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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., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

An experiment was conducted to study the effect of a reduction in dietary sodium content on performance and nutrient digestibility, in rabbits weaned at 25 days of age. Two diets with the same composition and only differing in the supply of sodium chloride content (0.5 or 0%) were used. A reduction on the dietary sodium content from 2.7 to 0.6 g kg–1 DM decreased the ileal and faecal apparent digestibility of dry matter, crude protein and the ileal apparent digestibility of every amino acid studied with the exception of the phenylalanine, and reduced daily weight gain, feed intake and feed efficiency. These results indicate that a reduction of the dietary sodium content up to 0.6 g kg–1 DM results excessive and insufficient to assure a correct absorption of nutrients and to maintain the growth performance in growing rabbit., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

An experiment was conducted to determine the effects of source of protein (soybean vs sunflower meal) and enzyme supplementation (no enzyme vs protease addition vs protease + xylanase addition) on digestion and growth traits of rabbits. Treatments were arranged factorially in six isonutritive diets. Two hundred and forty rabbits weaned at 25 or 35 days were used to measure dry matter and crude protein apparent ileal digestibility of diets at 35 or 45 days of age, respectively. Another one hundred and eighty animals weaned at 35 days were fed ad libitum in individual cages during four weeks to determine fattening performance. Source of protein did not affect digestion efficiency or feed conversion rate in the whole fattening period, but animals fed soybean meal-based diets showed higher feed intake, grew faster and had higher mortality than those fed sunflower meal-based diets. Addition of enzymes increased ileal apparent digestibility, especially in youngest animals when supplements contained xylanase besides protease activity. Enzyme supplementation did not affect any of the growth traits studied, but decreased fattening mortality in sunflower meal-based diets., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

The effects of a reduction in the sodium content from 2.6 to 1.6 g/kg DM in diets with similar electrolyte balance on fattening performances and ileal apparent digestibility of nutrients were investigated in early weaned rabbits. Two diets containing 17.9% DM of crude protein, with the same composition and only differing in sodium chloride content (0.5 and 0.2%) were given to rabbits weaned at 25 days to measure fattening performance (46 rabbits per diet), and apparent ileal digestibility (AID, 14 rabbits per diet) of DM, crude protein (CP) and amino acids (AA). Neither AID of DM nor AID of CP, which amounted 47.4 and 60.9% as average respectively, were affected by the dietary sodium content. The effect of a decrease in dietary sodium concentration on the AID differed among amino acids, as a reduction was observed for cystine (by 11%; P0.10) were detected for the other amino acids. A reduction of dietary sodium content did not affect daily weight gain, feed intake and feed efficiency (46.7 g/d, 76.7 g/d and 0.609 as average, respectively) neither during the first two weeks after weaning when the experimental diets were used, nor when the whole fattening period was regarded. The results of this experiment indicate that is possible to reduce the current dietary sodium recommendations for fattening rabbits to 1.6 g/kg DM during the first two weeks after weaning, without impairing either the fattening performances or the ileal digestibility of DM and CP. In addition, this study indicate that the level of sodium in the diet affects the gut absorption of methionine and cystine and several non-essential AA., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

In the European context, the new legislation to avoid mineral contamination and the ban on antibiotics as growth promoters has led to the defi nition 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 fl ow to the caecum increases mortality rates during fattening by favouring the growth of potential pathogenic bacteria. Accordingly, feeding strategies to reduce ileal nitrogen fl ow have been reviewed. A large reduction of dietary protein level might have negative consequences on growth performances and mortality. In order to formulate balanced lowprotein 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., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

The effect of dietary supplementation with 1% l-glutamine and a combination of 1% l-glutamine and 0.5% l-arginine on intestinal health was examined in weaned rabbits. A basal diet was formulated to meet nutrient recommendations. Another 2 diets were formulated by adding 1% (as-fed basis) Gln or a mixture of 1% (as-fed basis) Gln + 0.5% (as-fed basis) Arg (Gln-Arg) to the basal diet. In Exp. 1, a total of 357 rabbits were blocked by litter and assigned at random to the experimental diet to determine mortality (119 per diet) and growth performance (35 per diet; from weaning at 25 to 56 d of age). Rabbits were fed the experimental diets for a 2-wk period and thereafter received a commercial diet. Rabbits weaned at 25 d (blocked by litter and assigned at random to diets) were slaughtered at 35 d and used to determine apparent ileal digestibility of DM, CP, and AA (Exp. 2, a total of 60 rabbits), intestinal morphology, N-aminopeptidase and myeloperoxidase intestinal activity, the expression of PPARgamma at the ileum and kidney, serum immunoglobulin in healthy and sick rabbits (Exp. 3, a total of 24 rabbits), and ileal and cecal microbial composition by PCR-RFLP (Exp. 4, a total of 45 rabbits). Dietary treatment did not affect ADG, ADFI, or G:F, during the entire fattening period. Supplementation with Gln reduced mortality during the first 2 wk and the whole fattening period from 18.5 to 8.4% (P = 0.023) and from 31.9 to 20.2% (P = 0.039), respectively, whereas no effect was detected for Arg supplementation. Among all the variables studied, the reduction on mortality due to Gln was related to a reduced intestinal colonization (Eimeria lesions) and changes on microbial ecosystem in the ileum and cecum, reducing the frequency of detection of Clostridium spp. (from 86.7 to 33.3%, P = 0.003) at the ileum, and Helicobacter spp. at the ileum (from 86.7 to 46.7%, P = 0.003) and at the cecum (from 86.7 to 46.7, P = 0.028), whereas no effect was detected for Arg supplementation. I, Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub