Extracts of Apricot (Prunus armeniaca) and Peach (Prunus pérsica) Kernels as Feed Additives: Nutrient Digestibility, Growth Performance, and Immunological Status of Growing Rabbits

This study assessed the effects of the kernel extracts of apricot (AKE; Prunus armeniaca) and peach (PKE; Prunus pérsica), and their mixture (Mix) on growth efficiency, feed utilization, cecum activity, and health status, of growing rabbits. Weaned male New Zealand White rabbits at six weeks old [n = 84, 736 ± 24 SE g body weight (BW)] were randomly allotted to four dietary groups. The first group received no feed additives (control), the second and third groups received 0.3 mL/kg BW of AKE and PKE, respectively, and the fourth group received a mixture of AKE and PKE (1:1) at 0.3 mL/kg BW (Mix). Results indicated that 2(3h)-Furanone, 5-Heptyldihydro was found in abundance in both extracts, while 1,1-Dimethyl-2 Phenylethy L Butyrate and 1,3-Dioxolane, and 4-Methyl-2-Phenyl- were the most components detected in AKE and Cyclohexanol and 10-Methylundecan-4-olide were found in abundance in PKE. All the experimental extracts enhanced (p < 0.05) the growth performance, cecal fermentation parameters, and cecal L. acidiophilus and L. cellobiosus count, while PKE and the mixture treatments presented the highest (p = 0.001) total weight gain and average weight gain without affecting the feed intake. Rabbits that received the mix treatment had the highest (p < 0.05) nutrient digestibility and nitrogen retained, and the lowest (p = 0.001) cecal ammonia concentration. All the experimental extracts enhanced (p < 0.05) the blood antioxidant indicators (including total antioxidant capacity, catalase, and superoxide dismutase concentrations), and immune response of growing rabbits. In general, fruit kernel extracts are rich sources of bioactive substances that can be used as promising feed additives to promote the growth and health status of weaned rabbits.

Maximum levels of cross-contamination for 24 antimicrobial active substances in non-target feed. Part 12: Tetracyclines: tetracycline, chlortetracycline, oxytetracycline, and doxycycline

The specific concentrations of tetracycline, chlortetracycline, oxytetracycline and doxycycline in non-target feed for food-producing animals, below which there would not be an effect on the emergence of, and/or selection for, resistance in bacteria relevant for human and animal health, as well as the specific antimicrobial concentrations in feed which have an effect in terms of growth promotion/increased yield were assessed by EFSA in collaboration with EMA. Details of the methodology used for this assessment, associated data gaps and uncertainties are presented in a separate document. To address antimicrobial resistance, the Feed Antimicrobial Resistance Selection Concentration (FARSC) model developed specifically for the assessment was applied. The FARSC for these four tetracyclines was estimated. To address growth promotion, data from scientific publications obtained from an extensive literature review were used. Levels in feed that showed to have an effect on growth promotion/increased yield were reported for tetracycline, chlortetracycline, oxytetracycline, whilst for doxycycline no suitable data for the assessment were available. Uncertainties and data gaps associated with the levels reported were addressed. It was recommended to perform further studies to supply more diverse and complete data related to the requirements for calculation of the FARSC for these antimicrobials.

Maximum levels of cross-contamination for 24 antimicrobial active substances in non-target feed. Part 9: Polymyxins: colistin

The specific concentrations of colistin in non-target feed for food-producing animals, below which there would not be an effect on the emergence of, and/or selection for, resistance in bacteria relevant for human and animal health, as well as the specific antimicrobial concentrations in feed which have an effect in terms of growth promotion/increased yield were assessed by EFSA in collaboration with EMA. Details of the methodology used for this assessment, associated data gaps and uncertainties, are presented in a separate document. To address antimicrobial resistance, the Feed Antimicrobial Resistance Selection Concentration (FARSC) model developed specifically for the assessment was applied. However, due to the lack of data on the parameters required to calculate the FARSC, it was not possible to conclude the assessment until further experimental data become available. To address growth promotion, data from scientific publications obtained from an extensive literature review were used. Levels of colistin in feed that showed to have an effect on growth promotion/increased yield were reported. It was recommended to carry out studies to generate the data that are required to fill the gaps which prevented the calculation of the FARSC for these antimicrobials.

Maximum levels of cross-contamination for 24 antimicrobial active substances in non-target feed. Part 6: Macrolides: tilmicosin, tylosin and tylvalosin

The specific concentrations of tilmicosin, tylosin and tylvalosin in non-target feed for food-producing animals, below which there would not be an effect on the emergence of, and/or selection for, resistance in bacteria relevant for human and animal health, as well as the specific antimicrobial concentrations in feed which have an effect in terms of growth promotion/increased yield, were assessed by EFSA in collaboration with EMA. Details of the methodology used for this assessment, associated data gaps and uncertainties, are presented in a separate document. To address antimicrobial resistance, the Feed Antimicrobial Resistance Selection Concentration (FARSC) model developed specifically for the assessment was applied. However, due to the lack of data on the parameters required to calculate the FARSC, it was not possible to conclude the assessment until further experimental data become available. To address growth promotion, data from scientific publications obtained from an extensive literature review were used. Levels in feed that showed to have an effect on growth promotion/increased yield were reported for tilmicosin and tylosin, whilst for tylvalosin no suitable data for the assessment were available. It was recommended to carry out studies to generate the data that are required to fill the gaps which prevented the calculation of the FARSC for these three antimicrobials.

Aspergillus awamori positively impacts the growth performance, nutrient digestibility, antioxidative activity and immune responses of growing rabbits

In this study, we explored the effects of dietary administration of Aspergillus awamori on the growth, intestinal histomorphology, immune parameters and antioxidant enzyme activity of growing rabbits. The rabbits of 5 weeks of age (body weight, 855 ± 5.53 g) were allotted into four groups (12 rabbits per group) and fed four experimental diets enriched with A. awamori at 0, 50, 100 and 150 mg per kg diet for 8 weeks. After the feeding trial, an equal number of male APRI rabbits (3 months old; 4 groups, 5 rabbits per group) were housed in metabolism cages and fed the test diets for 14 days for the digestibility trial. All A. awamori-enriched diets induced a significant increase in the average body weight and weight gain of rabbits and significantly decreased the feed conversion ratio. In rabbits fed with A. awamori at 100 or 150 mg per kg diet, protein, lipid and fibber digestibility coefficients significantly increased compared with the control group. Intestinal villi measurements (length and thickness) were also enhanced in all rabbits fed with A. awamori. Adding A. awamori as a food supplement generally did not affect rabbit haematology and blood biochemistry values; however, at 150 mg per kg diet, it significantly increased the levels of haemoglobin and total protein, as well as red blood cell count. Furthermore, all enriched diets significantly increased rabbits' phagocytic activity and their phagocytic index. Rabbits fed with A. awamori also showed decreased malondialdehyde but increased catalase activity. In conclusion, A. awamori administered as feed supplement at 100-150 mg per kg of growing rabbits' diet enhances their growth, intestinal health and nutrient digestibility, and it raises the levels of their immune and antioxidative responses.

Dietary Mannan-oligosaccharides potentiate the beneficial effects of Bifidobacterium bifidum in broiler chicken

This study investigated the effects of dietary Bifidobacterium bifidum (BFD) and mannan-oligosaccharide (MOS), as a synbiotic, on the production performance, gut microbiology, serum biochemistry, antioxidant profile and health indices of broiler chicken. Six dietary treatments were T1 (negative control), T2 (positive control-20 mg antibiotic BMD kg^-1 diet; BMD: bacitracin methylene disalicylate), T3 (0·1% MOS + 10⁶  CFU BFD per g feed), T4 (0·1% MOS + 10⁷  CFU BFD per g feed), T5 (0·2% MOS + 10⁶  CFU BFD per g feed) and T6 (0·2% MOS + 10⁷  CFU BFD per g feed). Significantly (P < 0·01) better growth performance and efficiency was observed in birds supplemented with 0·2% MOS along with 10⁶  CFU BFD per g of feed compared to BMD and control birds. Supplementation with 0·2% MOS along with either 10⁶ or 10⁷  CFU BFD per g feed reduced (P < 0·01) the gut coliform, Escherichia coli, total plate count, and Clostridium perfringens count and increased the Lactobacillus and Bifidobacterium count. Significantly (P < 0·01) higher serum and liver antioxidant enzyme pool, serum HDL cholesterol and lower serum glucose, triglyceride, total cholesterol, cardiac risk ratio, atherogenic coefficient and atherogenic index of plasma were observed in birds supplemented with 0·2% MOS along with 10⁶  CFU BFD per g of feed compared to control or BMD supplemented birds. Better production performance, gut microbial composition, serum biochemistry, antioxidant profile and health indices were depicted by broiler chicken supplemented with 0·2% MOS and 10⁶  CFU BFD per g of feed.

Growth, immunity, relative gene expression, carcass traits and economic efficiency of two rabbit breeds fed prebiotic supplemented diets

The current study designed to evaluate the effect of oligosaccharide supplemented diets on growth performance, histomorphometric changes, economic efficiency and genetic expression of some growth and immunity-relative genes. One hundred and twenty weaned male rabbits, six weeks of age of two breeds (NZW and APPRI) were randomly allocated into six equal groups; the first supplemented with 0.3% Mannan-oligosaccharide (MOS), the second supplemented with 0.05% Isomalto-oligosaccharide (IMO) and the third considered a control group. Each group contained ten equal replicates. The highest Final body weight and feed consumption were recorded in MOS and IMO groups compared with control. Fortified feed diet with IMO significantly increased duodenal villi area and length than MOS and control groups. At the same time, Spleen white bulb area and length were significantly higher in MOS and IMO than control. Supplementation of MOS and IMO significantly improved carcass traits, economic efficiency and induced certain modifications in some major key genes involved in the regulation of nutrients metabolism, immunity and growth in different tissues. In conclusion, dietary supplementation of MOS and IMO had a desirable positive impact on productive and economic efficiency in the rabbit.

Early Introduction of Solid Feeds: Ingestion Level Matters More Than Prebiotic Supplementation for Shaping Gut Microbiota

Early introduction of a nutritional substrate is a promising biomimetic strategy for controlling the implantation of the microbiota and preserving the health of young animals. In this study, we provided experimental solid substrate in a gel form to stimulate suckling rabbits' intake and to investigate its effects on microbiota implantation and colonization. All the rabbits had access to solid feed outside the nest as of 15 days of age. Except for the control group, rabbits were offered starter feed gels inside the nests from 3 to 18 days of age. These gels were either free of additives (AF_GEL) or contained 4% of fructo-oligosaccharides (FOS_GEL) or 4% of mannan-oligosaccharides and β-glucans mixtures (MOS_GEL). The cecal content of 160 rabbits was sampled at 18, 29, 38, and 57 days of age and analyzed using 16S rRNA gene sequencing. Pups consumed an average of 3.95 ± 1.07 g of starter feed gel with a higher intake when it was supplemented with fructo-oligosaccharides (+1.2 g; P < 0.05). Starter feed gel consumption increased the ensuing intake of pellets (+17 g from 15 to 21 days; P < 0.05). Alpha-diversity indexes were similar between groups and prebiotic supplementation did not induce a clear shift in microbiota pattern. Conversely, when considering rabbits that consumed more starter feed, the highest proportions of bacteria with plant-degrading abilities, such as species from the Lachnospiraceae and Ruminococcaceae families, were observed at 18 days of age. However, fermentative activities were not affected by starter feed intake at 29, 38, and 57 days of age. By providing comprehensive results on the regulation of microbial community structure at the onset of solid feed intake, this research paves the way for further studies on digestive ecosystem maturation.

Evaluation of the carryover effect of antibiotic, bee pollen and propolis on growth performance, carcass traits and splenic and hepatic histology of growing rabbits

Sixty-four nulliparous female rabbits were distributed among eight groups (eight animals/group). Group one was the unsupplemented control group; the other seven groups were supplemented with zinc bacitracin (ZnB) at 100 mg, or bee pollen (BP) and/or propolis (Pro) at 150 and 300 mg in a capsulated form, three times a week, day after day, continuously all over the experimental period. The experiment was run for eight parties; at each parity, 28 kids of each doe group (a total of 224 rabbits) were divided into two subgroups weaned, respectively, at 24 and 30 days of age. Thus, for each parity, there were 16 groups (eight does treatments × two weaning age, 14 rabbits per group). The growing rabbits fed the standard diets without supplements. The growth performance, the carcass traits, the liver and the spleen histology of rabbits were checked up to 90 days of age to find possible carryover effects of the supplements. The supplements had no significant effect on most of the growth performance at 90 days of age, but BP150 and BP+Pro300 increased the growth rate in comparison with ZnB group. The liver weight in the control, BP300 and Pro300 groups was higher than the ZnB one. The spleen weight was higher in the groups ZnB, BP150, Pro300 and BP+Pro300, followed by the control, BP300 and BP+Pro150 and thus Pro150. The heart % in the BP150 and Pro300 groups was higher than ZnB and BP+Pro150 groups. A lymphoid hyperplasia of splenic white pulp was observed in the BP+Pro groups, while propolis alone showed a mild activation of lymphobiosis. The Pro and BP groups showed the same picture of the control group exhibiting a hydropic degeneration of mostly hepatic cells, while the ZnB group exhibited adverse effect on the bile ducts featuring portal periductal inflammatory cells infiltration with epithelial hyperplasia reflecting chronic cholangitis.

Bee pollen and propolis as dietary supplements for rabbit: Effect on reproductive performance of does and on immunological response of does and their offspring

To evaluate the effect of bee pollen (BP) and/or propolis (Pro) supplementation on rabbit does, 64 nulliparous NZW rabbits does were distributed among eight groups (eight animals/group). One unsupplemented group was the control; the other seven groups were supplemented, respectively, with zinc bacitracin (ZnB) at 100 mg, BP at 150 and 300 mg, Pro at 150 and 300 mg, BP+Pro at 150 and 300 mg of each three times/week, day after day continuously along eight parities. The BP300, Pro300 and BP+Pro150 groups had higher body weight of litter at birth and number of kids born alive. The BP supplementation at 150 mg increased plasma total protein and albumin than the control group. The BP or Pro at 150 mg decreased plasma T₃ than the other groups except for BP+Pro150. The ZnB group had significantly greater T₃ /T₄ ratio compared to BP, Pro and BP+Pro at 150 mg. The BP+Pro150 group had less ALT than the control; BP300 and Pro 300 mg resulted in lower plasma AST than the groups Pro150 with or without BP and the control group. The plasma alkaline phosphatase of BP at 150 or 300 mg and BP+Pro150 was significantly greater than that of the Pro150 group. The BP+Pro300 group had higher WBCs than the other groups. In contrast, the lymphocytes were greater in the Pro and BP+Pro300 groups than in BP, Pro and BP+Pro at 150 mg. The groups supplemented with BP and BP+Pro at 150 and 300 mg had significantly greater SRBCs of doe rabbits and their offspring compared to the control and the ZnB group. The BP at 300 mg increased the serum albumin and α₁ -globulin than the control group. The Pro300 group had greater serum α₂ -globulin and β-globulin than the control group. The total globulin was significantly greater for the 300 mg propolis-supplemented groups than the control.

Organic Selenium, Probiotics, and Prebiotics Effects on Growth, Blood Biochemistry, and Carcass Traits of Growing Rabbits During Summer and Winter Seasons

The effect of organic selenium, prebiotics, or probiotics on productive performances, blood biochemistry, and carcass characteristics of growing rabbits was studied throughout summer and winter seasons. In an 8-week feeding trial, a total of 100 New Zealand White rabbits were randomly distributed to 10 groups. Two seasons (winter and summer) and five diets fortified with 0 (control), 0.03 mg selenium, 3 g Bio-Mos®, 1 g Bactocell® (1 × 10¹⁰ CFU) or 3 g yeast/kg diet were used in 2 × 5 factorial design. Results indicated that growth performance, feed intake (FI), and blood components (red blood cells [RBCs], serum total protein [TP], globulin [GLOB], albumin [ALB]) decreased significantly in rabbits reared during summer than in those during winter. In contrast, white blood cells, urea-N, creatinine, alanine transaminase [ALT], and aspartate transaminase [AST] increased significantly in summer. However, growth performance indices, FI, blood hemoglobin, RBCs, TP, ALB, and GLOB increased significantly in rabbits when fed the tested feed additives. The respiration rate, rectal temperature, and heart rate of the animals were significantly decreased with all feed additives. Adjusted weight of carcass, liver, kidney fat, and carcass cuts were not affected by feed additives. Final margin and margin efficiency increased in rabbit fed diets supplemented with feed additives than those fed the basal diet without any supplementation. Results of the current study concluded that a supplementation of rabbit diets with organic selenium, probiotics, and prebiotics can promote rabbit performance during mild weather and also alleviate the adverse impact of heat stress during summer season.

Blood Hematological and Biochemical Constituents, Antioxidant Enzymes, Immunity and Lymphoid Organs of Broiler Chicks Supplemented with Propolis, Bee Pollen and Mannan Oligosaccharides Continuously or Intermittently

This study investigate the effect of bee pollen (BP) and/or propolis (Pro) as an alternative to Mannan oligosaccharides (Bio-MOS, a hydrolyzed yeast with natural and artificial flavors Alltech Inc) when given continuously or intermittently on antioxidant enzymes, immunity, weight and morphology of lymphoid organs of broilers. Thus, 324 unsexed one-day-old Arbor Acres broilers were randomly distributed into nine treatment groups, each replicated 6 times of 6 birds per replicate. The chicks were kept in wire cages and fed the same basal diet and were submitted to the following treatments: control without supplementation (control) or supplemented with BP at 300 mg, Pro at 300 mg, BP+Pro at 300 mg each and Bio-MOS at 0.5 g/kg diet. Each supplemented group was subdivided into two subgroups in which the additives were supplied continuously or intermittently. In the continuously supplemented groups, supplementations were given from one till 36 days of age, and in the intermittently supplemented groups, the administration was only three days before, on the day of and day after vaccination. The BP and Pro supplied continuously or intermittently was equally potent for improving immunity, antioxidant enzymes similar to Bio-MOS. All supplements supplied either continuously or intermittently resulted a significantly higher thymus (P < .04) and bursa weights (P < .001) than the control group. Combining BP with Pro resulted in a further increase in thymus weights and small follicle diameter compared to the control group. In addition, thymus percentage in the group received BP+Pro showed a further increase compared to the control and Pro supplemented intermittently. Bio-MOS, when supplied continuously or intermittently, resulted in the greatest response in splenic lymphoblasts. Supplementation with either BP or Pro intermittently, is adequate to promote health and immune response of broiler chicks, with 40% saving of supplementation costs.

Pyrosequencing study of caecal bacterial community of rabbit does and kits from a farm affected by epizootic rabbit enteropathy

<p>Epizootic Rabbit Enteropathy (ERE) is a disease of unknown aetiology that mainly affects post-weaning animals. Caecotrophs from animals in a farm affected by ERE were analysed to identify changes in the microbiological profile of growing rabbits. Does and kits at weaning (28 d) and the same rabbits ten days later (38 d) were used for a comparison using Roche 454 pyrosequencing of hypervariable V3-V5 regions of the 16S <em>rRNA</em> genes. The caecal bacterial community was dominated by the Firmicutes phylum (about 80%), followed by Bacteroidetes (15%), although relative abundances changed according to animal age (among does and kits at 28 and 38 d) and health status (affected or not by ERE). Two dominant families were classified within the Firmicutes phylum: Ruminococcaceae and Lachnospiraceae (50 and 20% of the sequences, respectively). In kits affected by ERE, relative abundance of <em>Ruminococcus</em> and <em>Bacteroides</em> genera decreased and increased, respectively, compared to healthy kits at the same age (28 and 38 d). The principal coordinate analysis plot revealed that kits at 28 d of age cluster together and apart from the does and the healthy 38-d rabbit groups. When only growing rabbits are considered, kits that showed symptoms of ERE clustered separately. Results suggest a different caecal bacterial community of rabbits affected by ERE. These findings highlight the need to identify different stages of the disease.</p>

Effect of diet supplementation with live yeast Saccharomyces cerevisiae on growth performance, caecal ecosystem and health of growing rabbits

<p>The aim of this study was to determine the effect of the live yeast Saccharomyces cerevisiae on the growth performance, caecal ecosystem and overall health of growing rabbits. A control diet was formulated (crude protein: 15.9%; neutral detergent fibre: 31.6%) and another diet obtained by supplementing the control diet with 1 g of Saccharomyces cerevisiae (6.5×109 colony-forming units) per kg of diet. Ninety 35-d old rabbits were allotted into 3 groups: TT (rabbits offered the supplemented diet from 17 d of age onwards), CT (rabbits offered supplemented diet from 35 d) and CC (rabbits fed non-supplemented diet). Body weight (BW) and feed intake were measured weekly and mortality was controlled daily. At 35, 42 and 77 d of age, 6 rabbits from each group were slaughtered and digestive physiological traits, serum clinical chemistry parameters, fermentation traits, and the composition of caecal microbiota examined. At 42 and 56 d of age, 10 rabbits from each group were injected intraperitoneally with 100 μg/animal of ovalbumin and blood samples were collected for examination of plasma immunological parameters. Throughout the experiment (5-11 wk), weight gain and feed intake (37.8 and 112.6 g/d, on av.) were not affected by yeast, except for weight gain in the first week after weaning, which was the highest in TT animals among the 3 groups (48.1 vs. 43.9 and 44.2 g/d for TT, CC and CT, respectively; P=0.012). This may be due to the increased trend in feed intake (P=0.072) in the TT group (96.4 g/d) compared to the others. Mortality (5/90) was low and did not differ among the 3 groups. Treatments had no effect on slaughter traits at the 3 sampling dates (35, 42 and 77 d). Only the weight of the empty caecum (% BW) was higher (P=0.02) in CC (2.2%) and CT (2.3%) than in TT group (1.8%) at 77 d of age. Treatments did not overtly affect the caecal microbiota, although the number of total anaerobic bacteria and Bacteroides were lower (108 and 107/g caecal digesta, respectively) in rabbits from CC group compared to those of CT and TT groups at 42 d of age (P=0.03). No difference between groups was observed for caecal short chain fatty acids profile, blood traits, or IgG and cytokine profile. In conclusion, supplementation of feed with yeast did not modify growth traits and resulted in only a temporary increase in weight gain and a slightly altered caecal microbiota after weaning.</p>

Productive and reproductive performance of rabbits does as affected by bee pollen and/or propolis, inulin and/or mannan-oligosaccharides

<p>The aim of the paper was to compare the effect of prebiotics (inulin and/or mannan-oligosaccharides, MOS) and bee products (bee pollen and/or propolis) on productive and reproductive performance of rabbit does. Seventy nulliparous V-line female rabbits were distributed among 7 groups. The groups were fed the same diet and received no supplements (control group), natural molecules (bee pollen and/or propolis) at 200 mg/kg body weight (BW) or prebiotics (inulin and/or MOS) at 35 mg/kg BW. Productive, reproductive, biochemical and haematological traits were investigated. Bee pollen with propolis significantly increased body weight gain of does 1 wk after mating (3.53%), decreased feed intake (4.49%) and caused larger litter size (39.4%), heavier body weight of litter (17.7%), a greater number of kits born alive (48.7%), higher weight of kits (87.81%) at 28 d of age, higher milk yield (43.6%) and more favourable milk conversion ratio (31.6%). Moreover, bee pollen with propolis had significantly increased plasma total protein (43.1%), albumin (45.7%), globulin (41.0) and progesterone (60.5%), and had a significantly decreased plasma cholesterol (31.1%), aspartate aminotransferase/alanine aminotransferase ratio (20.3%) compared to the control group. Does treated with growth promoters had significantly fewer services per conception (22%) and greater fertility rate (21%) compared to the control group. Inulin with or without MOS significantly increased plasma glucose (49.9 and 50%, respectively) and feed cost (90.2%) compared to the control group. Supplementation of MOS or bee pollen with or without propolis had significantly greater relative economic efficiency (61.9, 55.1 and 27.1%, respectively) than the control group. MOS and bee pollen with or without propolis are able to improve productive and reproductive performance and economic efficiency of rabbit does in comparison to the unsupplemented group.</p>

Effect of inulin and mannan-oligosaccharides compared with zinc-bacitracin on growing performance, nutrient digestibility and hematological profiles of growing rabbits

The study aimed to evaluate the effect of inulin and mannan-oligosaccharides (MOS) vs zinc-bacitracin (ZnB) on rabbit growth performance, nutrient digestibility, and blood profiles. In total, 108 rabbits 32 days of age were divided into four homogeneous groups fed the same basal diet and submitted to the following dietary treatments: control group, without supplementation; inulin group, supplemented with inulin (0.25 g/rabbit.day); MOS group, supplemented with MOS (0.083 g/rabbit.day); and ZnB group, supplemented with ZnB (0.083 g/rabbit.day). The supplements were administered 2 days per week from 32 to 81 days of age. At 32, 56 and 81 days, the rabbits were weighed and feed intake was measured. Mortality was recorded daily. Nutrient digestibility was measured at 65 days by an ingesta–excreta balance. Samples of blood were collected at 53, 67 and 81 days of age. The control group showed the highest (P < 0.01) mortality rate throughout the trial (17.0%), followed by ZnB (8.18%), inulin (3.7%) and then the MOS group, which had the lowest mortality (1.6%; P < 0.01). Addition of MOS led to a more favourable (P < 0.05) feed conversion ratio than addition of ZnB at 32–56 days of age and inulin for the entire trial period. The MOS group showed increased (P < 0.01) digestibility of dry matter, organic matter, ash and crude fibre relative to the control group. All supplements increased (P < 0.01) protein digestibility relative to the control. The level of alanine aminotransferase was reduced due to the use of feed supplements, and MOS supplementation gave the lowest (P < 0.01) value. Administration of prebiotics to growing rabbits as an alternative to ZnB can lead some advantages compared with both antibiotic and unsupplemented diets; MOS was more effective than inulin.