Nutritive value and anthelmintic effect of sainfoin pellets fed to experimentally infected growing rabbits

Alternative strategies to synthetic chemical drugs are needed in livestock and are a key issue in organic farming today. This study aimed at examining the potentialities of sainfoin, a legume rich in condensed tannins, as a nutraceutical that combines nutritive and antiparasitic effects in rabbits. To test the effect of infection with a helminth (I: infected groups; NI: not infected groups) and the effect of substituting 40% of the alfalfa in a control diet (C) with sainfoin (diet S), four groups of 16 weaned rabbits were arranged according to a 2×2 bifactorial design. The sainfoin diet differed from the control by its tannin concentration (1.8% v. 1.0% tannic acid equivalent) and its ADL concentration (84 v. 43 g/kg). For each diet, 16 rabbits were infected with 2125 third-stage larvae of Trichostrongylus colubriformis. Growth, feed intake, feed conversion ratio and nematode faecal egg counts (FECs) were controlled for 6 weeks. A digestibility trial was performed. After necropsy, adult worms and eggs in utero per female were counted and egg-hatching rate calculated. Growth tended to be lower for S groups than for C groups (38.2 v. 39.5 g/day; P=0.06). Feed intake was higher for S groups compared with C groups (+5.2 g dry matter/day; P<0.01), as was the feed conversion ratio (3.2 v. 2.9; P<0.001), probably in relation to the dietary ADL level. Protein digestibility was reduced in S groups compared with C groups (-6.0 points; P<0.001), probably associated with the effect of the tannin concentration. Digestibility of hemicelluloses was reduced in infected rabbits compared with non-infected ones (-5 points; P=0.01). Using the substitution method, the digestible energy of dehydrated sainfoin pellets used as raw material was calculated at 11.12 MJ/kg and digestible proteins at 110 g/kg. The infection did not produce any clinical signs of digestive disorders. No differences were observed according to the diet, neither in the number of adult worms (972; P=0.50), the number of eggs in utero per female (14; P=0.95), nor FEC (400 eggs/g; P=0.57). In contrast, the rate of faecal egg hatching in the S group tended to be lower than in the control (58.3% v. 85.2%; P=0.08). In conclusion, sainfoin seems to fit nutritive requirements for rabbits, supplies a large quantity of fibre and particularly lignins, and limits the development of nematode eggs in faeces.

Effect of inclusion of sunflower hulls in the diet on performance, disaccharidase activity in the small intestine and caecal traits of growing rabbits

A basal diet was formulated to meet the nutrient requirements of growing rabbits. Another diet was formulated by substituting 152 g/kg of the basal diet with sunflower hulls (SH diet). One hundred and sixty-eight weaned 30-day-old rabbits were given these diets and finishing performance was recorded. Eighty animals were used to study the effect of SH inclusion on caecal fermentation traits at two ages (5 and 35 days after weaning) and disaccharidase activity in the small intestine at 35 days after weaning. Inclusion of SH in the diet reduced growth rate by proportionately 0·056 in the first 2 weeks after weaning (P 0 ×001), but had no effect from 14 to 65 days after weaning. Accordingly, daily gain was lower by a factor of 0·035 over the whole finishing period (P 0×01). There was no effect of treatment on food intake during the 14 days after weaning, but SH inclusion tended to increase it from this time onwards ( +0·026; P = 0 ×06) and over the whole finishing period ( + 0·018; P = 0 ×09). This effect was parallel to a 0·09 proportional decrease in the weight of caecal contents (P 0 ×01) observed in animals of 2 kg live weight. Food efficiency was lower by a factor of 0·05 (P 0×001) in all the periods considered when SH was included in the diet. Mortality rate (6%) was not affected by treatment nor was caecal pH or caecal concentrations of volatile fatty acids and ammonia nitrogen either at 5 days (5×75, 72×7 mmol/l and 16×6 mmol/l, respectively) or at 35 days after weaning (5×70, 74×3 mmol/l and 9 ×7 5 mmol/l, respectively). Inclusion of SH increased sucrase specific activity at the ileum by a factor of 0·47 (P 0×01) but had no effect on maltase specific activity at the jejunum or ileum or on sucrase specific activity at the jejunum. In conclusion, SH included at moderate levels (150 g/kg) in the diet reduced accumulation of digesta in the caecum, which increased voluntary food intake but impaired growth rate and food efficiency. Inclusion of SH did not affect caecal fermentation or mortality.

The effect of the quality of dietary lignocellulose on digestion, zootechnical performance and health of the growing rabbit

The aim of this study was to evaluate the performance and digestive response of the growing rabbit according to a change in the nature of the lignocellulose (ADF), without a change in the ADF level. Three diets with a linearly decreasing lignin/cellulose ratio (ADL/cellulose = 0·8; 0·4; 0·2; respectively LC8, LC4, LC2) were given to a total of 162 rabbits per diet, from weaning till slaughter weight. A reduction of the ADL/cellulose ratio led to a lower food intake (LC8 v LC2: -11%), associated with a lower daily weight gain (-6% for LC2). Mortality and morbidity rate was significantly greater (+50%) for LC2 and LC4 diets compared with the LC8. Thus, the health risk index (morbidity + mortality) increased by 20 units for LC4 and LC2 compared with LC8 diet. In parallel, rate of passage was slower (mean retention time 4·5 h greater,P= 0045) with LC4 and LC2 diets. Dry-matter digestibility was slightly affected, whereas protein digestion was favoured with low ADL/cellulose ratio. It is recommended that a minimum lignin supply (about 6 g/day) is adopted as well as a minimum dietary lignocellulose to ensure growth performance and health of the growing rabbit.

Nutritive value of co-products derived from olivecake in rabbit feeding

<p>Olive cake is one of the main agro-industrial co-products in the Mediterranean area of Spain, with high availability almost all year round. In addition, most of the product is dehydrated, which increases its interest in monogastric species such as rabbits. Nineteen samples from various Spanish oil mills using different processing methods were analysed for their chemical composition and in vitro digestibility. The average composition was [in dry matter (DM) basis]: ash (9.64%), neutral detergent fibre (52.0%), acid detergent fibre (36.8%), acid detergent lignin (19.1%), crude protein (CP) (11.3%), insoluble neutral (8.0%) and acid detergent crude protein (5.15%), ether extract (10.9%) and gross energy (21.9 MJ/kg). DM and CP in vitro digestibility were, on av., 53.4 and 41.4% respectively. High variability was observed among the samples for most of the traits studied. Fibrous fractions were highly correlated among them and negatively with ether extract content, whereas CP was little related to other feed components. A stepwise regression analysis allowed us to determine regression equations to predict DM and CP in vitro digestibilities from chemical composition (R2=0.80 and 0.91, respectively). As regards the current results, olive cake has potential use for rabbits as a source of insoluble fibre and lignin. Crude samples (not oil extracted) combined with sieving to retain the smaller particles have an additional interest, because of their higher energy value and significant supply of high quality fat.</p>

Dietary fibres in the nutrition of the growing rabbit and recommendations to preserve digestive health: a review

The importance of dietary fibre fractions in animal feeding is due to its influence on the rate of passage, mucosal functionality and its role as substrate for gut microbiota that relates to performance and digestive health. The complexity of the physical structure and chemical composition of polysaccharides in plant cell walls explains the wide and different physiological effects of this large range of fibre fractions. Our review will first briefly consider the definition and structure of the different classes of fibres and of cell wall constituents, followed by a description of some analytical methods employed for monogastric feeds. Second, the nutritional role and impact of fibre intake on digestive health will be described for the growing rabbit with an extensive analysis of previous studies performed without antibiotics. The fibres in rabbit feed are essential for reducing the risk of digestive trouble after weaning, and the requirements are defined in terms of the quantity and quality of the fibre fractions as follows: a minimal dietary level of lignocellulose 'ADF' (18%) and lignins (>5%), balanced with a maximum quantity of digestible fibres 'DgF' (ratio DgF/ADF below 1.3). Soluble fibres, defined as the difference between total dietary fibre and NDF, are quickly fermented and digested by the rabbit. However, their impact on digestive health is still questioned.

Effect of a high fibre intake on the resistance of the growing rabbit to an experimental inoculation with an enteropathogenic strain ofEscherichia coli

Response to an experimental infection with an enteropathogenicE. coliO103 strain (EPEC) was assessed in growing rabbits given a high or a low dietary fibre diet (200 and 120 g acid-detergent fibre per kg respectively for high ‘HF’ or low ‘LF’ fibre diet). The two experimental diets, differing in fibre level but not fibre quality, were given ad libitum from 21 days of age to two groups of 12 litters of nine pups, weaned at 28 days (trial 1) and caged collectively. At 42 days of age, the two groups were divided in two subgroups (i.e. four groups of 18 animals), inoculated or not with an EPEC O103 strain. Two further groups of 48 rabbits (trial 2) were given LF and HF diets from 28 days (weaning) to 70 days, and were individually housed to control precisely the food intake. Reducing the fibre level led to a lower post-weaning food intake (64 v. 85 g/days in the period from 28 to 42 days of age,P< 0·001) and digestible energy intake (0·75v.. 0·86 MJ/day,P< 0·001), causing a lower growth (proportionately 0·088 lower,P< 0·001). At 42 days of age, only 17% of rabbits had a detectable caecal saprophyteE. coliflora (over 102colony-forming units (CFU) per g, trial 1). Inoculating 6-week-old rabbits with EPEC led to moderate levels of mortality (26%). Health risk index (mortality + morbidity) was numerically higher in LF compared with HF groups (P= 0·12). The acute phase of the colibacillosis was between 3 and 10 days post inoculation. From days 7 to 14 post inoculation, a significantly higher frequency of rabbits having a high faecal excretion ofE. coli(> 105CFU per g) was found in LF than in HF rabbits (respectively 65 v. 26·7%,P= 0·04). The caecal pectinolytic flora reached 108CFU per g at 42 and 65 days of age, and was not affected by diet or EPEC challenge. In 42-day-old rabbits the caecal volatile fatty acid concentration was higher in HF than in LF groups (respectively 79 v. 60 mmol/l,P< 0·05), while the caecal pH was slightly lower (respectively 5·93 v. 6·09,P< 0·01). At 65 days of age, rabbits resistant to the inoculation showed a similar fermentation pattern and fibrolytic flora level to non-inoculated animals. Caecal ammonia level was not affected either by age, diet orE. colichallenge (mean = 12·1 mmol/l). From these results, we conclude that a high fibre intake improved the resistance of the growing rabbit to a specific enteropathy, in association with a higher caecal fermentative activity and lower caecal pH.

Inter-relationship of microbial activity, digestion and gut health in the rabbit: effect of substituting fibre by starch in diets having a high proportion of rapidly fermentable polysaccharides

Caecal microbial activity, digestion and gut health were analysed in the young rabbit, in response to fibre substitution by starch, in diets with high proportions of rapidly fermentable polysaccharides (pectins+hemicelluloses:acid-detergent fibre (ADF) ratio of 1.7). A range of five diets corresponding to a 60 % linear reduction of the ADF level (230 to 92 g ADF/kg) without changes in the fibre quality, and to a corresponding linear increase in dietary starch, was given ad libitum to young rabbits from 18 d until 70 d of age. A one half reduction of the ADF level resulted in a sharp increase in energy digestibility (+25 units), associated with a lower feed intake (-35 %) and to an increase of the mean retention time (+6 h) in the whole digestive tract. Despite large variations in the fibre intake (20 to 59 g ADF/d), the fibre digestive efficiency remained similar among the five diets. Starch ileal concentrations were low after 4 weeks of age (<5 %), and variations with age were significant when the dietary starch level was over 19 %. A 65 % lower biomass production was measured when the ADF level progressed from 230 to 165 g/kg, and no precise relationship was found with fermentative activity. Reducing the fibre intake led to a linear decrease of caecal volatile fatty acids concentrations, and to higher pH and NH3 levels. An increased occurrence of mortality by diarrhoea was registered with the lowest fibre intake. It can be concluded that a sufficient supply of fibre, with high proportions in rapidly fermentable polysaccharides, stimulates the maturation of microbial activity and reduces the occurrence of diarrhoea.