World Rabbit Science

Sample preparation and storage effects on fatty acid profile of rabbit Longissimus thoracis et lumborum muscle

2022-03-08T11:08:32+01:00

Twenty-five Pannon White male rabbits reared and fed in similar conditions were slaughtered at 11 weeks of age. The longissimus thoracis et lumborum muscles (LTL; right and left) were removed at 24 h post-mortem and allocated to four sampling/storage treatments: the left side of LTL muscle was divided in half perpendicularly, with the posterior portion being analysed within one day (fresh), and the anterior portion vacuum packaged and stored for 1 mo at –20°C (whole-frozen); the right LTL side was ground with half of the product vacuum packaged and frozen for 1 mo at –20°C (ground-frozen), whereas the other half was freeze-dried, vacuum packaged, and stored for 1 mo at 4°C (freeze-dried refrigerated). Treatments impacted percentages of total saturated (P<0.01), monounsaturated (P<0.05), and polyunsaturated fatty acids (P<0.001), whole-frozen treatment affecting the most the fatty acids profile of the meat. Method of preparation and storage of meat samples before performing fatty acid analysis had an impact on the percentage of specific fatty acids, which could render the precision of study-to-study comparisons less reliable.

Partial diallel cross for assessing genetic merit of local rabbit breed

2022-06-10T10:33:30+02:00

This study was carried out to estimate general combining ability (GCA) and specific combining ability (SCA) of pre-and post-weaning traits from a partial diallel cross in three rabbit breeds: Local rabbit (L), Flemish Giant (F), and Rex (R). Body weight at 0 (BW₀), 30 (BW₃₀), 42 (BW₄₂), and 63 (BW₆₃) days of age, average daily gains from 0 to 30 d of age (ADG_0-30), from 30 to 42 d of age (ADG_30-42), from 42 to 63 d of age (ADG_42-63), and from 30 to 63 d of age (ADG_30-63), litter size at birth (LS₀) and at weaning (LS₄₂), and mortality at weaning (MR₄₂) were studied in crossing LL, FF, RR, LF, LR, and FR. Local breed had the highest GCA for BW₀, BW₃₀, BW₄₂, and average daily gain before weaning (ADG_0-30, and ADG_30-42) compared to Flemish Giant and Rex, while GCA of Local breed for average daily gain after weaning (ADG_42-63), litter size (LS₀, and LS₄₂), and mortality (MR₄₂) was higher than for Rex and similar to that of Flemish Giant. Crossing LF and LR showed higher SCA for BW₃₀, BW₄₂, BW₆₃, ADG_0-30, ADG_42-63 and ADG_30-63 than FR. In conclusion, based on GCA and SCA, the Indonesian Local breed has a high genetic potential in the crossing with Flemish Giant and Rex breeds.

Mitochondrial D-loop sequences and haplotypes diversity in Egyptian rabbit breeds

2022-05-20T10:03:48+02:00

Rabbit breeds in Egypt are local and adapted foreign breeds that have been imported since the middle of the last century. Stressful environmental conditions including climatic changes, exposure to diseases and breeding selection have an influence on how gene flow has shaped the genetic diversity of the breeds. Mitochondrial DNA D-loop is a genetic marker used to trace the geographic distribution of genetic variation for the investigation of expansions, migrations and other gene flow patterns. The study aimed to determine the genetic diversity of the mitochondrial DNA D-loop (mtDNA D-loop) in Black Baladi, Red Baladi, Gabali, APRI line and New Zealand breeds to gather the scientific data required to create a proper conservation and sustainable management plan. Blood samples were taken from animals unrelated to each other. A 332-bp of mtDNA D-loop was successfully amplified and alignment sequences were deposited in the GenBank database. The results detected six haplotypes in the five breeds. Haplotype diversity within individual breeds varied from 0 (Red Baladi) to 0.551±0.114 (Gabali). The nucleotide diversity (π) value was relatively low (0.001-0.006), with greater values in APRI and New Zealand. Pairwise distances between breeds yielded varying values ranging from 0 to 0.254, and the values between the Red Baladi and other breeds were comparatively high, with pairwise distances from 0.172 to 0.254. The phylogenetic analysis involved 74 nucleotide sequences of the Egyptian rabbit and thirty-one sequences retrieved from GenBank of the reference samples of different haplogroups. The results of the phylogenetic analysis correlated to the reference mtDNA GenBank database showed that the five Egyptian rabbit breeds were grouped into haplotypes A, B and K. The results of the genetic diversity using mtDNA shed light on the importance of the local breed’s genetic diversity information and revealed unique mtDNA haplotypes, which is an important finding for breeding strategies designed to conserve genetic variants and provide sustainable management.

Characterisation and functional analysis of the WIF1 gene and its role in hair follicle growth and development of the Angora rabbit

2022-06-28T14:51:54+02:00

Growth and development of hair follicles (HF) is a complex and dynamic process in most mammals. As HF growth and development regulate rabbit wool yield, exploring the role of genes involved in HF growth and development may be relevant. In this study, the coding sequence of the Angora rabbit (Oryctolagus cuniculus) WIF1 gene was cloned. The length of the coding region sequence was found to be 1140 bp, which encodes 379 amino acids. Bioinformatics analysis indicated that the WIF1 protein was unstable, hydrophilic and located in the extracellular region, contained a putative signal peptide and exhibited a high homology in different mammals. Moreover, WIF1 was significantly downregulated in the high wool production in the Angora rabbit group. Overexpression and knockdown studies revealed that WIF1 regulates HF growth and development-related genes and proteins, such as LEF1 and CCND1. WIF1 activated β-catenin/TCF transcriptional activity, promoted cell apoptosis and inhibited cellular proliferation. These results indicate that WIF1 might be important for HF development. This study, therefore, provides a theoretical foundation for investigating WIF1 in HF growth and development.

Influence of alpha linolenic acid on the motility, viability, antioxidant activity and fertility of frozen-thawed New Zealand white rabbit buck semen

2022-03-16T14:41:00+01:00

Freezing and thawing processes result in production and accumulation of high concentrations of reactive oxygen species that are detrimental to spermatozoal motility and fertility. Therefore, supplementation of exogenous source of antioxidants to freezing diluent is crucial. The aim of the present study was to investigate for the first time whether supplementation of semen diluent with alpha linolenic acid (ALA) can improve motility, viability, membrane integrity, antioxidant status and fertility of post-thaw rabbit spermatozoa. Semen was collected and pooled from fifteen New Zealand white rabbit bucks. Semen samples were diluted with a tris-citrate-glucose (TCG) extender supplemented with ALA (0, 50, 75 and 100 μmol). Then, extended rabbit semen was cooled at 5°C and cryopreserved in liquid nitrogen. After thawing, spermatozoal quality parameters (individual motility %, viability %, osmotic resistance %, and acrosome integrity %), antioxidant activity (SOD, CAT, and GSH activities), lipid peroxidation (malondialdehyde) and fertility (conception and kindling rates) were evaluated. Results revealed that supplementation of rabbit semen extender with 50 μmol ALA significantly (P<0.05) increased spermatozoal characteristics including motility (56.54%), viability (60.01%), acrosome status (72.66%) and membrane integrity (59.13%). The activity of semen antioxidant enzymes (SOD, CAT, and GSH) showed a significant improvement with a marked decrease in lipid peroxidation. Moreover, the conception (73.30%) and kindling (70.00%) rates were significantly (P<0.05) higher in does inseminated with thawed semen treated with 50 μmol ALA in comparison with other concentrations (0, 75 and 100 μmol). In summary, supplementation of rabbit semen extender with 50 μmol ALA improved motility, viability, membrane integrity, acrosome integrity, antioxidant enzymes activity and fertility of post-thaw rabbit spermatozoa. Our findings suggested that higher concentrations of ALA are detrimental to post-thaw characteristics of New Zealand white rabbit buck spermatozoa. To achieve better results, the semen freezing extender should be supplemented with ALA at lower concentrations, especially 50 μmol.

Cryopreservation of rabbit semen: impacts of permeable and non-permeable mixture of cryoprotectant, male group individuality, freezing rate, semen package size and antioxidant bovine serum albumin on rabbit semen freezability

2022-05-02T19:48:49+02:00

In the present study, three experiments were designed to identify the most appropriate technique for freezing rabbit semen. Experiment 1 aimed to determine the optimal levels of dimethyl sulfoxide (DMSO) contents in freezing medium and their effects on individual bucks. Semen ejaculates for each buck (n=15 bucks) were mixed and split into three portions for extension with a freezing medium containing varying concentrations of DMSO (0.75, 1.0, and 1.4 M). Diluted semen samples were packaged in 0.25 mL straws and suspended above liquid nitrogen (LN) for 10 min, then dipped in LN. A few days after freezing, post-thaw semen evaluation was assessed, and according to the results, six bucks and an extender containing 0.75 M of DMSO were used for experiments 2 and 3. In experiment 2, the pooled semen from 6 bucks was divided into two portions for packaging in two straw sizes (0.25 and 0.50 mL). Each straw size was divided into five groups and suspended at different heights above LN (2, 4, 6, 8, and 10 cm) for 10 minutes before being preserved in LN. In experiment 3, the pooled semen was divided into four portions for dilution with freezing medium containing different concentrations of bovine serum albumin (BSA; 0, 2.5, 5.0, and 7.5 mg/mL). Semen samples were packaged in a 0.50 mL straw and suspended 10 min, 4 cm above LN for freezing. Pre-freezing and post-thawing, semen samples were evaluated for semen quality. Results showed that the extender containing 0.75 M DMSO had higher significant values for post-thaw sperm motility, longevity, acrosome integrity and sperm plasma membrane permeability. Bucks’ individuality had significant effects on post-thaw motility, acrosome and sperm plasma membrane integrity. A significant interaction was recorded between DMSO concentrations and bucks’ individuality on sperm longevity. Semen package sizes had no significant effects on the evaluated parameters. Semen was frozen at 2 and 4 cm above LN had significantly better post-thaw quality. BSA at concentrations 5 and 7.5 mg/mL improved recovery rates of acrosome integrity and sperm membrane permeability. DMSO 0.75 M and freezing 4 cm above LN seem to be more adequate for rabbit semen cryopreservation. The appropriate level of DMSO differs between bucks, as the post-thaw sperm longevity is affected. BSA enhanced acrosome and sperm membrane integrity. Results obtained will need further investigation to be confirmed in the field.

Abstracts of the 46th Symposium on Cuniculture, ASESCU

2022-06-06T20:12:46+02:00

The 46^th Congress of the Spanish Association of Cuniculture (ASESCU) was held in Pineda de Mar (Barcelona, Catalonia, Spain) from 1^st to 2^nd June 2022, hosted by the Institute of Agrifood Research and Technology (IRTA) and the Department of Climate Action, Food and Rural Agenda of the Government of Catalonia. Four main guest lectures were given. The first explained the trends in the meat products market and the implications for the rabbit sector. Another presented an overview of rabbit farming in Catalonia. Moreover, another talk addressed the question of how much a rabbit farm pollutes. Finally, a fourth talk was addressed to the prudent use of antibiotics in rabbit farming in a context of reducing the use of antimicrobials. A round table was held on the demands of European legislation and citizens in terms of rabbit housing and welfare, with the participation of experts from Belgium, Italy and Spain. In addition, a total of 26 communications were presented in working sessions (genetics, nutrition, reproduction, and pathology and welfare) as oral communications and posters. The meeting was attended by almost 140 participants from several European and American countries. Abstracts of the contributions presented are reported below.