of 1:1 (v:v) with a freezing extender composed of Tris-citrate-glucose (TCG) containing 16% of dimethylsulfoxide and 0.1 mol/L sucrose. The semen was subsequently loaded in 0.25 ml straws, equilibrated at 5°C and frozen in liquid nitrogen vapor. After thawing, sperm motility, viability, osmotic resistance, acrosome and DNA integrity were assessed. Our results indicate that the longer cooling time, that is, 90 min before cryopreservation significantly improves sperm post-thaw viability, motility and fertility. In fact, reproductive performances obtained with semen frozen after a 90 min cooling time were similar to those produced by fresh semen insemination. Hence, the present research provides an effective freezing protocol for rabbit semen that will allow for the creation of a sperm cryobank for the conservation of Italian rabbit genetic resources, as well as the use of frozen semen doses in commercial farms.

Runs of homozygosity (ROH) are defined as long stretches of DNA homozygous at each polymorphic position. The proportion of genome covered by ROH and their length are indicators of the level and origin of inbreeding. In this study, we analysed SNP chip datasets (obtained using the Axiom OrcunSNP Array) of a total of 702 rabbits from 12 fancy breeds and four meat breeds to identify ROH with different approaches and calculate several genomic inbreeding parameters.The highest average number of ROH per animal was detected in Belgian Hare (~150) and the lowest in Italian Silver (~106). The average length of ROH ranged from 4.001 ± 0.556 Mb in Italian White to 6.268 ± 1.355 Mb in Ermine. The same two breeds had the lowest (427.9 ± 86.4 Mb, Italian White) and the highest (921.3 ± 179.8 Mb, Ermine) average values of the sum of all ROH segments. More fancy breeds had a higher level of genomic inbreeding (as defined by ROH) than meat breeds. Several ROH islands contain genes involved in body size, body length, pigmentation processes, carcass traits, growth, and reproduction traits (e.

Summary In the European rabbit (Oryctolagus cuniculus), a polytocous livestock species, the number of teats indirectly impacts the doe reproduction efficiency and, in turn, the sustainable production of rabbit meat. In this study, we carried out a genome‐wide association study (GWAS) for the total number of teats in 247 Italian White does included in the Italian White rabbit breed selection program, by applying a selective genotyping approach. Does had either 8 (n = 121) or 10 teats (n = 126). All rabbits were genotyped with the Affymetrix Axiom OrcunSNP Array. Genomic data from the two extreme groups of rabbits were also analysed with the single‐marker fixation index statistic and combined with the GWAS results. The GWAS identified 50 significant SNPs and the fixation index analysis identified a total of 20 SNPs that trespassed the 99.98th percentile threshold, 19 of which confirmed the GWAS results. The most significant SNP (P = 4.31 × 10−11) was located on OCU1, close to the NUDT2 gene, a breast carcinoma cells proliferation promoter. Another significant SNP identified as candidate gene NR6A1, which is well known to play an important role in affecting the correlated number of vertebrae in pigs. Other significant markers were close to candidate genes involved in determining body length in mice. Markers associated with increased number of teats could be included in selection programmes to speed up the improvement for this trait in rabbit lines that need to increase maternal performances.

Effects of dietary supplementation of verbascoside and lycopene, alone and in combination, on some blood parameters, plasma oxidative status and meat quality traits in intensively reared rabbits were investigated. The test lasted 60 days and was conducted on 200 weaned‐rabbits, divided into four groups of 50 animals each (5 animals each cage × 10 repetitions). The control group (CON) received a fattening feed without any feed supplements, whereas the experimental groups received the following: the first, an integration in 22 g of PLX®23 (Lippia citriodora extract; VB group) per ton of feed; the second, an integration in 100 g of LycoBeads® (Solanum lycopersicum extract; LIC group) per ton of feed; and the third, an integration of both feed supplements in combination at the same doses (LIC+VB group). The dietary supplementation with Lippia citriodora and Solanum lycopersicum resulted in an improvement of the blood lipid profile, oxidative plasma markers, and hepatic and renal activity of treated growing rabbits. Feed additives also produced meat with a lower content in SFA and an increased PUFA content, and inhibited the lipid oxidation improving the oxidative stability of rabbit meat. The dietary supplementation, even reporting no effects on productive parameters and carcass yield, showed an improvement on several blood parameters, as indicator of animal welfare, and on quality and healthy meat markers.

AbstractThis study has been designed to optimize the semen freezing protocol in rabbits, in this regard we compared a Tris-citrate-glucose (TCG) extender with a commercial one (Cortalap®), that to the best of our knowledge has never been used up to now on the in vitro freezability and fertilizing ability of cryopreserved rabbit semen. Two different inseminating semen doses were considered. Five pooled semen samples were divided into two subsamples and each of them were diluted to a ratio 1:1 (v:v) with a freezing extender composed of TCG or Cortalap® containing 16% of dimethylsulfoxide and 0.1 mol/L of sucrose. The extended semen was filled into 0.25 mL plastic straws and frozen above a liquid nitrogen surface. After thawing (50°C/10 seconds) we determined sperm motility, viability, membrane functionality, acrosome and DNA integrity. Our results showed that the Cortalap® extender significantly improved the in vitro post-thaw sperm quality, in comparison to TCG. When we compared the extenders in vivo, no significant differences in the reproductive performances were observed independently by inseminating doses used. In this study we demonstrated that Cortalap® extender can be used as an alternative to TCG. Thus, the Cortalap® being a ready to use extender, implies a reduction of time, mistakes and microbial contaminations during its preparation. This discovery results as significant because it provides beyond an important contribution to the creation of the first Italian semen cryobank of rabbit breeds and also for livestock rabbit farms based on artificial insemination (AI) program.

Title of the manuscript: Evaluating productive performance, meat quality and oxidation products of Italian White breed rabbits under free-range and cage rearing system ABSTRACT Objective: Free-range systems have been increasingly available to the consumer due to increased demand for more sustainable meat-products. In the current study, it was explored the effect of free-range (FR) and cage system (CS) 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 treatmentgroup). 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 of 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, free-range system could be suggested as a substitute for conventional caged system because of free-range system preserved rabbit meat from oxidation.