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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

Phenolic compounds from grape products are known to possess antioxidant activity. Furthermore, grape polyphenols (anthocyanins) could be valorised as natural pigments. However, the dietary use of grape products in laying hen husbandry and its effect on egg quality traits and yolk lipid oxidation have been scarcely studied. In the present research work, egg yolk colour and Haugh units were increased with the intake of grape pomace and extract. Moreover, dietary inclusion of grape pomace at 60 g/kg increased the proportion of polyunsaturated fatty acids in the yolk and improved the yolk lipid oxidative stability during the storage of eggs, whereas no effect was obtained with grape extract. Regarding hen performance, both grape products reduced feed intake, feed conversion ratio and average egg weight, but they did not affect daily egg production and mass. Feeding grape pomace, at 60 g/kg, and grape extract, either at 0.5 or 1.0 g/kg, decreased protein digestibility. In conclusion, the addition of grape products in the diet of laying hens improved the egg quality but reduced feed intake and egg weight. Dietary grape pomace showed higher antioxidant potential in egg yolk than grape extract., Ministerio de Economía, Comercio y Empresa (España), Junta de Castilla y León, Depto. de Genética, Fisiología y Microbiología, Depto. de Producción Animal, Fac. de Ciencias Biológicas, Fac. de Veterinaria, TRUE, pub

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

Industrial processing of livestock, poultry and fish produces a large amount of waste in a solid or liquid form that can either be destroyed or be used to make compost, biogas or other low-added value products. However, the by-products from animal processing industries have a potential for conversion into useful products of higher value, such as protein hydrolysates, with interesting applications in animal feed. Low amounts of animal protein hydrolysates included in aqua-feeds may enhance growth rate and feed conversion of farmed fish and crustacean. Animal protein hydrolysates may also be incorporated in diets to enhance the nonspecific immunity of fish. As well, these hydrolysates can be used as a good source of amino acids for newly weaned animals. Protein hydrolysates from animal by-products including antimicrobials, antioxidants, opioid-like and/or other interesting bioactive molecules have promising and interesting applications on companion and production animals. By-products from animal processing industries are therefore a promising source of bioactive peptides of considerable interest for animal care, always within the framework of the existing legislation. Possible drawbacks and future trends of the use of animal by-products and/or production of protein hydrolysates from those materials are also discussed., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

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

Grape seed extract and grape pomace are rich sources of polyphenols. The aim of this study was to evaluate the release of polyphenols, the solubilisation of carbohydrate, and the antioxidant capacity of these grape by-products after enzymatic reaction with carbohydrases (cellulolytic and pectinolytic activities) and tannase for 24 h. The use of tannase in these by-products, and pectinase in grape pomace changed the galloylated form of catechin to its free form, releasing gallic acid and increasing the antioxidant activity. In grape pomace, cellulase treatment was not efficient for phenolic release and antioxidant activity improvement. The addition of carbohydrases to grape pomace, either alone or in combination, degraded the cell wall polysaccharides, increasing the content of monosaccharides. These results provide relevant data about the potential of pectinase, tannase and combinations of enzymes on the release of polyphenols and monosaccharides from grape by-products, improving the antioxidant capacity and the nutritional value., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

Weaning is considered a stressful period for rabbits caused by abrupt changes of diet and environment. An immature immune system together with a transient decrease of nutrient digestibility places the animal in adverse conditions where digestive pathologies might take place. In recent years the European ban on antibiotic type growth promoters in animal feeds has even complicated weaning management for farmers because of the widespread and incidence of emerging animal diseases. Since the first outbreaks in 1997 the epizootic rabbit enteropathy (ERE) has become a threatto the industry as it can cause between 20 and 70% of mortality and up to 100% morbidity in European rabbit commercial farms. Although the aetiology ofthis disease remains unknown, proliferation of Clostridium perfringens could be a consequence of ERE and might be associated to the high mortality caused by this disease. Although, several antibiotics have been proven to be efficient against ERE, there is a need to find alternative solutions to control the disease in order to fulfil current EU legislation. Among them, nutritional management has become a priority, given its importance on digestive diseases. The present work summarises recent research related to the feed composition and management of young rabbits in farms affected by ERE, aiming to provide useful guidelines for nutritionists towards a preventive nutrition against this disease. Data dealing with maternal and environmental effects on ERE incidence and mortality are also discussed., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

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

The aim of this paper was to study the effect of the intensive breeding system (IBS: insemination 4 d postpartum and weaning age at 25 d) vs. the semi-intensive breeding system (SIBS: insemination 11 d post-partum and weaning age at 35 d) on lactating does’ performance and the combined effect of the type of farm hygiene (cleaned and disinfected or not) on the performance of growing rabbits from weaning until 56 d of age. A total of 58 New Zealand×Californian rabbit does (29/reproductive rhythm) and 168 young rabbits per combination weaning age×type of farm were selected at random over two consecutive reproductive cycles. Mortality during lactation presented higher values (P=0.067) in young rabbits weaned at 35 d than in those weaned at 25 (19.1 vs. 9.60%). In the fi rst cycle, the number of kits weaned per litter was similar for both reproductive rhythms (7.89 and 8.01 for IBS and SIBS, respectively), whereas in the second cycle, the number of rabbits weaned was lower in rabbit does that weaned their litters later (6.90 vs. 9.06; P=0.049). Weight at parturition and at weaning, fertility, parturition interval, numerical productivity and the number of young rabbits born dead and weaned were not affected by treatments. The fattening mortality was higher in the second cycle than in the fi rst (20.2 vs. 14.5 %, P=0.051), in the farm without cleaning and disinfection between cycles (20.0 vs. 14.2%, P=0.032) and in the animals weaned at 35 d than at 25 d (20.0 vs. 14.7 %, P=0.063). Animals weaned at 25 and 35 d of age both had a peak of mortality around two weeks after weaning. The average weight of rabbits at 56 d was not signigicantly different between the animals weaned at 25 or 35 d (1805 vs. 1787 g, respectively; P=0.64). However, the feed effi ciency in the whole fattening period was higher in young rabbits weaned at 25 d than in those weaned at 35 d (0.392 vs. 0.298 g/g; P<0.001)., Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

The aim of this work was to study the effect of protein source / availability on the intestinal microbiota, digestive traits and nutritional performance of early-weaned rabbits. The effects of supplemental antibiotics in the drinking water were also evaluated. Four isoenergetic and isofibrous diets were formulated: a control diet with a high protein (207 g/kg dry matter (DM)) and lucerne hay content (HPHL), a diet with low crude protein (CP) (179 g/kg DM) and high lucerne hay content (LPHL) and low protein diets in which the lucerne hay in diet LPHL was replaced partially (LPML) or totally (LPLL) with soya-bean protein concentrate. Rabbits, weaned at 25 days (52 per diet), were fed the experimental diets for a 2-week period and thereafter received a commercial diet until 56 days of age. The incidence of mortality was investigated using 70 animals per diet without supplemental medication. The profile of the ileal microbiota was studied at 35 days of age in rabbits treated (18 per diet) or not (12 per diet) with antibiotic. As expected, supplementation with antibiotics effectively reduced fattening mortality rate and microbial biodiversity. However, lowering of also the dietary CP content led to a reduction in the mortality rate ( P < 0.05), both in animals treated with (by 80%) or without (by 39%) antibiotics. In addition, there was a reduction ( P < 0.05) in the frequency of Clostridium perfringens in non-medicated animals. Neither jejunal morphology nor growth performance, over the whole fattening period, was affected by dietary CP content of the experimental diets. However, with HPHL, feed efficiency was higher (by 4.8%; P < 0.01) than with LPHL diets. Substitution of lucerne hay with soya-bean meal in low protein diets did not affect apparent faecal or ileal digestibility of DM and CP. However, the ileal digestibility of cystine, alanine, aspartic acid, and proline was lowered ( P < 0.05) with increasing substitution by soya bean. Nevertheless, ileal CP flow, inc, Comisión Interministerial de Ciencia y Tecnología (CICYT), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub