Rabbit production and science: the world and Italian scenarios from 1998 to 2018

Social, ethical, environmental, economic and technological aspects of rabbit meat production - A critical review

Rabbit (RM) has become a valuable source of nutrients since the 1970s, helping to transform the European food industry into the largest RM producer in the world. However, the RM industry is experiencing a critical period of ethical imbalance. This trend, described as feed conversion ratio, impacts the environmental and financial performance of RM farms, which could lead to an increase production of industrial waste. In addition, the loss of corporate ethical responsibility and sustainable development by RM-oriented companies has further exacerbated the situation. Our objective was to summarize current trends in the RM industry and markets, highlighting possible strengths and weaknesses. This review shows current approaches in sustainable techniques in RM production processes, ethical issue, environmental and processing responsibility of RM producers, as well as social responsibilities and ethical practices of slaughterhouses and RM producers, sustainable environmental practices of slaughterhouses, technological aspects and safety of RM and social drivers in RM market. The analysis of reviewed literature revealed the potential strategies for sustainable RM production.

Bovine Colostrum Supplementation in Rabbit Diet Modulates Gene Expression of Cytokines, Gut-Vascular Barrier, and Red-Ox-Related Molecules in the Gut Wall

Rabbits, pivotal in the EU as livestock, pets, and experimental animals, face bacterial infection challenges, prompting a quest for alternatives to curb antibiotic resistance. Bovine colostrum (BC), rich in immunoregulatory compounds, antimicrobial peptides, and growth factors, is explored for disease treatment and prevention. This study assesses BC diet supplementation effects on rabbit intestines, examining gene expression. Thirty female New Zealand White rabbits at weaning (35 days) were divided into three experimental groups: control (commercial feed), 2.5% BC, and 5% BC. The diets were administered until slaughtering (81 days). BC-upregulated genes in the jejunum included IL-8, TGF-β, and CTNN-β1 at 5% BC, while PLVAP at 2.5% BC. Antioxidant-related genes (SOD1, GSR) were downregulated in the cecum and colon with 2.5% BC. BC 5% promoted IL-8 in the jejunum, fostering inflammation and immune cell migration. It also induced genes regulating inflammatory responses (TGF-β) and gastrointestinal permeability (CTNN-β1). BC 5% enhanced antioxidant activity in the cecum and colon, but no significant impact on anti-myxo antibody production was observed. These results suggest that BC has significant effects on the rabbit gastrointestinal tract's inflammatory and antioxidant response, but further research is required to fully understand its histological and physiological impact.

Bodybuilders and high-level meat consumers' behavior towards rabbit, beef, chicken, turkey, and lamb meat: A comparative review

In bodybuilders' diets, protein plays a crucial role in supporting muscle growth and repairing damaged muscle tissue. These individuals meet their protein needs by combining dietary sources with supplements. Animal-based proteins are often preferred over plant-based proteins because they are believed to better support muscle protein synthesis. This review explores the meat consumption patterns of bodybuilders and high-level meat consumers, focusing on rabbit, beef, chicken, turkey, and lamb. We describe and compare the types of meat bodybuilders commonly consume and provide an overview of protein supplements, including meat-based options, plant-based alternatives, and whey-based products. Our aim is to gain insight into the dietary preferences of bodybuilders and high-level meat consumers, considering their nutritional requirements and the potential effect on the meat industry. We conducted an extensive search across various databases, including Scopus, Web of Science, PubMed, and Google Scholar. We found that individual choices vary based on factors such as attitudes, trust, taste, texture, nutritional content, ethical considerations, and cultural influences. Nutritional factors, including protein content, amino acid profiles, and fat levels, significantly influence the preferences of bodybuilders and high-level meat consumers. However, it is crucial to maintain a balance by incorporating other essential nutrients such as carbohydrates, healthy fats, vitamins, and minerals to ensure a complete and balanced diet. The findings from this review can inform strategies and product development initiatives tailored to the needs of bodybuilders and discerning meat enthusiasts.

Co-Occurrence of Aflatoxin B1, Zearalenone and Ochratoxin A in Feed and Feed Materials in Central Italy from 2018 to 2022

Mycotoxin contamination of feed and feed materials represent a serious health hazard. This study details the occurrence of aflatoxin B1 (AFB1), zearalenone (ZEN) and ochratoxin A (OTA) in 826 feed and 617 feed material samples, collected in two Italian Regions (Umbria and Marche) from 2018 to 2022 analyzed using a UPLC-FLD platform. The developed method was validated and accredited (ISO/IEC 17025) with satisfactory accuracy and precision data obtained in repeatability and intralaboratory reproducibility conditions. Feed had a higher incidence of contaminated samples (26%) with respect to feed materials (6%). AFB1 was found up to 0.1045 mg/kg in cattle feeds and 0.1234 mg/kg in maize; ZEN was detected up to 6.420 mg/kg in sheep feed while OTA was rarely reported and in lower concentrations (up to 0.085 mg/kg). Co-contamination of at least two mycotoxins was reported in 0.8% of the analyzed samples. The incidence of above maximum content/guidance level samples was 2% for feed and feed materials while almost 3-fold-higher for maize (5.8%) suggesting how mycotoxin contamination can affect some matrices more than others. Obtained data can be useful to improve official monitoring plans and therefore further raise awareness of this issue between agriculture stakeholders, healthcare entities and non-professionals.

Struggling Thermal Stress Impacts on Growth Performance and Health Status of Newly Weaned Rabbits Using Nanoemulsion of Origanum majorana Considering the Economic Efficiency of Supplementation

With the recent trend of global warming, HS-instigated diminishing could extremely jeopardize animal health, productivity, and farm profit. Marjoram essential oil (MEOE) is a worthy source of wide range phytogenic compounds that may improve heat tolerance, redox and inflammatory homeostasis, and immunity of newly weaned rabbits, specifically if included in the diets in a nano form. One hundred newly weaned rabbits were randomly distributed into four homogeneous groups. The first group (control group) included rabbits that received basal diet without supplementation. In contrast, the other three groups included rabbits that received basal diets supplemented with 200 (MEONE200), 400 (MEONE400), and 800 (MEONE800) mg MEONE/kg diet, respectively. Among MEONE-treated groups and control groups, MEONE400 group showed the highest (p < 0.001) growth performance traits, including final body weight, average daily gain, feed efficiency, and the performance index. Compared to the control, all MEONE-supplemented groups possessed lower rectal temperatures and respiration rates, recording the lowest values in the MEONE400 group. The oxidative stress biomarkers and immunoglobulins G and M were significantly improved in the MEONE400 and MEONE800 compared with the control and MEONE200 groups. The addition of MEONE (400 or 800 mg/kg) decreased the concentrations of serum interleukin-4 (p = 0.0003), interferon gamma (p = 0.0004), and tumor necrosis factor-α (p < 0.0001) but significantly elevated (p < 0.001) the activity of nitric oxide, amyloid A and lysozyme. Liver functions (lower concentrations of liver enzymes) were significantly improved in all MEONE-treated groups compared to the control group. There was a considerable significant effect of dietary supplementation of MEONE400 on economic efficiency. In conclusion, the addition of 400 mg/kg to the diets of newly weaned rabbits can be recommended as an affective intervention to mitigate the negative impacts of HS.

Measuring the economic performance of small-scale rabbit production agribusiness enterprises

Reducing malnutrition and poverty remains at the centre of policy. Rabbit rearing, of great economic importance, is a critical pathway to achieving this. Good knowledge of the profitability of rabbit production and its driving factors can enhance participation in rabbit production. Thus, this study examined the economic performance (profitability) of rabbit production, the factors influencing profitability and its barriers. Descriptive statistics, profitability analysis, the Tobit regression model and Garret ranking were employed to achieve the objectives. The results indicated that rabbit production was economical, productive and profitable, with a gross margin of N675,990 (USD 1,633.5), a net income of N663,974 (USD 1,604.4), a profit ratio of 0.6, a benefit-cost ratio of 2.7, a return on capital invested of 1.7 and an operating ratio of 0.4. The factors that enhanced rabbit production profitability were stock size, education, experience, membership of the association and labour availability, whereas mortality, disease outbreaks and feeding costs were inhibiting factors to profitability. The major constraints affecting rabbit production are disease, a high mortality rate and poor access to credit. These call for the provision of disease management training and credits to motivate people to engage in rabbit farming, which will, in turn, lower poverty and increase protein availability.

Growth Performance, Digestive Efficiency, and Meat Quality of Two Commercial Crossbred Rabbits Fed Diets Differing in Energy and Protein Levels

The present study evaluated the effect of digestible energy (DE) and crude protein (CP) levels on growth, digestive efficiency, slaughter yield and meat quality in growing rabbits of two genotypes (Grimaud, G vs. Hyla, H). A total of 384 crossbred rabbits (192 G and 192 H), half males and half females, were divided into eight experimental groups according to a bi-factorial arrangement (2 genotypes × 4 diets; 48 animals/group) and reared in individual cages. From 33 to 64 days of age, rabbits were fed four diets obtained by combining two DE levels (high, HE—10.9 MJ/kg vs. low, LE—9.2 MJ/kg, on average) and two CP levels (high, HP—159 g/kg vs. low, LP—144 g/kg, on average). Then, all rabbits received the same fattening diet (10.7 MJ DE/kg; 156 g CP/kg) until slaughtering (77 days of age). Growth performance did not differ between genotypes for the entire trial (on average final live weight 3010 g; daily weight gain 50.5 g/d), but H rabbits showed a faster growth during the post-weaning period (p ≤ 0.01) compared to G rabbits, while exhibiting lower slaughter yield and lower carcass fatness (p ≤ 0.01). As DE level increased, feed intake decreased and feed conversion improved (p < 0.001), while caecal volatile fatty acid concentration increased and caecal pH and N-ammonia decreased (p ≤ 0.01). The reduction in the CP level did not affect performance and carcass traits. No significant interaction was detected between genotype and diet. In conclusion, G rabbits may have an advantage over H rabbits because of the higher slaughter yield. As for the nutritional characteristics of diets for high-producing crossbred rabbits, high energy levels are confirmed to enhance feed efficiency, whereas dietary CP can be reduced to 144 g/kg without negative effects on performance and carcass traits.

Marine Macroalgae in Rabbit Nutrition—A Valuable Feed in Sustainable Farming

Simple Summary

Commercial rabbit farming has faced critical challenges in the last few years, during which the ban on the prophylactic use of antibiotics in animal feed has added to the weakness of the production system and a decrease in consumption of rabbit meat. Considering the potential role of macroalgae as an alternative to the use of antibiotics in animal nutrition, this review paper aims to evaluate the use of macroalgae in rabbit farming. It specifically focuses on how macroalgae can be used sustainably to improve rabbit health as an economically viable alternative that could help guarantee the future of this high-value sector.

Abstract

The rabbit meat industry has faced critical challenges in the last few years, during which the ban on the prophylactic use of antibiotics in animal feed has added to the weakness of the production system and a decrease in consumption of rabbit meat. This review paper highlights the potential value of macroalgae in the rabbit farming sector as an alternative to the use of antibiotics to improve rabbit health. In line with sustainable agriculture programmes, the use of seaweed in rabbit nutrition may improve gut health according to the One Health approach, whereby consumers and the environment could receive tangible benefits. The inclusion of algae in animal feed has experimentally proven to help to reduce intestinal dysbiosis. However, further studies evaluating the prebiotic effects of algal components on gut health and also identifying the compounds directly responsible for the antimicrobial, antiviral, antioxidative and anti-inflammatory properties of algae are still needed. Furthermore, the inclusion of marine algae in rabbit food could potentially become a commercial marketing strategy that could attract new consumers who are concerned about environmental sustainability and who are looking for different, high-quality foods.

A pilot study about on-farm assessment of health and welfare in rabbits kept in different housing systems

This pilot study tested an on-farm protocol based on resource, management, and animal-based measures to evaluate the on-farm health and welfare of rabbits kept in four different housing systems. In detail, the four housing systems were (1) standard breeding cages for reproducing does (3,300 cm²) with their litters associated with bicellular cages for growing rabbits (1,200 cm²); (2) dual-purpose cages for both reproducing does and growing rabbits (3,655 cm²); (3) enriched cages (4,739 cm²) for both reproducing does and growing rabbits equipped with a wire-mesh elevated platform (1,015 cm²); (4) parks (30,977 cm²) made up of four modules (7,744 cm² each) joined by removing the wire net walls between them with growing rabbits kept in collective parks and reproducing does individually in the single modules. A total of 12 commercial farms (three farms/four housing systems) were visited during three seasons (summer, autumn, and winter) on two occasions each: (1) a pre-weaning visit for recordings on reproducing does and litters and (2) a pre-slaughtering visit for recordings on growing rabbits. At the pre-weaning visit, the prevalence of health concerns did not differ among does and litters kept in the different housing systems. At the pre-slaughtering visit, a higher prevalence of dermatomycosis was found in farms with dual-purpose cages and parks. Overall, taking into account the limitations due to the small sample size per housing system and the field conditions, the on-farm assessment tested in the present pilot study did not highlight major differences in the welfare and health of reproducing does and their kits as well as of growing rabbits in farms using different housing systems, which need to be confirmed on a large number of farms. The study also outlined the role of several management and environmental factors changing from one farm to another, which stresses the troubles of accounting for on-farm rabbit welfare and health exclusively to the housing system.

Use of Gnawing Hay Blocks: Effects on Productive Performance, Behavior and Reactivity of Growing Rabbits Kept in Parks with Different Sex-Group Compositions

To improve animal welfare in collective park housing systems, this study assessed the effects of the provision of gnawing hay blocks and the group composition (F: females, M: males, FM: mixed sex) on performance, behavior, and reactivity of 288 growing rabbits reared in 18 parks (16 rabbits/park) from 31 to 73 days of age. The presence of gnawing blocks inside the feeding area of the parks scarcely affected performance and budget time, but decreased the time spent in the resting area compared to parks without blocks (p < 0.001); it increased the time spent moving during the open field test (p < 0.05) and the rate of rabbits that approached the object in the novel-object test (p < 0.05). As for sex-group composition, the feed conversion ratio was lower in parks F and FM than in park M (p < 0.05). During the open-field test, FM rabbits spent more time moving (p < 0.05), whereas M rabbits displayed self-grooming for a longer time (p < 0.01). Results related to production, behavior, and reactivity indicate the provision of gnawing blocks for welfare improvement, but do not support the change from current mixed-sex to single-sex rearing.

Purchasing Habits, Sustainability Perceptions, and Welfare Concerns of Italian Consumers Regarding Rabbit Meat

Several factors drive consumer behavior in buying meat, particularly rabbit meat. The consumption of rabbits has decreased in Europe, and the main causes of this trend are an increasing association with the perception of rabbits as pets, consumers' changes in lifestyle, and eating habits. Additionally, increasing attention is paid to ethical issues regarding animal welfare. Investigating consumers' knowledge, perceptions, and concerns about rabbit meat production and consumption are crucial for improving market strategies. This study investigated consumers' perspectives of rabbit meat to provide useful information to producers for promoting this sector to consumers. A mixed-methods research design was applied. Qualitative data were collected through four focus group discussions involving 32 consumers and quantitative data through a semi-structured questionnaire administered nationally and completed by 1001 consumers. The limited use of antibiotics in inbreeding and the absence of animal suffering are factors that most influence consumers' willingness to purchase rabbit meat. Rural/domestic farms were recognized as places where animal welfare measures can be applied and have a positive influence not only on organoleptic quality but also on ethical value and food safety. The cage was perceived as unsuitable for rabbit growth and was oriented to a process of fattening based on industrial feed and antibiotics. Respondents sought information on rabbit farming during purchase, and the label was the most used tool. The rabbit meat production sector should consider these results to meet consumers' demands and raise awareness among operators on the use of animal welfare-based farming systems, helping to build a more positive image of the rabbit meat industry.

Rabbit meat trade of major countries: regional pattern and driving forces

In in the last 60 or so years, the global rabbit industry has been growing steadily. This paper studies the global rabbit meat trade by focusing on trade growth and regional pattern. First, rabbit meat productionand regional structure are introduced, as the basis of trade. Then, the global rabbit meat trade is studied in detail, including trade growth, regional structural changes, comparative advantages and competitiveness of major countries. Finally, a gravity model is built to test major factors affecting the rabbit meat trade andexplore the driving forces behind the trade. The data come from different channels, including the Food and Agriculture Organization of the United Nations, World Bank, the World Trade Organization and related government statistics. The results show that: (1) Over the past 60 yr, the global rabbit industry has achieved great progress. In the first half of the period, rabbit meat was mainly produced in Europe; then, rabbit meat production in Asia increased steadily and rapidly in the second half period, while European production decreased continuously. (2) The rabbit meat trade had been increasing for about 20 yr from 1961 to 1979, after which it fluctuated for another 20 yr. However, since 2001 it has been stable around an average level of 37 thousand tonnes, with only minor fluctuation. The trade pattern is currently from Asia (mainly China) and South America (mainly Argentina) to European countries. In 2018, the top 5 export destinations were Germany, Belgium, Italy, Portugal and France (3). Hungary and Argentina have been two strong competitorsin the last two decades, while Spain and Belgium are two new and promising countries in the rabbit meat trade. Now China no longer has comparative advantages in the rabbit meat trade (4). The gravity model results show that rabbit meat trade is mainly driven by demand. Countries with a high Gross Domestic Product tend to increase their imports more, but decrease their exports. Countries with higher populations export more rabbit meat but import less. Common language and contiguity of two countries have significant impacts on rabbit meat trade. Based on the above results, some suggestions and policy implications are provided. Rabbit farmers or processing companies should pay more attention to domestic consumers or neighbouring countries to survey potential markets; traders should explore more markets in order to reduce the degree of trade concentration and lower risks. Governments should popularise the nutritional knowledge of rabbit meat to encourage people (especially young people) to consume more healthy rabbit meat instead of pork, with a view to reducing obesity or other heart diseases, etc.

Evaluating Pain and Analgesia Effectiveness Following Routine Castration in Rabbits Using Behavior and Facial Expressions

Prevention of pain in rabbits is a priority for both welfare and validity of scientific data. We aimed to determine if the rabbit grimace scale (RbtGS) could be used as a viable, rapid assessment tool in two breeds of rabbit, Dutch belted (DB) and New Zealand white (NZW), following orchidectomy, as an adjunct to behavioral analysis. All animals received analgesia. Rabbits were filmed and their behavior was recorded at multiple time points pre- and post-orchidectomy. Observers then scored specific pain associated behaviors for analysis. Time matched footage was also scored using the rabbit grimace scale (RbtGS). Following surgery, rabbits showed significant increases in the duration spent displaying key pain associated behaviors at 1 and 5 h post-surgery. DB rabbits that received low dose meloxicam (0.2 mg/kg) showed significantly more pain behaviors at 1 and 5 h post-surgery compared to those administered a combination of higher dose meloxicam (0.6 mg/kg) and a lidocaine/bupivacaine local infusion. DB rabbits showed an increase in RbtGS score at both 1 and 5 h post-surgery. In the NZW rabbits, an increase in RbtGS score was only observed at 1 h post-surgery. Using behavioral analysis as the gold standard for comparison, the RbtGS was an effective means of determining when rabbits are painful following orchidectomy. Higher dose meloxicam (0.6 mg/kg) combined with local anesthetic was a more effective method of reducing pain, compared to lower dose meloxicam (0.2 mg/kg) alone.

Rabbit meat: valuable nutrition or too-cute-to-eat?

Rabbit meat is a component of traditional diets, often incorporated into iconic dishes of regional cuisine. Its consumption can be traced back to the ancient civilisations of the Mediterranean and beyond, well into the Palaeolithic era. Even though it has been representing considerable nutritional and cultural value for millennia, a decline in consumption is now noticeable. Specific categorial dynamics are at play, related to the various superimposed roles of rabbits as livestock, game, pests, laboratory animals and pets. Their perceived cuteness in particular can lead to emotional responses that are hard to reconcile with the sensitivities of the post-domestic paradigm. Such effects compromise the acceptability of rabbit meat in contemporary Western societies that are typified by problematic human-animal interactions and a disconnect from the food chain. Young and urban populations in particular now seem to have difficulties facing the notion that food production requires the killing of animals. As a result, a traditional food source risks becoming irrelevant despite its high nutritional value and potential for sustainable meat production, due to reasons that are emotive rather than rational.

Rabbit meat: valuable nutrition or too-cute-to-eat?

Rabbit meat is a component of traditional diets, often incorporated into iconic dishes of regional cuisine. Its consumption can be traced back to the ancient civilisations of the Mediterranean and beyond, well into the Palaeolithic era. Even though it has been representing considerable nutritional and cultural value for millennia, a decline in consumption is now noticeable. Specific categorial dynamics are at play, related to the various superimposed roles of rabbits as livestock, game, pests, laboratory animals and pets. Their perceived cuteness in particular can lead to emotional responses that are hard to reconcile with the sensitivities of the post-domestic paradigm. Such effects compromise the acceptability of rabbit meat in contemporary Western societies that are typified by problematic human-animal interactions and a disconnect from the food chain. Young and urban populations in particular now seem to have difficulties facing the notion that food production requires the killing of animals. As a result, a traditional food source risks becoming irrelevant despite its high nutritional value and potential for sustainable meat production, due to reasons that are emotive rather than rational.

Probiotics in Rabbit Farming: Growth Performance, Health Status, and Meat Quality

The rabbit's complex microbiota of the gastrointestinal tract (GIT) plays a critical role in feed digestion, in vitamin production, in fermentative activity with production of volatile fatty acids, and stimulation of immune response, as well as in the infection defence against pathogens and countering environmental stresses. To prevent digestive disorders of this fragile ecosystem, rabbit breeders adopt suitable diets supplemented with additives such as probiotics. Probiotics can interact with the host and with the other microflora leading to an increased health status. A review on the effects of probiotics on rabbit growth performance, health status, and meat quality was conducted to reduce the incidence of digestive diseases and enhance productive performance. Some authors observed that the supplementation of probiotics to the diet improved feed conversion ratio and growth and digestion coefficients, while other authors reported a lack of effect on the live performance. Benefits derived from the use of probiotics were observed on the mortality and the morbidity. The studies performed, to evaluate the effects of probiotic supplementation in diets on the immune response, showed variations in the results. Some authors reported no significant effect on haematological parameters, such as total protein, immunoglobulins, and IgG, while others observed a significant increase or decrease of the same parameters. Most of the research reported significant modifications of intestinal morphology and positive effects on the GIT microbiota, supporting the host's natural defences. Regarding the carcass and meat quality, the studies reported only partial and opposing results.

The Fatty Acid Profile of Meat from New Zealand White Rabbits Raised under Intensive and Extensive Production Systems

The aim of this study was to compare the fatty acid (FA) profile of meat from New Zealand White rabbits raised from 30 to 90 days of age under intensive (IPS) and extensive (EPS) production systems. In group IPS, the rabbits were housed in wire mesh cages with a slatted floor (16.7 animals/m²) and were fed a commercial pelleted diet. In group EPS, the rabbits were housed in free-standing cages on straw litter (2.5 animals/m²) and were fed a conventional farm-made diet (green fodder, barley grain, stale bread, hay). The FA profile of intramuscular fat (IMF) was analyzed in samples of Longissimus thoracis et lumborum (LTL) muscle. The analyzed production systems had no significant effect on the content of most FAs in IMF. However, the differences between group means contributed to more desirable values of the quality indicators of IMF (in particular in the LTL muscle) in group IPS. The study demonstrated that the claim that meat produced under less intensive farming systems is of superior quality could be an oversimplified generalization that should be validated in research.

The Economics of Rabbit Farming: A Pilot Study on the Impact of Different Housing Systems

This research evaluates the economic sustainability of rabbit farms using different housing systems-bicellular (BI), conventional dual-purpose (DP) and enriched cages designed according to the World Rabbit Science Association guidelines (WRSA)-through a field-based study involving six farms over the course of five years. The cages were compared based on three productivity indices expressed in kg of produced live weight/m² and on eight cost indices expressed in EUR/kg of produced live weight. The results showed that WRSA significantly reduced the productivity index per walkable cage area in buildings and cages, thanks to the longer platform area included in the cage compared to the other systems. Concerning cost indexes, total variable costs were not different among housing systems, whereas significant differences were observed within costs items. As for the feed costs, DP underperforms compared to BI or WRSA (1.15 vs. 1.02 and 0.99 EUR/kg produced live weight); for drugs costs, BI was less competitive compared to DP and WRSA (0.12 vs. 0.06 and 0.05 EUR /kg). In conclusion, under the conditions of the present study, the economic results of farms that adopted housing systems designed to improve rabbit welfare, such as WRSA enriched systems, were economically sustainable and, comparable to conventional housing systems based on BI or DP cages, also provided a significant reduction in drug use in the tested farms. A comprehensive collection of data from more farms at a European level would be necessary to confirm these results on the economics of farms adopting alternative housing systems for rabbits.

Dietary Supplementation of Olive Mill Waste Water Polyphenols in Rabbits: Evaluation of the Potential Effects on Hepatic Apoptosis, Inflammation and Metabolism through RT-qPCR Approach

Agro-industrial processing for the production of food or non-food products generates a wide range of by-products and residues rich in bioactive compounds including polyphenols. The concentration of these by-products is sometimes higher than in the original raw material as in the case of olive mill waste water (OMWW), one of the main by-products of olive oil extraction. Polyphenols are secondary plant metabolites that regulate the expression of specific inflammatory genes, transcriptional factors and pro/anti-apoptotic molecules, thus modulating the signaling pathways essential for cell health and homeostasis. The liver plays a key role in regulating homeostasis by responding to dietary changes in order to maintain nutritional and physiological states. In this study a nutrigenomic approach was adopted, which focuses on the effects of diet-health-gene interactions and the modulation of cellular processes, in order to evaluate the expression of the genes (AGER, BAX, COX2, IL1B, PPARA, PPARG, SIRT1, TNFA) involved in these interactions in the livers of rabbits fed with a diet supplemented with OMWW (POL) or without supplements (control, CTR). The RT-qPCR analysis showed the down-regulation of SIRT1, TNFA, AGER, BAX and PPARA transcripts in the POL group compared to the CTR group. These results show that OMWW dietary supplementation prevents cell death and tissue deterioration in rabbits.

Ameliorative Effect of Neem Leaf and Pomegranate Peel Extracts in Coccidial Infections in New Zealand and V-Line Rabbits: Performance, Intestinal Health, Oocyst Shedding, Carcass Traits, and Effect on Economic Measures

Healthy, weaned, coccidial-free male rabbits from two breeds (New Zealand white (NZ) and V-line (VL)) were divided into 10 equal groups (5 groups each for NZ and VL) (3 replicates/group, 6 rabbits/replicate, 18 rabbits/group). All rabbits were inoculated with 5 × 10⁴&nbsp;Eimeria spp. oocysts (E. intestinalis (67%), E. magna (22%), and E. media (11%)) except for the rabbits in the first group (G1), which were inoculated with a sterile solution and served as a negative control. The remaining four groups were treated as follows: G2, no treatment/positive control, G3, treated with neem leaf extract, G4, treated with pomegranate peel extract (PPE), and G5, treated with a combination of neem leaf extract and PPE. For both breeds, our results showed that the use of neem leaf and/or pomegranate peel extract resulted in improved growth performance, with a significant improvement in relative feed conversion ratio (FCR) compared to the positive control groups, which recorded the worst values, as well as a significant (p ≤ 0.05) reduction in mean oocyst count compared to the positive control groups. We also observed downregulation of mRNA levels of IL-1βα, IL6, and TNF-α in the herbal treatment groups compared with the mRNA levels of these genes in the positive control groups. Herbal treatment with neem leaf and/or pomegranate peel extracts had positive effects on the NZ and VL rabbits experimentally infected with mixed Eimeria species, as evidenced by their healthy appearance, good appetite, no mortalities, an anticoccidial index > 120, and a significantly higher total return and net profit when compared to the positive control groups of both breeds. In NZ rabbits, the treatment with neem leaf extract alone (G3) or in combination with PPE (G5) recorded the most efficient economic anticoccidial activity.

Modulation of Cathepsin S (CTSS) Regulates the Secretion of Progesterone and Estradiol, Proliferation, and Apoptosis of Ovarian Granulosa Cells in Rabbits

Simple Summary

In goat and sheep, CTSS is reported to be important for the development and maturation of oocytes by regulating cell proliferation and apoptosis. The purpose of this study was to investigate the role of CTSS in regulating cell apoptosis and hormone secretion in rabbit granulosa cells. Our results suggested that the CTSS gene can promote the proliferation of granulosa cells and reduce its apoptosis in vitro, while overexpression of CTSS promoted the secretion of progesterone and estrogen in rabbit granulosa cells. Therefore, manipulation of CTSS may improve development of oocytes, and thus provide an approach for better manipulation of rabbit reproductive performance.

Abstract

Cathepsin S (CTSS) is a member of cysteine protease family. Although many studies have demonstrated the vital role of CTSS in many physiological and pathological processes including tumor growth, angiogenesis and metastasis, the function of CTSS in the development of rabbit granulosa cells (GCS) remains unknown. To address this question, we isolated rabbit GCS and explored the regulatory function of the CTSS gene in cell proliferation and apoptosis. CTSS overexpression significantly promoted the secretion of progesterone (P4) and estrogen (E2) by increasing the expression of STAR and CYP19A1 (p < 0.05). We also found that overexpression of CTSS increased GCS proliferation by up-regulating the expression of proliferation related gene (PCNA) and anti-apoptotic gene (BCL2). Cell apoptosis was markedly decreased by CTSS activation (p < 0.05). In contrast, CTSS knockdown significantly decreased the secretion of P4 and E2 and the proliferation of rabbit GCS, while increasing the apoptosis of rabbit GCS. Taken together, our results highlight the important role of CTSS in regulating hormone secretion, cell proliferation, and apoptosis in rabbit GCS. These results might provide a basis for better understanding the molecular mechanism of rabbit reproduction.

Effects of Dietary Polyphenols from Olive Mill Waste Waters on Inflammatory and Apoptotic Effectors in Rabbit Ovary

The aim of this study was to evaluate the effect of dietary polyphenols on the expression of the effectors involved in inflammation and apoptosis in rabbit ovary. New Zealand White female rabbits were fed a basal control diet (CTR), or the same diet supplemented with a polyphenolic concentrate (POL, 282.4 mg/kg) obtained from olive mill waste waters. The follicle counts and the relative mRNA (RT-qPCR) and protein (immunohistochemistry) expression of the effectors involved in inflammation (cyclooxygenase-2; interleukin-1beta; tumor necrosis factor-alpha, TNFA) and apoptosis (BCL2-associated X protein, BAX), detected in the ovaries of both groups, were examined. The POL diet increased the primary and total follicles number. Cyclooxygenase-2 gene expression was higher (p < 0.05) in the POL group than in the CTR group, whereas BAX was lower (p < 0.05) in POL than CTR. Immunohistochemistry revealed the presence of all the proteins examined, with weaker (p < 0.05) COX2 and BAX signals in POL. No differences between the CTR and POL groups were observed for IL1B and TNFA gene and protein expression. These preliminary findings show that dietary polyphenols modulate inflammatory and apoptotic activities in rabbit ovary, regulating cyclooxygenase-2 and BAX expression, thus suggesting a functional involvement of these dietary compounds in mammalian reproduction.

A Comparison of the Quality of Meat from Female and Male Californian and Flemish Giant Gray Rabbits

This study aimed to compare the quality of meat (Longissimus thoracis et lumborum-LTL, hind legs-HL) from female and male Californian (CAL) and Flemish Giant Gray (FG) rabbits. The animals were kept outdoor, in a roofed pavilion, in wire mesh cages with a slatted floor and were fed ad libitum a complete pelleted diet. All rabbits were slaughtered at 91 days of age. The meat of CAL rabbits had a higher content of dry matter (p < 0.001), protein (p < 0.001) and unsaturated fatty acids (p = 0.002), higher pH (p < 0.001), and higher taste desirability (p = 0.021) and tenderness (p = 0.046). CAL rabbit meat had also a lower (p < 0.001) water to protein (W/P) ratio, lower (p < 0.001) shear force values, and lower (p = 0.042) taste intensity. The meat of FG rabbits was characterized by lower (p < 0.001) water-holding capacity (WHC). The LTL muscle had a higher content of dry matter (p = 0.003) and protein (p < 0.001), higher L* (lightness) (p = 0.011), b* (yellowness) (p < 0.001), and C* (chroma) (p = 0.010) values, and lower (p = 0.015) WHC. Hind leg muscles had higher (p < 0.001) fat content, a higher (p < 0.001) W/P ratio, and pH (p < 0.001). Sex had no effect (p > 0.05) on the analyzed meat quality attributes, excluding vitamin A content which was higher (p = 0.041) in females. In conclusion, the meat of CAL rabbits slaughtered at 91 days of age can be more mature than the meat of FG rabbits slaughtered at the same age. Furthermore, quality of meat from rabbits of both breeds depends on the anatomical origin of muscles. Further research is needed to identify the possible reasons for the higher vitamin A content of meat from female rabbits which did not differ from the meat of males in terms of other characteristics.

Recombinant myxoma virus infection associated with high mortality in rabbit farming (Oryctolagus cuniculus)

Myxomatosis is an emergent disease in the Iberian hare, having been considered a rabbit disease for decades. Genome sequencing of the strains obtained from Iberian hares with myxomatosis showed these to be distinct from the classical ones that circulated in rabbits since the virus introduction in Europe, in 1952. The main genomic difference in this natural recombinant hare myxoma virus (ha-MYXV) is the presence of an additional 2.8 kb region disrupting the M009L gene and adding a set of genes homologous to the myxoma virus (MYXV) genes M060R, M061R, M064R, M065R and M066R originated in Poxviruses. After the emergence of this recombinant virus (ha-MYXV) in hares, in the summer of 2019, the ha-MYXV was not detected in rabbit surveys, suggesting an apparent species segregation with the MYXV classic strains persistently circulating in rabbits. Recently, a group of six unvaccinated European rabbits (Oryctolagus cuniculus cuniculus) from a backyard rabbitry in South Portugal developed signs of myxomatosis (anorexia, dyspnoea, oedema of eyelids, head, ears, external genitals and anus, and skin myxomas in the base of the ears). Five of them died within 24-48 hr of symptom onset. Molecular analysis revealed that only the recombinant MYXV was present. This is the first documented report of a recombinant hare myxoma virus in farm rabbits associated with high mortality, which increases the concern for the future of both the Iberian hare and wild rabbits and questions the safety of the rabbit industry. This highlights the urgent need to evaluate the efficacy of available vaccines against this new MYXV.

Consumers' Attitude to Consumption of Rabbit Meat in Eight Countries Depending on the Production Method and Its Purchase Form

Simple Summary

The aim of the study was to investigate the consumers’ attitude to their preference of rabbit meat in eight countries depending on the production method and its purchase form. Consumers’ attitude was evaluated in Spain, Italy, France, Poland, Hungary, China, Brazil and Mexico based on the respondents’ opinion regarding origin, production conditions, slaughtering methods and breed. Results revealed that breed was an inessential factor. The origin of rabbits was the most important in Italy, France, Hungary and Brazil (in the latter country the slaughtering method and the level of processing were also highly valued), feeding of animals received the highest scores in Spain, Poland and Mexico (in the latter also the slaughtering method), while the level of processing was the foremost factor in China. The preference of fresh meat was the highest in Spain, France and Mexico, and that of frozen in Brazil and Mexico. The highest preference of a whole carcass was found in France and Mexico. The thigh was mostly favored in France and that of the loin in Mexico. The prepared meat products (roasted, smoked and semi-finished) were the most popular in Mexico. It can be concluded the preference of respondents depended on the country.

Abstract

The study’s aim was to investigate the consumers’ attitude to their preference of rabbit meat in eight countries depending on the production method and its purchase form. In Spain and China almost all factors got low scores. High scores (above 4 out of 5) for origin were found in Italy, France, Poland, Hungary and Brazil. The importance of feeding was highlighted in Italy, Poland, Hungary and Mexico. High values were received for housing conditions in Italy, Poland, Hungary and Mexico. The level of processing was the most important in China and Brazil, while the slaughtering method was considered the most important in Brazil and Mexico. Breed received the lowest score in almost all countries. The preference of fresh meat was the highest (above 50%) in Spain, France and Mexico, and that of frozen in Brazil and Mexico (about 20%). The highest preference for a whole carcass (above 50%) was given by the respondents in France and Mexico. Thigh was mostly preferred in France whereas consumers preferred loin in Mexico. Roasted, smoked and semi-finished forms were mostly favored in Mexico. It can be concluded that the preference of respondents depended on the country. Preferences were different among the Mediterranean countries, and also Latin American countries.