Showing papers in "World Rabbit Science in 2010"
TL;DR: The harmonization of rabbit carcass criteria is a result of an international work as mentioned in this paper, which specifies the main traits to be consider from the birth of the animal to carcass analysis, to define these traits with enough accuracy and to propose a common terminology.
Abstract: The harmonization of rabbit carcass criteria is a result of an international work. lts task was to specify the main traits to be considerad from the birth of the animal to carcass analysis, to define these traits with enough accuracy and to propose a common terminology. Work on harmonization has been initialized by the Mediterranean Rabbit Group Conference (BLASCO, OUHAYOUN and MASOERO, 1992), completad by several research teams and, finally, discussed during a round table of the Vth World Rabbit Congress (Corvallis, 1992). The proposal described in this work concerns: 1- growth, consumption and breeding measurments, preslaughter handling and slaughter processing, 2- dressing percentage analysis, 3- measurments or prediction of commercial and reference carcass composition. The work represents an official document of the World Rabbit Science Association. A commission has been created to examine the efficiency of the proposed criteria and to modify them according to what the scientific development and the practica! experience or thei use would recommend.
442 citations
TL;DR: The proposal described in this work updates the former proposal published in 1993, and has the status of official document of the WRSA.
Abstract: L'harmonisation des criteres d'etude de la carcasse du lapin est le resultat d'un travail international. Son objectif est de definir, avec une precision suffisante, les caracteres qui decrivent au mieux l'animal, de la naissance a l'analyse de la carcasse, et de proposer une terminologie commune. Ce travail concerne: 1- les criteres de croissance, de consommation et d'elevage, les traitements peri mortem, 2- l'analyse du rendement a l'abattage, 3- les mesures ou les predictions de la composition des carcasses refrigeree et de reference. Le present texte remplace celui qui a ete publie en 1993. Il a le statut de document officiel de la WRSA.
368 citations
TL;DR: This paper describes a standardized method for in vivo determination of total digestibility in rabbits and this new rnethod can be regarded as a baseline for calibrating individual laboratory procedures.
Abstract: Ce texte a pour objet de decrire une methode standardisee de mesure de la digestibilite totale des aliments chez le lapin. Cette methode a ete elaboree en commun au sein du Groupe Europeen de Nutrition Cunicole (EGRAN) qui rassemble six laboratoires appartenant a cinq pays (Belgique, Espagne, France, ltalie et Portugal). Cette nouvelle methode a ete concue pour etre a la fois precise, rapide, et reproductible. Facilement applicable a l'ensemble des laboratoires, elle peut desormais servir de reference dans le secteur cunicole. Cette methode utilise des lapins de 7 a 8 semaines loges en cages individuelles et nourris a volonte. La duree de la periode pre-experimentale est de 7 jours et celle de la periode de recolte de 4 jours seulement. Les conditions standardisees d´echantillonnage et de sechage sont decrites pour l'aliment et les faeces.
285 citations
TL;DR: This review is focused on the most studied and developed substances, commonly known as alternatives to dietary antibiotics, particularly as far as rabbit feeds are concerned, which successively deal with probiotics, prebiotics, enzymes and organic acids.
Abstract: This review is focused on the most studied and developed substances which are commonly knownas alternatives to dietary antibiotics, particularly as far as rabbit feeds are concerned. After a reminder of thereason to be and success of antibiotic growth promoters, and why they lately came to be banned in theEuropean Union, we successively deal with probiotics, prebiotics, enzymes and organic acids. Data on rabbitsare, as expected, quite scarce when compared to species such as pigs and poultry. Nevertheless, theavailable performance results are discussed together with the possible mechanisms of action. Special mentionis made of the effects of these substances on digestibility and caecal activity.
179 citations
TL;DR: The aim of this paper was to draw up a set of recommendations for applied nutrition and feeding trials with rabbits, in relation to certain aspects such as determining the nutritive value of raw materials or diets in growing or reproducing animals, studying digestive physiology and obtaining growth and reproduction parameters.
Abstract: The aim of this paper was to draw up a set of recommendations for applied nutrition and feeding trials with rabbits, in relation to certain aspects such as determining the nutritive value of raw materials or diets in growing or reproducing animals, studying digestive physiology and obtaining growth and reproduction parameters. We deal first with animals, size of the sample, housing conditions, diets, handling, measurements, and the data analyses relevant to the design of the experiment are described. Secondly, we give a list of recommended items and include some comments.
116 citations
TL;DR: A critical review of the existing literature on rabbit welfare with special emphasis on housing conditions is provided, which should provide the basis for future European and national regulations.
Abstract: Research on rabbit welfare has been fragmentary and to date has been performed by only a few European teams who have often neglected the productive and commercial aims of rabbit rearing. With European Project COST Action 848 (Multi-facetted research in rabbits: a model to develop healthy and safe production in respect with animal welfare), rabbit welfare began to be considered in European research projects with the focus mainly on ethology, welfare evaluation methods, doe-litter relationships, man-animal relationships, and reproducing and fattening housing systems. As regards legislation, since 1996 the Standing Committee for the protection of animals kept for farming purposes established in the European Council by the Convention on the Protection of farm animals (ETS 87/1976) has been preparing specific recommendations to ensure improved welfare of domestic rabbits kept for commercial purposes, which should provide the basis for future European and national regulations. The European Commission asked the European Food and Safety Authority (EFSA) for its opinion on "The impact of the current housing and husbandry systems on the health and welfare of farmed domestic rabbits". The present paper provides a critical review of the existing literature on rabbit welfare with special emphasis on housing conditions.
108 citations
TL;DR: A literature review focusing on the milk yield and milk composition of rabbits and the non-nutritional factors affecting both quantity and quality is presented in this article, where the number of suckling kits, parity order (primiparous vs. multiparous) and the gestation overlapping degree (rapid decline after 17-20 days of gestation).
Abstract: This literature review focuses on the milk yield and milk composition of rabbits and the non-nutritional factors affecting both quantity and quality. Actual highly efficient hybrid does have an average daily milk yield of 250 g or 60 g/kg of live weight during the 4-weeks lactation period. However, compared with cow and sow milk, rabbit’s milk is much more concentrated in fat (12.9 g/100 g), protein (12.3 g/100 g) and energy (8.4 MJ/kg) which explains the extremely rapid growth of the young (weight × 6 after 3 weeks). Characteristic of rabbit milk is also the nearly absence of lactose (<2 g/100 g). At peak lactation, protein output per kg metabolic weight (13.4 g/day/kg 0.75 ( exceeds even those of Holstein milk cows. The non-nutritional factors having the largest impact on the milk yield are the number of suckling kits, the parity order (primiparous vs. multiparous) and the gestation overlapping degree (rapid decline after 17-20 days of gestation). However, also through the reduction of feed intake, heat stress has a detrimental impact especially when the night temperature remains above 25°C. Rabbit milk lipids are highly saturated (70.4% SFA) due to the high content of C 8:0 – C 12:0 (50% of total FA) and further characterised by nearly equal quantities of oleic and linoleic acid and an w-6/w-3 ratio around 4. Finally some data about the amino acid, milk proteins including the immmunoglobulins, mineral and vitamin composition are presented.
106 citations
TL;DR: This review analyses the variations in muscular pH and related traits in rabbits and concludes that even when chilling is intense, the phenomenon of "cold shortening" does not seem to be of major significance in rabbits.
Abstract: After reviewing muscular biology and general relationships between muscular physico-chemistry and meat quality, this review analyses the variations in muscular pH and related traits in rabbits. Among biological factors (muscle, age, genotype, family), muscle factor is the most important. lt determines the differences in ultimate pH (pHu) between muscles, which can reach 0.7 units and which are due to differences in the fibre typology. lncrease in glycolytic metabolism during muscle growth is accompanied by pHu lowering; its variation depends on the precocity of muscle development. Comparative studies of breeds do not show any evidence of differences in pH above 0.2 units; no breed presents abnormal acidification or pHu kinetics, which might entail anomalies in Water Holding Capacity or other qualitative traits in meat. Wlthln breed, the existence of correlations between pHu and growth characteristics may lead to a reduction in meat quality when strains are selected for weight productivity. The effect of dietary faetors is relatively small. When they can be detected, pH variations mostly correspond to modifications in growth rate. Thus the pHu of meat is lowered when growth is stimulated by a high level of nutrition or a high protein content. Slaughter faetors have a marked influence on muscular pH. Transport leads to a noticeable rise in pHu, a result of ante mortem depletion of glycogenic reserves; when subjected to prolonged stress, meat is darker and has a higher water holding capacity. Electroanaesthesia accelerates muscular acidification without modifying pHu. careass ehllling slows down the physico-chemical processes of rigor mortis: it slows down the fall in pH and reduces the intensity of sarcomere retraction. Even when chilling is intense, in spite of sorne contradictions in published literature, the phenomenon of "cold shortening" does not seem to be of major significance in rabbits. During meat storage in refrigerated form, after a certain latency period, the maturation processes are witnessed by de-amination of the proteins and thus by a raised pH. Freezing slows down this process, but does not avoid a rise in pH after several months in storage.
97 citations
TL;DR: In this paper, the digestibility data were selected after a compilation of original literatura data and a discussion between the authors, and the methodology used, in the different in vivo assays, was evaluated accurately in order to judge the reliability of the data.
Abstract: Feedstuff tables are presentad including the composition and the nutritive value of 53 raw materials used in compound diets for intensively reared rabbits. Each raw material is characterised by 23 analytical data and its digestible protein and energy values. Because of the importance of the fibre fractions in the nutrition of the rabbit, special efforts have been done to characterise the carbohydrate complex. The digestibility data were selected after a compilation of original literatura data and a discussion between the authors. The methodology used, in the different in vivo assays, was evaluated accurately in order to judge the reliability of the data. Besides digestible and metabolisable energy values are also presentad because they lead to a better mutual comparison between raw materials for formulation purposes. Finally, attention has been drawn that the presentad nutritiva values fit well with the proposed nutrient composition and show coherence in each category of feedstuffs.
84 citations
TL;DR: The present study summarizes the state of nitrogen nutrition in rabbits and reviews the role of protein and amino acids in rabbit health and the new nitrogen value of protein sources based on true ileal digestibility (TID) for future recommendations.
Abstract: In the European context, the new legislation to avoid mineral contamination and the ban on antibiotics as growth promoters has led to the definition of new objectives in respect of nitrogen supply. The present study summarizes the state of nitrogen nutrition in rabbits and reviews the role of protein and amino acids in rabbit health and the new nitrogen value of protein sources based on true ileal digestibility (TID) for future recommendations. The main sources of nitrogen for microbial growth are ammonia, urea and protein (endogenous and dietary). The surplus of nitrogen flow to the caecum increases mortality rates during fattening by favouring the growth of potential pathogenic bacteria. Accordingly, feeding strategies to reduce ileal nitrogen flow have been reviewed. A large reduction of dietary protein level might have negative consequences on growth performances and mortality. In order to formulate balanced low protein diets, data on ileal and faecal amino acid digestibility of 14 raw materials is summarized. The use of this different unit for amino acid digestibility is also discussed.
72 citations
TL;DR: Fat addition to the diet, both as inclusion leve! and source, significantly affects carcass fatness and meat fatty acid composition, and the consequences are evident in the organoleptic appreciation of rabbit meat and also in its technological characteristics.
Abstract: The principal objectives of rabbit feeding strategies are to limit digestive disorders, shorten rearing time and increase dressing percentage. Besides, new attention is placed on the carcass composition in terms of primal joint cut, fat and lean proportions, and on the technological and sensory characteristics of the meat, due to the increasing demand for processed meat. The possibility of modifying carcass and meat quality has been demonstrated to be very limited when rabbits are fed a balanced diet ad libitum. Only extreme situations like severe restriction and lack or large excess in a specific nutrient are able to influence slaughter traits and meat characteristics. However, growth performance and health conditions may be also compromised. The manipulation of the development rate of the different body tissues seems to be possible through adequate feeding programs based on different protein levels in relation to dietary energy, but more studies are required to clarify the variations of protein and amino acid requirements throughout the entire growing period. From the literature, it clearly appears that fat addition to the diet, both as inclusion leve! and source, significantly affects carcass fatness and meat fatty acid composition. The consequences are evident in the organoleptic appreciation of rabbit meat and also in its technological characteristics. Therefore further studies are required in order to investigate the biochemical processes that determine post-mortem transformation of muscles into meat and the evolution during storage.
TL;DR: Both temperature and the change in corticosterone level show that the stress reaction induced by tonic immobility test is stronger than the one due to the other stressors applied to rabbits.
Abstract: Among the main physiological stress indicators, the temperature evaluation is very important and innovative because it may be monitored without directly interacting with the animal. The use of a thermographic system, which is based on the detection of infrared radiation emitted by a subject, is a suitable method in order to measure temperature without any contact. In this research, a thermographic system was employed in order to single out the rabbit skin's zones most suitable for the temperature monitoring during stress challenges. Six hybrid rabbits were observed during induced stress; the areas selected as reference were: the ocular area (globe and periocular area), the internal auricle pavilion, and a shaved area of the head. The results of this pilot study show that the thermographic technique is a suitable method for the evaluation of temperature on rabbit. The best areas singled out were the eye bulb, the periocular area and the ear skin. The results concerning the effect of stress on cutaneous temperature showed that during stress condition a decrease in temperature occurs with respect to the basal condition (AT~1°C) and this trend is more evident for the auricle pavillion. In fact, this reaction is more evidenced in the ear skin, where a vasoconstriction process occurs. Moreover, corticosterone levels slightly increase (P=0.08) following the stressor's challenge due to tonic immobility test. In this research, both temperature and the change in corticosterone level show that the stress reaction induced by tonic immobility test is stronger than the one due to the other stressors applied to rabbits.
TL;DR: Correlation analysis indicates that meat from the fore leg is a good predictor of the chemical composition of the whole carcass meat (r=0.82 for crude protein, r = 0.92 for crude fat and r =0.95 for moisture).
Abstract: Thirty commercial rabbit carcasses weighting 836-1413 g were sealed in the Spanish market and were retailed according to the WRSA norms to obtain four parts: fore legs, thoracic cage, loin and hind part. The loin was separated into abdominal walls, Longissimus dorsi (LD) muscles and spine cut; hind legs and sacrum were separated from the hind part. Each joint was carefully dissected to separate edible meat from bone. Meat of each of the 210 samples (180 from joints and 30 representing meat from the whole carcass) was ground and was scanned by NIRS reflectance in quadruplicate; the four spectra from each sample were averaged. 36 samples were selected according to spectra characteristics and chemically analysed for crude protein, crude fat and moisture content and then used for re-calculating some previously obtained equations of calibration. With the new equations, the chemical composition of the 174 samples not analysed was determined. Meat from the fore legs had 20.2% of protein, 7.4% of fat and 71.2% of moisture; thoracic cage meat had 18.7%, 12.8% and 66.9% respectively; LD muscle: 22.1%, 1.2% and 75.6%; abdominal walls 20.9%, 7.6% and 70.1%; spine meat: 20.7%, 7.9% and 70.0%; hind leg meat: 21.2%, 3.0% and 74.7%; meat from the whole carcass: 20.8%, 7.1% and 71.2%. Correlation analysis indicates that meat from the fore leg is a good predictor of the chemical composition of the whole carcass meat (r = 0.82 for crude protein, r = 0.92 for crude fat and r = 0.95 for moisture).
TL;DR: Dans une premiere experimentation, six lapins males Neo Zelandais Blancs ages of 12 a 15 mois, ont ete soumis aux conditions hivernales puis estivales pour etudier l'influence de the saison chaude sur quelques constituants sanguins et sur the qualite du sperme des lapins .
Abstract: Dans une premiere experimentation, six lapins males Neo Zelandais Blancs ages de 12 a 15 mois, ont ete soumis aux conditions hivernales (16 ± 3oC et 71 ± 8 % HR) puis estivales (35 ± 3oC et 46 ± 8 % HR) pour etudier l'influence de la saison chaude sur quelques constituants sanguins et sur la qualite du sperme des lapins . males. Les resultats montrent que durant la saison chaude, dans le sang, les taux de glucose, de cholesterol, de phospholipides, de Jipides totaux et l'activite de la transaminase augmentent significativement, tandis qu'une diminution significative des taux de proteines, d'albumine et de testosterone est enregistree. Pendant la saison chaude, on constate un augmentation a la fois du taux de transaminase du sperme et du pourcentage de spermatozoldes morts, du cholesterol et des lipides totaux dans le liquide seminal, tandis que Je taux de spermatozoldes total, et vivants, et Je pourcentage de motilite des spermatozoii:Jes diminuent significativement. De plus la saison chaude provoque une baisse des valeurs moyennes du taux de conception % (P<0.01) et de la taille de la portee a la naissance (P<0.05) compares aux valeurs hivernales. Dans une seconde experimentation, conduite durant la saison chaude, 3 x 6 males NZW ont recu un regime standard supplemente ou non avec O. 7 mg de Se + 40 mg de Vit. E/kg M.S., ou 35 mg Zn/kg M.S. Une augmentation significative du taux de testosterone sanguine, de la concentration du sperme et de l'activite de la transaminase a ete enregistree avec la supplementaire Se + Vit. E, tandis que la supplementaire en Zn du regime de base provoque une diminution a la fois dans le sang et dans le liquide seminal du taux de cholesterol, de lipides totaux et de transaminase. Au contraire, un augmentation significative des taux de testosterone a ete detectee. Toutefois, le volume de sperme, la concentration totale et ce/le des spermatozoldes vivants, le % de motilite, le taux de conception % et la taille de la portee ont ete augmentes par l'apport de Zn aux /apins males stresses par la chaleur.
TL;DR: This review analyses the main factors of success of insemination as well as the methods suitable for oestrus induction in order to improve reproductive efficiency of rabbit does in term of fecundity (combining fertility and prolificacy).
Abstract: This review analyses the main factors of success of insemination as well as the methods suitable for oestrus induction in order to improve reproductive efficiency of rabbit does in term of fecundity (combining fertility and prolificacy). Parity, lactation status, pseudopregnancy as well as sexual receptivity at the time of insemination highly influence reproductive performance. Pseudopregnancy (ovulation non-induced by GnRH or mating) strongly depresses fertility, but its cause is still unknown. The routine use of eCG (or PMSG) on lactating does consistently increases the proportion of receptive does at the time of AI and, therefore, their long-term productivity, without any important side-effect. Applied just before insemination, different alternative methods have been studied: animal manipulation (a change of cage, does gathering), ?buck? effect, short damlitter separation, feeding programmes and light stimulations. Some of these methods improve the fecundity, but they sometimes also decrease kits growth (dam-litter separation, lighting programmes...). Consequently, for an optimal application in farms, it is important to consider long-term effects, such as global productivity and persistency of the effects. However, a better knowledge of the underlying physiological mechanisms would allow a better control of reproduction in rabbit farms.
TL;DR: The analysed blood parameters showed the rabbits fed on the control diet to be superior in haematocrit, haemoglobin concentration, red and white cells numbers, and cholesterol values were statistically higher in rabbits on thecontrol and cassava roots diets than on the 2 others which have a higher fiber content.
Abstract: The grain replacement value in rabbit diets of three tropical alternativa feed resources, namely maize offal (MO), unpeeled cassava root meal (UCRM) and cassava peel meal (CPM) was investigated in a ten week feeding tria! with growing rabbits, in comparison with maize. The introduction ratas were 30.8% of the diets, and the initial age of the 24 rabbits was 5-6 week. The criteria for assessment were growth performance, nutrient digestibility and blood composition at the end of the experimental period. Average daily gain and daily feed intake of the rabbits variad from 13.0 g on CPM diet to 14.2 g on MO diet, and 60. 7 g on UCRM diet to 71.4 g on CPM diet respectively. However, both MO and CPM were significantly consumad (P < 0.05) more than the other diets. Feed conversion and protein efficiency ratios were significantly inferior (P < 0.05) on CPM diet than on others. The dry matter, cruda protein, gross energy, ether extract and cruda fibra digestibilities were numerically highest in the control diet, but statistically comparable for rabbits on UCRM diet; both were however significantly higher (P < 0.05) than records for rabbits fed on MO and CPM basad diets. The analysed blood parameters showed the rabbits fed on the control diet to be superior in haematocrit, haemoglobin concentration, red and white cells numbers. The mean corpuscular volumes and mean corpuscular haemoglobin were highest in the cassava root diet followed by cassava peel basad diet, while the mean corpuscular haemoglobin concentration values were statistically similar in all the diets. Serum total protein variad between 6. 75 g/100 mi in rabbits fed on maize offal to 5.81g/100 mi on cassava roots without any significant difference. A similar pattern was repeated for albumin and globulin fractions. Both creatinine and uric acid concentrations were respectively uniform amongst the rabbits on different treatments. However, a significantly lower (P < 0.05) level of urea-nitrogen was determinad in the serum of rabbits fed on cassava peel diet. Serum glucosa level ranged between 125 mg/100 mi in rabbits fed on the control diet to 192 mg/100 mi for their counterparts on cassava roots diet showing a significantly lower content (P < 0.05) on the control and cassava peel basad dietary treatments. Cholesterol values were statistically higher (P < 0.05) in rabbits on the control and cassava roots diets than on the 2 others which have a higher fiber content.
TL;DR: In conclusion, intra-litter homogenisation of birth weight markedly reduced mortality in small rabbits and standard deviation in live weight within litters.
Abstract: Two experiments were performed with Pannon White rabbits. In the first experiment 50 litters were formed with 6, 8 or 10 rabbits of different birth weight in equal ratios (n = 380, between 39 and 70g). In the second experiment 60 litters of 6, 8 or 10 rabbits were formed (n = 456), each litter consisting of rabbits of a single weight group only (small: 39 to 43g; medium: 53 to 56 g; large: 63 to 70 g). With increasing birth weight and decreasing litter size, mortality in the suckling rabbits decreased and daily weight gain of kits and weight of rabbits up to 10 weeks of age increased significantly. These effects were weaker in experiment 2. In the extreme groups used in the experiments (10 small kits and 6 large kits) the following results were obtained: mortality between birth and 21 days was 35.3 and 8.1 % in experiment 1 and 18.0 and 5.6 % in experiment 2, daily weight gain of kits between birth and 21 days was 9.2 and 18.5 g in experiment 1 and 10.8 and 16. 7 g in experiment 2, and body weight at 10 weeks of age was 1.90 and 2.58 kg in experiment 1 and 2.11 and 2.45 kg in experiment 2. In conclusion, intra-litter homogenisation of birth weight markedly reduced mortality in small rabbits and standard deviation in live weight within litters.
TL;DR: In this article, a group of hybrides sevres, individuellement controles, ont ete nourris ad libitum avec un aliment A (16,4 % d'amidon, 15,3 % de fibres brutes) ou B (248 % d"amidon and 11,6 % de fibers brutes), de 28 a 49 jours d'age.
Abstract: 1200 lapins hybrides sevres, individuellement controles, ont ete nourris ad libitum avec un aliment A (16,4 % d'amidon, 15,3 % de fibres brutes) ou B (248 % d'amidon et 11,6 % de fibres brutes) de 28 a 49 jours d'age. Le gain de poids vif n'a pas ete affecte par l'aliment (37, 7 g/jour). La consommation et /'indice de consommation etaient plus eleves avec l'aliment A (95,5 vs 84,5 g/jour et 2,55 vs 2,27 g/g, P<0.001 ). En outre la mortalite etait plus faible avec cet aliment A ( 4,7vs 8,0 %, P<0.05). Un autre groupe de 60 lapins fut abattu a 38 ou 49 jours d'a.ge, l'amidon du contenu de l'ileon distal et du caecum ont ete analyses. La teneur en amidon du contenu ileal et sa difference avec la teneur du contenu caecal varient en fonction de l'aliment (plus eleve pour l'aliment B, P<0.001) et de /'a.ge (plus eleve a 38 jours, P<0.001); l'interaction entre l'aliment et l'a.ge est significative (P<0.05), la difference entre les aliments etant plus importante pour les lapins les plus jeunes.
TL;DR: This paper summarised the recent advances and perspectives, which it is considered significant in the field of the nutrition of growing rabbits and reproductive females, which include dietary fibre definition and requirements and the relationship with digestive pathology, as mortality by diarrhoea is still a majar question in rabbit breeding.
Abstract: The rabbit meat production knew deep modifications during the ten last years, on the techniques of breeding as well as on the genetic potentialities of growth or reproduction. The techniques of feeding (adapted feed formulation etc.) also strongly progressed, in arder to obtain a better adjustment of feeds to the animals needs, e.g. according to their physiological stage. This paper summarised the recent advances and perspectives, which we consider significant in the field of the nutrition of growing rabbits and reproductive females. Particular attention will be devoted to the dietary fibre definition and requirements and to the relationship wilh digestive pathology, as mortality by diarrhoea is still a majar question in rabbit breeding.
TL;DR: The purpose of this experiment was to verify the compatibility of a group housing system, from weaning to slaughter, with the rabbit modern productive standards, evaluating the effects of different stocking densities and type of litter on health, performances and some aspects of carcass and meat quality.
Abstract: The purpose of this experiment was to verify the compatibility of a group housing system, from weaning to slaughter, with the rabbit modern productive standards, evaluating the effects of different stocking densities and type of litter on health, performances and some aspects of carcass and meat quality. Two experiments were carried out. In the first, 184 rabbits were housed in two-places, either wire mesh cages (16/m 2 ) or in 1.0 m 2 pens on a straw litter at 2 densities (8 or 16 rabbits per m\ in the second experiment, 232 rabbits were housed in the same pens and al the same densities on either straw or wood shavings, while the control group was traditionaliy housed in cages of 2 rabbits. In experiment 1, mortality rate was significantly higher fer rabbits raised on litter al the higher density (15.6% vs 4.2% and 7.5% fer groups housed on litter at low density or in cages, respeclively). Higher death incidence was mainly due to coccidiosis. Thus, a prophylactic treatment was provided to all the animals befere the beginning of experiment 2 resulting in a lack of differences in mortality rate among the groups (9.91 % average). Rabbits housed in cages showed a significantly higher weight gain (41.0 vs 31.7 and 34 g/d) and a better feed efficiency than rabbits housed on litter in experiment 1. On the contrary final live weight, daily weight gain and feed to gain ratio fer caged animals were not significantly higher than fer rabbils housed on litter in experiment 2. However, growth rate of rabbits kept al lower density was significantly higher than fer the other animals reared in pens (33.2 vs 31.0 g/d), while the type of litter had no effects. Caged animals showed a carcass weight and dressing out percentage significantly higher than ali the other groups in the first experiment. Furthermore, the hot carcass weight among rabbils housed on litter was significantly higher fer lower stocking density. In experiment 2, dressing out percentage was significantly better in caged rabbits (57.4%) than in all the other experimental groups (55.1 to 55.8%). Moreover, carcass weight was significantly higher in rabbits kept at lower density than the others ones reared in pens (P<0.05). The full gastrointestinal tract was significantly heavier in rabbits housed in pens on straw litter (22.3% of live weight) in comparison with the caged animals (18,7%). The chemical composition of the caecal content however did not show variation of the gross composition as a function of the litter type. In experiment 1, the meat pH al 45 min and al 24 hrs post mortem, as well as meat colour parameters were the same in all experimental groups. In experiment 2, it can be observed that the hind leg weight was constant among the groups, while the muscle to bone ratio of the cut was significantly higher in caged than in ali the other animals. Furthermore, rabbits on litter had on the whole meat with a higher water and a lower lipid content. In conclusion, group housing systems on litter implies some relevant questions that have to be pointed out, particularly concerning pathology problems (mainly connected to coccidiosis) compared to the intensive breeding in cages. Growth perfermances, slaughter results and carcass quality are on the whole better fer animals traditionaliy raised in wire mesh cages.
TL;DR: The effect of transport duration and gender on carcass and meat quality, reared in individual cages from 35 d of age until slaughter at 77 d, was evaluated and gender was appreciable at slaughter.
Abstract: In order to evaluate the effect of transport duration and gender on carcass and meat quality, 204 rabbits were reared in individual cages from 35 d of age until slaughter at 77 d (average live weight at shipping: 2662±189 g). Before slaughter, four groups of rabbits were formed and transported for 2, 4, 6, or 8 hours from the breeding unit to the slaughterhouse. Increasing the duration of transport increased transport losses (2.44% to 4.59%; P<0.001), decreased dressing percentage (59.5% to 58.9%; P<0.01) and increased the redness of the longissimus dorsi muscle (CIE a* 2.38 to 2.73; P<0.05). Commercial carcass grading for colour, conformation and fatness were not affected by transport duration. The effect of gender was appreciable at slaughter: final live weight and transport losses were higher in females than males. Dressing percentage was lower in females (59.1 vs 59.8%; P<0.01) due to the greater gut content. Carcasses of females showed a higher proportion of longissimus muscle (P<0.01). The meat of females was darker (CIE L* of biceps femoris muscle: 54.9 vs 55.9; P<0.01) and less coloured (Chroma index of longissimus lumborum muscle: 3.52 vs 3.87; P<0.05) than males.
TL;DR: The scientific community which uses rabbits as experimental animals or as a tool to produce biotech products, as well as those involved in breeding, are invited to focus their efforts on this species.
Abstract: The first transgenic rabbits were obtained two decades ago by pronuclear microinjection. Several characteristics of rabbit made it the first and classical model for the study of lipoproteins and atherosclerosis. Rabbit models include normal cholesterol-fed rabbits, spontaneous mutants for lipid metabolism and transgenic rabbits. Though most molecular investigations of the cardiovascular system have used transgenic mice, the small rodents do not accurately reflect crucial facets of human cardiovascular physiology, therefore a number of different transgenic rabbit models of hypertrophic cardiomyopathy were created. Transgenic rabbits have been found to be suitable bioreactors for the production of pharmaceutical proteins filling an important niche between the laboratory mouse and larger farm mammals. It is the smallest animal that can be used to produce recombinant proteins in its milk or serum both on an experimental and a commercial scale. The rabbit appears particularly flexible for the preparation of human antibodies, and recombinant human proteins for replacement therapies have also been produced in rabbit milk. A specific biotechnology of the rabbit is emerging. The scientific community which uses rabbits as experimental animals or as a tool to produce biotech products, as well as those involved in breeding, are invited to focus their efforts on this species.
TL;DR: The repeatability animal model and the genetic parameters used are unsuitable for selecting for litter size at weaning and models taking into account effects such as dominance need to be investigated.
Abstract: An evaluation of genetic response on reproductive traits was carried out in a line of rabbits selected for litter size at weaning. The evaluation was performed comparing contemporary does of generation 17 and 26, using cryopreservation techniques. The direct response to selection between both generations was 0.77±0.27 rabbits weaned/litter and there were favorable correlated responses in total litter size at birth and born alive. There was a non-significant response in prenatal traits, but the litter size results imply response probably in foetal survival. The genetic trends were also estimated using mixed model methodology and were higher than the previous ones. Therefore, the repeatability animal model and the genetic parameters used are unsuitable. Models taking into account effects such as dominance need to be investigated.
TL;DR: A very quick and significant rise in the a-linolenic acid content in meat from rabbits fed during the finishing period with a diet containing 8% linseed is indicated, indicating that care must be taken to avoid lipid oxidation and detrimental effects on the sensory qualities of meat and meat products during processing and subsequent storage.
Abstract: The effect of dietary use of dehydrated lucerne meal (DLM) and whole linseed (LIN) on chemicalphysical traits, fatty acid composition, susceptibility to lipid oxidation, and sensory quality of rabbit meat and meat products (hamburgers) was studied. Two groups of 128 weaned rabbits (37 d-old) were fed on diets containing 25 or 35% DLM. At 64 d of age, the rabbits were randomly divided into four groups; two of them received the same diet whereas the others were fed on diets containing both 25 or 35% DLM and 8% linseed until slaughtering (87 d). The main effects of DLM (25 vs. 35%) and LIN (0 vs. 8%) were considered according to a 2×2 factorial statistical design. With regard to the effect of lucerne, the main result was the higher content of a-linolenic acid in meat from rabbits fed the higher level of DLM (6.34 vs. 5.82% in DLM35 and DLM25, respectively; P<0.05) without impairing the lipid susceptibility to oxidation. The use of linseed strongly (P<0.01) influenced the fatty acid composition of the meat by enhancing the content of polyunsaturated fatty acids (PUFA, 33.68 vs. 27.79%; for LIN8 and LIN0, respectively) and mainly a-linolenic acid which was three times higher in LIN8 rabbits (9.42 vs. 2.95%; P<0.01), producing a lower n-6/n-3 PUFA ratio (2.28 vs. 6.59; P<0.01). However, the higher level of PUFA was related to a higher susceptibility to lipid oxidation (TBARS) of both meat and frozen (-20°C for 3 or 6 months) meat batters for hamburgers production. Despite the higher TBARS, sensory differences among hamburgers were detected only at six months frozen storage. Finally, the use of linseed did not determine a higher colour variation of the packaged hamburgers during storage (14 d at 2-4°C). This experiment indicates a very quick and significant rise in the a-linolenic acid content (three times higher after 3 weeks) when rabbits were fed during the finishing period with a diet containing 8% linseed. However, despite the nutritional importance of this essential fatty acid, care must be taken to avoid lipid oxidation and detrimental effects on the sensory qualities of meat and meat products during processing and subsequent storage.
TL;DR: The highest frequency of nursing in domestic rabbits was found in the first two hours after onset of dusk, whereas the peak in nursing activity in wild rabbit does was postponed after midnight, so light-dark change influences the time of Nursing in both wild and domestic rabbits.
Abstract: lnvestigations were carried out during 104, 24-hours intervals in wild rabbits and 257, 24-hours intervals in domestic rabbits kept in two enclosures measuring 150 m2 each. Both wild and domestic rabbit does nurse their pups more than once a day (wild rabbits: 1.28 per 24 h; domestic rabbits: 1.12 per 24 h) with the highest frequency in the 2nd week of lactation (wild rabbits: 1.48 per 24 h; domestic rabbits: 1.27 per 24 h). During the night, 84% and 86% (wild, domestic rabbits, respectively) of all nursing took place. Light-dark change influences the time of nursing in both wild and domestic rabbits. The highest frequency of nursing in domestic rabbits was found in the first two hours after onset of dusk, whereas the peak in nursing activity in wild rabbit does was postponed after midnight.
TL;DR: Regardless of the production purposes of the breed (meat or fur), carcass yield and meat quality are very similar for rabbils slaughtered at 2.00 kg.
Abstract: The objective of this work was to determine the differences on yield and quality of carcasses of different sex (male and female) and breed (New Zealand (NZ), Californian (CA), Chinchilla (CH) and Rex (RX)). Ten rabbits (balanced sexes) of each breed were used. Rabbits were grown under the same conditions, fed the same commercial diet and slaughtered when reached Mexican commercial weight (2.00 kg). Carcass yield, percentage of the main tissues, chemical composition of meat, shear force of cooked longissimus dorsi muscle and sensorial characteristics were evaluated. Main effects (breed and sex) and interactions were statistically analyzed. Breeds were similar on dressing percentages. However, meat from I JZ carcasses had the higher dripping losses (5.44%); NZ male had heavier skin compared to their female counterparts. Carcass composition was very similar among breeds. Mate had a higher percentage (P<0.05) of bone compared to female (17.69 and 16.18, respectively). CH female had higher inter-muscular fat than NZ female (3.99 % vs 2.08%). Meat composition was also very similar among breeds with the exception of dry matter percentage. CA females had more intra-muscular lipds than CA mate. Shear force was similar among breeds and sexes. No differences were found for aroma, flavor and general satisfaction. However, RX meat was the most tender (P<0.05) compared to lhe CA mea! (5.38 and 4.85, respectively), when sensorily evaluated. In conclusion, regardless of the production purposes of the breed (meat or fur), carcass yield and meat quality are very similar for rabbils slaughtered at 2.00 kg.
TL;DR: In view of the limitations of chemotherapy, it is imperative to develop immunoprophylactic measures against rabbit coccidiosis, including development of live-attenuated and recombinant vaccines against the parasite.
Abstract: Coccidiosis caused by Eimeria species, is a major parasitic disease of rabbits and is responsible for a high incidence of morbidity and mortalitv. The incidence of this disease in European countries in 21-60% and in India 13-64%. In commercially reared rabbits; coccidiosis occurs .in a subclinical form with growth retardation and altered feed conversion. The disease occurs in two forms, hepatic and intestinal, the latter being more common than the former. Presently, the control of rabbit coccidiosis relies almost entirely on chemical coccidiostats. However, extensive use of such drugs in commercial rabbitries has already started creating problems of drug resistance. In view of the limitations of chemotherapy, it is imperative to develop immunoprophylactic measures against rabbit coccidiosis. These include development of live-attenuated and recombinant vaccines against the parasite.
TL;DR: It seems possible to achieve slow, but simultaneous improvement of litler and growth traits with a multipletrait selection program in rabbits.
Abstract: Variance components and genetic trends were estimated for number of services/parturition (NS), parturition interval (PI), number born alive (NB), number weaned/litter born (NW), litter weaning weight (LW), 30-d individual weaning (WW) and 70-d (W70) weights and a mullipltHrait selection index (MI) in rabbits from a closed population in Botucatu, Southeast Brazil. Phenolypic values for two litter (NW and LWW), and two individual performance (WW and W70) traits were included in the index. Individual selection according to the multiple-trait index was practised for a 2.6-yr period (January 1992 through July 1994). Performance records collected for five years (July 1989 through July 1994) on 2,162 parturitions, 2,122 litters, and 10,440 individuals were included in the analyses. The general model used to estimate variance components and breeding values included the random effects of animal, maternal genetic, and permanent dam effects (for reproductive and litter traits) or common litler effects (for individual weight traits), and fixed effects of parity, parturition date, sex (for individual weight traits) and covariates of the inbreeding coefficient of the dam (for reproductive and litter traits) or of the rabbit and its dam (for individual weight traits). Inbreeding coefficients ranged from 0 to 0.36. For reproductive and litter traits, estimates of permanent dam effects ranged from 0.03 to 0.09 and estimates of direct heritability ranged from 0.02 to 0.05. The estimated genetic correlation between NS and PI was 0.73. For WW, W70, and MI, estimates of direct and maternal heritabilities and direct-maternal genetic correlation were 0.08, 0.08 and 0.28; 0.18, 0.05 and 0.76; and -0.35, 0.59 and -0.46, respectively. Estimated common litter effects for WW and W70 were 0.44 and 0.26, respectively. Estimates of direct genetic trends/yr for NS, PI, NB, NW and LW were -0.0037 ± 0.0003 services, -0.200 ± 0.030 d, 0.034 ± 0.010 young/litter, 0.039 ± 0.006 young/litter, and 35.2 ± 4.6 g, respectively. Estimates of direct and maternal genetic trends/yr were 6.74 ± 0.39 g and 1.58 ± 0.60 g for WW; 17.20 ± 1.22 g and 8.35 ± 0.71 g for W70; and 4.91 ± 0.65 and -2.34 ± 0.39 for MI. Individual weight traits showed meaningful genetic trends with multiple-trait selection, whereas reproductive and litter traits showed slight, but favourable genetic changes. lt seems possible to achieve slow, but simultaneous improvement of litler and growth traits with a multipletrait selection program in rabbits.
TL;DR: Excluding animals in late gestation, ultrasound measurement of perirenal fat thickness seems to be a useful technique for in vivo estimation of the body condition of reproducing multiparous rabbit does.
Abstract: Sixty New-Zealand×Californian multiparous rabbit does were used to evaluate the capability of a computerized ultrasound system to estimate changes in body condition at different physiological states: parturition, 21st day of lactation, weaning and 28th day of gestation. Perirenal fat weight and carcass energy concentration were significantly correlated with live weight (r = 0.58 and 0.49, respectively; P<0.001) and ultrasound measurement of perirenal fat thickness (r = 0.51 and 0.45; P<0.001). The inclusion of quadratic and cubic terms of the perirenal fat thickness as independent variables significantly increased the coefficient of determination and lowered the residual standard deviation of the models, based on the live weight of the animals, to estimate the perirenal fat weight and the carcass energy concentration (P<0.01). However, these general models tended to overestimate the perirenal fat weight and the body energy concentration of lean animals (<50 g of perirenal fat weight or 8.0 MJ kg-1 of carcass energy concentration). When specific multiple regression equations for predicting perirenal fat weight and body energy of multiparous does were developed in function of their physiological state, prediction accuracy of equations improved for rabbits at parturition (R2 = 0.72 and 0.67), 21 days of lactation (R2 = 0.84 and 0.67) and weaning (R2 = 0.76 and 0.65). No model was able to predict either perirenal fat weight or carcass energy concentration of the multiparous rabbit does at 28th day of gestation. In conclusion, excluding animals in late gestation, ultrasound measurement of perirenal fat thickness seems to be a useful technique for in vivo estimation of the body condition of reproducing multiparous rabbit does.
TL;DR: Each of heritability and repeatability estimates for milk yield and litter performance traits studied were, in general, low.
Abstract: To study the genetic and non genetic factors affecting doe milk production and preweaning litter performance, 519 litters of New Zealand White raboit were used. Sire significantly (P<0.05) affected milk yield of the first week only, while doe affected significantly (P<0.01) milk yield of most of the experimental penods except the fourth week which was insignificantly affected. Milk yield was the highest in the second parity. Season of kindling affected significantly (P<0.01) milk yield in most of the weeks of the study, except the fourth which was insignificantly affected and showed the lowest yield at summer. Litter size at birth affected significantly (P<0.01) milk yield which increased by the increase of the number of young at birth. The peak of milk production was 155.3 g/day at the third week of lactation. Sire affected insignificantly most of preweaning performances traits studied except litter size at birtfl (P<0.05). Doe affected significantly (P<0.01) litter size and weight at birth and weaning. Parity affected significantly (P<0.01) each of litter size and weight at weaning as well as preweaning mortality. Season of kindling affected rnsignificantly litter size and weight at birth and significantly (P<0.01) at weaning. Days open (from kindling to fertile mating) showed highly s1gnificant (P<0.01) effects on all preweaning litter traits studied. Each of heritability and repeatability estimates for milk yield and litter performance traits studied were, in general, low.