The effect of source of carbohydrate on gut histology, digestion efficiency, and growth performance in early-weaned (25 d) rabbits at the starter period (25 to 39 d) was investigated. Six diets were factorially arranged to study the effect of partial substitution of starch (0, 25, or 50%) by lactose at two levels of fiber (30 or 36% NDF). Diets were formulated to meet or exceed essential nutrient requirements of growing rabbits. A feeding trial was conducted to measure the effect of treatments on growth performance in 252 rabbits that were fed the experimental diets in the starter period and thereafter received a common feed until 60 d of age. Fecal apparent digestibility was determined at 35 d of age in nine animals per diet. The four diets with extreme lactose content were used to determine ileal apparent digestibility of starch and lactose (nine replicates per diet), weights of stomach and cecum, stomach pH, cecal fermentation traits, amylase and disaccharidase activities (10 animals per diet), and jejunal morphology (six animals per diet). Weaning increased (P < 0.001) amylase activity by 59% but decreased (P < 0.001) maltase, sucrase, and lactase activities by 30, 48, and 72%, in parallel with a reduction of villus height by 19%. Dietary NDF level did not affect either jejunal morphology or sucrase and lactase activities but increased amylase (P = 0.05) and maltase (P < 0.001) activities by 22 and 92%, respectively. Substitution of starch by lactose had no effect on jejunal morphology or enzymatic activity. Ileal lactose and starch digestibility were not affected by dietary NDF or lactose level and averaged 73.8 and 90.8%, respectively. Substitution of starch by fiber and lactose affected ileal flux of starch plus lactose (by -0.5 and +1.7 g/d) and cecal pH (by +2.1 and -2.8%, respectively). Fecal NDF digestibility was relatively low (23.1% on average) and was not affected by treatments, whereas that of lactose and starch was almost complete. An increase of dietary NDF level led to an impairment of ADG and feed efficiency in the starter (P < 0.002) and in the overall (P < 0.03) fattening period. Substitution of starch by lactose linearly decreased (P < 0.001) feed efficiency in the starter period and linearly increased (P < 0.001) diarrhea incidence in the fattening period. The results indicate that digestive capability of early-weaned rabbits is limited and should be taken into account to establish optimal levels and sources of carbohydrates in the starter diet.

-Four diets based on different vegetal protein concentrates: soya bean meal 48 (SB48 diet), soya bean protein concentrate (SB61 diet), sunflower meal 36 (SF36 diet) and a combination of soya bean meal 48 and potato protein concentrate (SB48-P77 diet) were formulated for the starter period (25-39 days) in early weaned rabbits (25 days of age). These sources of protein accounted for 30% of the total dietary crude protein (CP) content. All diets were formulated to be isonutritive and to meet or exceed all the essential nutrient requirements of growing rabbits. A feeding trial was conducted to measure the effect of the treatments on growth performance in 204 rabbits that were fed ad libitum the experimental diets in the starter period and thereafter received a common feed until 60 d of age. Faecal and ileal apparent digestibility of dry matter (DM) and CP (9 and 7 replicates, respectively) were determined at 35 d of age. The weights and pH of the stomach and caecal contents, ammonia concentration in the caecum and jejunal morphology were also determined (11 rabbits per diet). The treatments did not affect faecal DM and CP digestibility. However, the source of protein affected ileal digestibilities of DM and CP (P < 0.04), which were around 14 and 7% higher for SB61 and SF36 diets, respectively, than for the SB48 diet, whereas the values obtained for the SB48-P77 diet were intermediate. The ileal flux of CP and the N-NH 3 caecal concentration were (P = 0.08 and 0.05, respectively) affected by the source of protein. The highest values were observed in animals fed the SB48-P77 diet, increasing by around 25 and 35%, respectively, compared to the other three diets. The treatments had no effect on digestive traits and jejunal morphology. The differences in ileal digestion efficacy among treatments led to differences (P = 0.008) in food efficiency the first week after weaning, which was higher (10%, as average) in animals fed the SB61 diet than that observed for animals fed the SB48 and SB48-P77 diets, whereas the value obtained for SF36 was intermediate. In this period, the type of diet tended (P = 0.08) to affect daily gain and food efficiency, with the lowest values obtained for the SB48 diet. The treatments had no effect on mortality in the first two weeks after weaning. However, mortality in the whole fattening period was affected by protein source (P = 0.03), since it was higher in animals fed the SB48-P77 diet after weaning than the animals fed the other three diets (34.6 vs. 16.7%, respectively). In conclusion, SF36 and SB61 are the sources of protein that led 461 * Corresponding author: cdeblas@pan.etsia.upm.es Anim. Res. 52 (2003) DOI: 10.1051 to the best growth performances and the lowest mortality rate. The higher efficiency obtained for these feeds might be mainly related to its higher ileal (CP) digestibility.461-471  INRA, EDP Sciences,sources of protein / digestion / growth performance / early weaning / rabbits Résumé -Effet de la source protéique sur la digestion et la croissance de lapereau...

The role of gut barrier against pathogens and its interaction with dietary factors in weaned rabbits affected with digestive disorders, especially epizootic rabbit enteropathy is reviewed. This interaction was studied identifying nutritive factors that influence gut barrier function of mucosa. It was examined the morphology, and enzyme activity of mucosa and the gut associated immune system. Besides, it was characterized the substrate that reaches the caecum and its capacity to favour pathogen bacteria growth, by reviewing the effect of diet on ileal digestibility of nutrients, transit time and microbiota population. The nutritional factors which affect health of early weaned rabbits are level and type of both fibre and protein. The optimal dietary level of insoluble fibre to minimise mortality is 30-32%. Furthermore, a moderate inclusion of soluble fibre (12%) improves mucosa integrity and decreases mortality and the frequency of detection of Clostridium perfringens and Campylobacter spp in the caecum. The reduction of ileal nitrogen flow had a positive effect on pups viability and frequency of detection of C. perfringens. Furthermore, dietary supplementation with 1% of glutamine reduced fattening mortality, the frequency of detection of C. perfringens, and Helicobacter spp, and diminished the counts of Eimeria spp at the jejunum. In conclusion, a correct diet formulation may help to limit the epizootic rabbit enteropathy incidence in weaned rabbits.Additional key words: fibre, gut barrier function, protein, weaning, young rabbits. ResumenRevisión. Nuevas tendencias en alimentación de conejos. Efecto de la nutrición sobre la salud intestinal En este trabajo se revisa el papel de la barrera intestinal frente a patógenos y su interacción con factores de la dieta en gazapos destetados afectados por enteropatía epizoótica. Para ello, se identificaron los factores nutritivos que influyen en la funcionalidad de la barrera intestinal de la mucosa digestiva (morfología, actividad enzimática y actividad del sistema inmune asociado a la mucosa). Además, se ha caracterizado el sustrato alimenticio que alcanza el ciego y su capacidad para favorecer el crecimiento de bacterias patógenas, revisando el efecto de la dieta sobre la digestibilidad ileal de nutrientes, el tránsito digestivo y el tipo de flora intestinal. Los factores nutricionales involucrados incluyen nivel y tipo de fibra y proteína. El contenido óptimo de fibra insoluble en el pienso para minimizar la mortalidad es un 30-32%. Además, una inclusión moderada de fibra soluble (12%) mejoró la integridad de la mucosa y redujo la mortalidad y la frecuencia de detección de Clostridium perfringens y de Campylobacter spp en el ciego. Un descenso del flujo ileal de nitrógeno tuvo también un efecto positivo sobre la viabilidad de los gazapos y la frecuencia de detección de C. perfringens. La suplementación del pienso con un 1% de glutamina redujo la mortalidad en cebo y la frecuencia de detección de C. perfringens y Helicobacter spp, y disminuyó los conteos de Ei...

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-In this study we investigated the influence of the reproductive system on doe reproductive performance. Two experimental treatments were compared using 36 cages per treatment over an 8-month production period. In the intensive system (IS) rabbit does were mated 4 d after parturition and the litters were weaned at 25 d of age, whereas in the control system (CS) the rabbit does were mated 11 d after parturition and the litters were weaned at 35 d of age. In both systems, the does that failed to mate, conceive or lost their pups were immediately given the opportunity to remate. Initially seventy-two New Zealand × Californian does were assigned to the treatments and used to determine the reproductive traits. Early mating of rabbit does associated with 25-d litter weaning (IS) allowed a shorter parturition interval (39.9 vs. 44.4 d, P = 0.0001) and a higher prolificacy (9.07 vs. 8.11 young rabbits born alive per litter, P = 0.06), litter size at 21 d (8.24 vs. 7.51, P = 0.06) and at weaning (8.21 vs. 7.42, P = 0.05) and tended to reduce the number of young rabbits born dead (0.52 vs. 0.94, P = 0.10) as compared to the animals in the CS treatment. Consequently, numerical productivity increased from 61.6 to 73.4 young rabbits per cage and year (P = 0.003). The intensively bred does had a lower receptivity to the male at the first mating (54 vs. 86.9%, respectively), but 88% of these does accepted mating within 7 d after parturition. Fertility was high, above 80%, in all the matings. The treatments did not affect either the body weight (4301 g as average) or the mortality of the rabbit does (14.6%) and the mortality of the young rabbits during lactation (11.8%). Feed efficiency increased from 0.241 to 0.309 g of young rabbits weaned per g of feed when the remating interval was longer but these results cannot be compared because of the parallel increase in the age and weight of the young rabbits at weaning. This study indicates that, in the conditions of reproductive management used, the numerical productivity can be increased through earlier mating and weaning. However, more information is needed about the effect of this system on young rabbit performance after weaning, and about the possibility of increasing the receptivity of rabbit does at 4 d by using bio-stimulation methods.reproductive performance / remating interval / early weaning / early mating / doe rabbits Anim. Res. 51 (2002) 517-523  INRA, EDP Sciences, 2002 DOI: 10.1051/animres:2002037Résumé -Effet de l'intervalle d'accouplement et de l'âge au sevrage sur les performances de reproduction chez la lapine. Ce travail a eu pour but d'étudier l'influence de deux intervalles d'accouplement (4 ou 11 j après le vêlage) associés à différents âges au sevrage (25 et 35 j, respectivement) sur les performances de reproduction de la lapine. Dans ce but, deux traitements expérimentaux ont été comparés en utilisant 36 cages par traitement pendant une période de production de 8 mois. Initialement, soixante-douze lapines de race Néo-Zélandaise × Californienne ont...