Epizootic Rabbit Enteropathy (ERE) is a severe disease of unknown aetiology that mainly affects post-weaning animals. Its incidence can be prevented by antibiotic treatment suggesting that bacterial elements are crucial for the development of the disease. Microbial dynamics and host responses during the disease were studied. Cecal microbiota was characterized in three rabbit groups (ERE-affected, healthy and healthy pretreated with antibiotics), followed by transcriptional analysis of cytokines and mucins in the cecal mucosa and vermix by q-rtPCR. In healthy animals, cecal microbiota with or without antibiotic pretreatment was very similar and dominated by Alistipes and Ruminococcus. Proportions of both genera decreased in ERE rabbits whereas Bacteroides, Akkermansia and Rikenella increased, as well as Clostridium, γ-Proteobacteria and other opportunistic and pathogenic species. The ERE group displayed remarkable dysbiosis and reduced taxonomic diversity. Transcription rate of mucins and inflammatory cytokines was very high in ERE rabbits, except IL-2, and its analysis revealed the existence of two clearly different gene expression patterns corresponding to Inflammatory and (mucin) Secretory Profiles. Furthermore, these profiles were associated to different bacterial species, suggesting that they may correspond to different stages of the disease. Other data obtained in this work reinforced the notion that ERE morbidity and mortality is possibly caused by an overgrowth of different pathogens in the gut of animals whose immune defence mechanisms seem not to be adequately responding.

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.

The aim of this work was to evaluate the ability of a line selected for reproductive longevity (LP) to confront productive challenges compared to a line selected during 31 generations for litter size at weaning (V). A total of 133 reproductive rabbit does were used (72 and 61 from LP and V lines, respectively). Within each line, three groups with different levels of productive effort were planned: PP9, inseminated at day 4 after the first partum and with nine kits during the second partum, and inseminated after first weaning (30 days) and with nine (PW9) or five kits (PW5) during the second partum. The reproductive performance, body condition (perirrenal fat thickness (PFT)) and lipolytic response were controlled. LP does showed greater mean live weight (LW; 1128 g; P , 0.05), PFT (10.47 mm; P , 0.05) and estimated body energy (EBE; 10.29 MJ/kg; P , 0.01) than V does at second partum. However, LP does that mated at first post partum did not significantly differ in EBE relative to V does at second partum. During the first week of lactation, dry matter (DM) intake was similar for both lines (94 and 95 g DM/kg LW 0.75 day for V and LP does, respectively). There was a significant difference in milk yield between both lines during the first week when litter size was nine (60 v. 54 g of milk/kg LW 0.75 day for LP and V does, respectively; P , 0.01), but no difference when litter size was five. Consequently, when litter size was nine, LP does showed a lower recovery of PFT (0.6 mm less; P , 0.05) than V does during the first 10 days of lactation. However, when litter size was five, LP does showed a higher LW (1210 g; P , 0.05) than V does at 10 days of lactation and a similar recovery of PFT. During the last 3 weeks of the lactation, LP does showed a higher feed intake (16 g DM/kg LW 0.75 day; P , 0.05) and milk yield (127 g/day; P , 0.001) than V does when litter size was nine, resulting in no significant differences in LW at 30 days of lactation. However, when litter size was five, both lines showed similar feed intake and milk yield, maintaining their differences in LW at 30 days of lactation (1206 g for LP does; P , 0.05). These results show that the rabbit line selected for reproductive longevity is more robust with respect to coping with productive challenges, than a line selected for reproductive intensity.

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The influence of high fat diets on several production traits of primiparous and multiparous rabbit does was studied in 246 lactations from a total of 61 crossbreed rabbit does (Californian × New Zealand). Starting with a control diet (diet C) with 26 g ether extract (EE) per kg dry matter (DM), two isoenergetic diets were formulated adding fat from vegetable sources up to 99 g EE per kg DM (diet V) or animal sources up to 117 g EE per kg DM (diet A). Digestible energy/digestible protein ratio (DE/DP) was maintained between 82 and 87 kj/g. Food intake decreased with high fat diets compared with the control diet during gestation (P ‘lt; 0·001), which implied a decrease in the DE intake (P < 0·01 and P < 0·05 for primiparous and multiparous does, respectively). Fat addition did not affect food intake of primiparous does during lactation (101·8,106·9 and 103·7 g DM per day per kg live weight (M)0·75 for C, V and A diets, respectively) but increased the DE intake (1121 kj/day per kg M°0·75 for C diet cf. 1325 for V and 1264 for A diets; P < 0·01) and reduced does' weight losses at the end of lactation (F > 0·05). However, multiparous does on C diet showed a greater food intake during the last 2 weeks of lactation (110·6 for C diet v. 101·5 and 98·9 g DM per day per kg M0·75 for V and A diets, respectively; P < 0·001). High fat diets improved significantly the productive parameters at the 21st day of lactation: increasing litter size (P < 0·01 for multiparous does) and weight (P < 0·01 and P < 0·001 for primiparous and multiparous does, respectively) and decreasing the food conversion ratio (P < 0·001). An increase of dietary fat content decreased solid food intake of litters during the last 2 weeks of lactation (P < 0·01 and P < 0·001 for primiparous and multiparous does, respectively) but only affected their solid DE intake slightly. In conclusion, high fat diets seem to improve the productivity of lactating does and their corporal condition during the first lactation.

A total of 190 rabbit females were used to evaluate five feeding programmes from 9 weeks of age to the first parturition: CAL, fed ad libitum with a control diet (C: 11.0 MJ digestible energy (DE) and 114 g digestible protein (DP)/kg dry matter (DM)) until first parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until first parturition; F, fed ad libitum with a low-energy, high-fibre diet (F: 8.7 MJ DE and 88 g DP/kg DM) until first parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until first parturition; FCF, fed with F diet ad libitum until 16 weeks of age, then C diet ad libitum until 20 weeks and then F diet ad libitum until first parturition. The rabbits were artificially inseminated at 18 weeks of age. CAL group had a higher mortality rate compared with the other groups between 9 and 12 weeks of age (34% v. 3%; P , 0.05) and during the last 3 weeks of first pregnancy (14% v. 3%; P , 0.05). The CAL and FC females presented higher BW and perirenal fat thickness (PFT) than CR females at 11 days of pregnancy (10.41 kg and 10.6 mm; P , 0.05), with F females showing medium values. The type of feeding procedure did not affect the fertility rate of young females at first artificial insemination. Differences in BW disappeared at parturition, when only CAL females presented a greater PFT than CR and FC females (10.3 mm; P , 0.05). In comparison with FCF, CAL females had smaller and thinner live born litters (22.5 kits and 2139 g, respectively; P , 0.05), with CR, F and FC females showing medium values. The low number of kits born alive for CAL females was because of their lesser total number of kits born (21.7 kits; P , 0.05) and the greater mortality of their litters at birth (113.9%; P , 0.05) compared with FCF females. Non-esterified fatty acid was higher in the blood of females fed C diet (CAL and CR) than in others at partum day (on average 10.15 mmol/l; P , 0.05). In conclusion, the ad libitum use of diets for lactating rabbit does throughout the rearing period could lead young rabbit females to present a higher risk of early death and smaller litter size at first parturition. Feed restriction or earlier use of suitably fibrous diets led females to achieve the critical BW and fat mass at first mating to ensure reproduction.

The digestion of simple sugars and oligosaccharides are considered in this chapter, in relation to rabbit feeding. The structure and digestion of starch are also described. The factors affecting starch digestibility are discussed. Moreover, the role of starch on the digestive health of suckling, growing and adult rabbits is presented.

Forty-two New-Zealand x Californian young female rabbits of 4·5 months of age were used to evaluate the use o f a computerized ultrasound system in estimating changes in body condition. In order to get a wide range of fatness, animals were randomly subjected to four food restriction regimes for 2 weeks. Female rabbits were scanned at six different back sites to estimate perirenal fat thickness, using a real-time ultrasound unit equipped with a 5·0-MHz sector probe. After scanning, all animals were weighed and slaughtered. The weights of hot carcass, cold carcass, perirenal fat, scapular fat, liver and kidneys were recorded. There was a large variation in the weight of the main fat deposits, especially for the perirenal fat (CV = 0·632), indicating its suitability for estimating changes in body condition. Ultrasound measurements of perirenal fat thickness correlated strongly with all carcass fat weight values (r= 0·692 to 0·959;P< 0·001) and the estimated carcass energy content (r= 0·777 to 0·866;P< 0·001) and seem to be more precise predictors than live weight measurements. Multiple regression equations for estimating the main fat deposit weight and estimated carcass energy content using only the live weight as an independent variable hadR2values ranging from 0·47 to 0·59. The accuracy of estimates was improved when ultrasound measurements were used in the regression model (R2values ranging from 0·81 to 0·95). Ultrasound measurement of mean perirenal fat deposit thickness at 3 cm ahead of the 2ndto 3rdlumbar vertebrae was the best predictor for perirenal fat weight (R2= 0·95;P< 0·001), total fat weight (R2= 0·93;P< 0·001) and estimated carcass energy content (R2= 0·90;P< 0·001). A validation group of 11 rabbit does was used to validate the ultrasound regression equations, showing that their mean accuracy was approximately 0·895 and 0·967 for total fat weight and estimated carcass energy content, respectively. Results suggest that ultrasound measurements of perirenal fat thickness may be an accurate method for studying changes in body condition of young female rabbits at different times.