Growth performance, plasma metabolites, meat quality, and meat and lipid health indices of New Zealand White rabbits as affected by dietary dried tomato pomace powder supplementation during the summer season.

One hundred and twenty New Zealand White rabbits (NZW) (5-week-old; 735.27 ± 27.23 g) were kept in an open-sided house during the summer season. The experiment aims to evaluate the impacts of dried tomato pomace powder (DTPP) supplementation on rabbits' performance, blood metabolites, carcass traits, meat quality, and lipid and health indices of NZW rabbits during 5-13 weeks of age. The four treatments were a standard rabbit feed (control) and the control diet supplemented with 0.5, 1.0, and 1.5% DTPP, respectively. Rabbits fed a diet containing 1.5% DTPP showed the highest growth rate through weeks 9-13 of age despite having the lowest feed intake spanning 5-13 weeks. The best feed conversion ratio (FCR) was recorded in rabbits fed with 1.5% DTPP-supplemented diet for 5-13 weeks. Diets supplemented with 0.5 or 1.0% DTPP enhanced markedly dressing %, total edible flesh, saturated (SFAs), monounsaturated (MUFAs), and polyunsaturated fatty acid (PUFAs) contents, as well as the ∑n - 6/∑n - 3 ratio and the total n - 6 of meat. Dietary supplementation with DTPP decreased kidney, abdominal, and back fat. Diets supplemented with DTTP decreased total cholesterol, triglycerides, and very low-density lipoprotein (vLDL) concentrations. The greatest levels of linoleic acid, arachidonic and water-holding capacity in meat were observed in rabbits fed 1.5% DTPP-supplemented diets. Diets containing 1 and 1.5% DTPP improved meats' atherogenic and thrombogenic indices, meat lipid quality desired fatty acids/undesired fatty acids ratio, and meat health index. Conclusively, DTPP up to 1.5% maintained the growth performance of rabbits, boosted meat quality through increasing vitamin E, reduced fat deposition, modified fatty acid composition, and improved atherogenic, thrombogenic, and hypocholesterolemic indices of rabbit meat.

Association of single nucleotide polymorphisms in Neuropeptide Y (NPY) and Phosphoglycerate Mutase 2 (PGAM2) genes with growth traits in rabbits.

Genetic improvement of local rabbit breeds using modern approaches such as marker-assisted selection requires accurate and precise information about marker‒trait associations in animals with different genetic backgrounds. Therefore, this study was designed to estimate the association between two mutations located in the Neuropeptide Y (NPY, g.1778G > C) and Phosphoglycerate Mutase 2 (PGAM2, c.195 C > T) genes in New Zealand White (NZW), Baladi (BR), and V-line rabbits. The first mutation was genotyped using high-resolution melting, and the second mutation was genotyped using the PCR-RFLP method. The results revealed significant associations between the NPY mutation and body weight at 10 (V-line) and 12 weeks of age (NZW, BR, and V-line), body weight gain (BWG) from 10 to 12 weeks of age (BR), BWG from 6 to 12 weeks of age (NZW, BR, and V-line), average daily gain (NZW, BR, and V-line, and BR), growth rate (GR) from 8 to10 weeks (V-line), 10 to 12 weeks (BR), and GR from 6 to 12 weeks of age (BR, and V-line). The PGAM2 mutation was associated with body weight at 10 (V-line) and 12 (NZW, and V-line) weeks of age, with significant positive additive effects at 12 weeks of age in all breeds, and was associated with BWG from 8 to 10 and 10 to 12 in BR, and BWG from 6 to 12 weeks of age (NZW, and BR), and average daily gain (NZW, and BR), and was associated with GR form 8 to 10 weeks (BR), from10 to 12 weeks (BR, and V-line) and from 6 to 12 weeks (BR). The results highlighted the importance of the two mutations in growth development, and the possibility of considering them as candidate genes for late growth in rabbits.

Effect of fermented Cassava sievate and tiger nut shaft on growth performance, blood profile and immunological parameters in male rabbits.

This study examined the effects of using mushroom mycelium to ferment tigernut and cassava pulp on the growth performance, haematology and immunology of rabbits. Seventy-five New Zealand Bulk grower rabbits were randomly distributed to four treatment groups and a control group in a completely randomized approach. The treatment groups were fed with formulated experimental diets containing one of fermented tigernut drink by-product (FT), fermented cassava sievate (FC), unfermented tigernut drink by-product (UT), or unfermented cassava sievate (UC). The control group was fed a basal diet with no additives. The proximate composition of the fermented feed was analyzed. The weight gain of the animals was, 834.5, 633, 790, 510, and 706 g for control, FT, FC, UT, and UC respectively. The packed cell volume (PCV) for animals in the control group, FT, and FC are 34.33, 37.26, and 32.29% respectively. The red blood cell (RBC) of the FT was favourably improved (5.53 × 1012/L) compared to those of UT (2.28 × 1012/L), while there was a reduction in the red blood cell count of FC group (1.02 × 1012/L). Conclusively, the inclusion of fermented tiger nut drink by-product in rabbit feed improved the PCV and RBC of the rabbits' understudy but did not affect their growth performance.

Influence of multi-enzyme preparation supplemented with sodium butyrate on growth performance blood profiles and economic benefit of growing rabbits.

The present study was carried out to explore the impacts of dietary supplementation of enzyme mixture with sodium butyrate on the growth performance, carcass traits, blood profile and economic benefit in two breeds of weanling rabbits adapted to survive in Egypt (New Zealand White and Rex). One-hundred and twenty weaned male rabbits (New Zealand White and Rex) of 6 weeks of age and 770.5 ± 20 g body weight were allotted randomly into four groups in a factorial arrangement. The obtained results indicated that there were non-significant differences in all growth performance traits, blood profile and economic parameters due to the breed effect. However, there were significant differences in most of carcass traits due to the breed effect except total giblets and New Zealand White breed showed the highest value of these parameters including dressing % (p < .01), forequarter and loin % (p < .001) and hindquarter % (p < .003) compared with Rex breed counterparts. The effect of the treatment and its interaction with the breed significantly (p < .05) improved body weight gain, feed consumption and carcass traits (percentage of dressing, forequarter, hind quarter and lion). However, final body weight and feed conversion ratio were not significantly influenced. Supplementing a diet with treatment significantly decreased blood triglycerides, cholesterol and the ratio between albumin and globulin (A/G ratio), while increased blood total protein and globulin. Although higher feed cost and total costs in treated groups than control ones in each breed, they showed higher total return and net return. Rex non-treated rabbit breed showed the lowest profitability measures compared with other groups. In conclusion, dietary supplementation of multi-enzyme with sodium butyrate is highly recommended in growing rabbits due to their beneficial effects on the growth performance and profitability.

Dietary supplementation of potassium sorbate, hydrated sodium calcium almuniosilicate and methionine enhances growth, antioxidant status and immunity in growing rabbits exposed to aflatoxin B1 in the diet.

The present experiment was conducted to evaluate the effect of dietary supplementation with some feed additives (potassium sorbate; Sor, hydrated sodium calcium almuniosilicate; Hsc and L-methionine; L-M) against aflatoxin B1 (AF) toxicity in rabbits. A total of 72 growing rabbits (5-week-old) were distributed into six equal groups (4 replicates with 3 rabbits each). The experimental groups are as follows: control group, AF group (supplemented with AF 0.3 mg/kg diet), AF + Sor group (AF 0.3 mg/kg diet + Sor 2 g/kg diet), AF + Hsc group (AF 0.3 mg/kg diet + Hsc 5 g/kg diet), AF + L-M group (AF 0.3 mg/kg diet + L-M 8 g/kg diet) and AF + Mix group (AF 0.3 mg/kg diet + 2 Sor + 5 Hsc + 8 L-M g/kg diet). Live body weight and weight gain at 13 weeks of age were significantly reduced by AF. Feed intake at 13 weeks of age was decreased in AF, AF + Hsc and AF + Mix compared to the control. AF, AF + Hsc and AF + Mix showed the lowest total antioxidant capacity compared to the control. The highest level of reactive oxygen species and 8-Hydroxy-2-desoxyguanosine was observed in AF group. Using of other supplements with AF increased immunoglobulinM than AF alone. In conclusion, dietary supplementation of Sor, L-M, Hsc or their mixture was effective in reducing the adverse effects of AF on performance, antioxidant and immune status of rabbits with more better improvement obtained by Sor or L-M separately.

Methionine promotes the development of hair follicles via the Wnt/ß-catenin signalling pathway in Rex rabbits.

To investigate the effect and molecular mechanism of methionine (Met) on the growth of hair follicles (HFs) in Rex rabbits. A total of 200 weaning Rex rabbits were divided into four groups and fed varying levels of Met-supplemented diets. We measured the HF density on dorsal skin and the Wnt/ß-catenin pathway protein expression level. Meanwhile, whole HFs were isolated from Rex rabbit skins and cultured with Met in vitro to measure hair shaft growth. The relationship between Met and the Wnt/ß-catenin signalling pathway was also characterized by using the Wnt/ß-catenin signalling inhibitor, XAV-939. The results showed that the addition of dietary Met could significantly increase the HF density on dorsal skin (p < .05) and enhance the protein expression level of Wnt10b (p < .05), ß-catenin (p < .05) and DSH (p < .05). Methionine stimulation could also prolong the hair shafts growth in vitro (p < .05). And inhibition of Wnt/ß-catenin signalling using XAV-939 could eliminate this phenomenon. In summary, Met can increase the density of HFs on dorsal skin in vitro and prolong the hair shaft growth of HFs in vivo via the Wnt/ß-catenin signalling pathway.

Productive performance, lipid profile and caecum microbial counts of growing rabbits treated with humic acid.

The aim of the present study was to evaluate the effect of a humic acid (HA)-supplemented diet on productive performance and some physiological parameters of growing rabbits. A total of 80 weaned V-line rabbits at an age of 4 weeks were randomly divided into four groups. Rabbits of groups 2, 3 and 4 were fed diet containing 35 (HA35), 70 (HA70) and 105 (HA105) mg Humic acid/kg diet while the first group served as control (HA0). Body weight gain was positively affected by HA treatment. HA105 rabbits had the improved feed conversion value. HA treatments had significantly reduced plasma cholesterol concentration and significant increased red blood cells, white blood cells count and plasma high-density lipoprotein concentrations. However, serum aspartate amino transferase and alanine amino transferase activities, creatinine and the apparent nutrients digestibility values were not affected by HA treatments. Organic matter digestibility of all HA-treated groups significantly increased compared with HA0. At 63 days of age (after 35 days of treatment), caecum microbial counts decreased (total bacteria and Escherichia coli) with HA treatments. Generally HA could be considered as a biological as growth promoter feed additive alternative to antibiotics.

Effect of dietary pomegranate by-product extract supplementation on growth performance, digestibility, and antioxidant status of growing rabbit.

The study objective was to investigate the effect of three levels of dietary pomegranate by-product extract (PBE) (100, 150, and 200 mg) on growth performance, nutrient digestibility, carcass characteristics, and some blood parameters. Sixty weaned New Zealand White (NZW) rabbits at 5 weeks of age with an average body weight 561.67 ± 6.68 g were randomly allotted to four dietary groups; each group included three replicates (five rabbits each). The control group was fed a basal diet without PBE; the other three experimental groups fed diets supplemented with PBE at 100-, 150-, and 200-mg/kg diet. The results revealed that dietary supplementation of PBE at each level significantly (P < 0.05) improved the average final body weight and FCR. Rabbits group fed diet supplemented with 200 PBE recorded the highest (P < 0.05) of all nutrients digestibility, DCP, TDN, and DE. Feeding rabbits on diets supplemented with PBE at levels 100-, 150-, and 200-mg/kg diet increased (P < 0.05) plasma concentrations total protein, albumin, globulin, HDL, TAC, SOD, and GSH-Px, compared to the control group. The opposite trend was noticed with glucose, total lipids, triglycerides, total cholesterol, and LDL concentrations whereas they were lower (P < 0.05) than those of the control group. The obtained results also showed that PBE supplementation levels reduced (P < 0.05) both E. coli and salmonella counts in rabbit cecum. It could be concluded that the supplementation of rabbit diets with PBE at 100-, 150-, and 200-mg/kg diet improved growth performance and the nutrient digestibility. Moreover, PBE had an antioxidant and antibacterial effect of the growing rabbits.

Growth performance, biochemical, cytological and molecular aspects of rabbits exposed to lead toxicity.

Heavy metals have enormous variety of deleterious effects on many organs in the body. This study demonstrated the toxic influences of lead on the growth, biochemical, cellular and molecular aspects of developing rabbits. Seventy-five rabbits (New Zealand NZW) were divided into five equal groups as follows; control (C) and four treatment groups (T1-4) orally administered lead acetate solution as follow T1: 20, T2: 30, T3: 50 and T4: 70 mg/kg body weight. Lead resulted in a significant decrease in live body weight, daily body weight gain and feed intake in T3 and T4 compared to those in other groups. Blood haematology measurements such as red blood cells, haematocrit (HCT), mean corpuscular volume, platelet, white blood cells and lymphocytes were significantly influenced by the high level of lead. Oral administration of lead significantly reduced total proteins in the serum. It was observed that the high lead level led to significantly (p < 0.05) increased levels of aspartate aminotransferase, alanine aminotransferase enzymes, urea and creatinine. Four random amplified polymorphic DNA primers polymorphism were detected among the treatment groups. Total number of induced bands (loss or appearance) compared with control group were 4, 10, 10 and 14 bands using primers P1, P2, P3 and P4 respectively. Number of micronuclei showed a dose-response increase and the difference was highly significant especially between control compared with T3 and T4 groups. From our results, we can conclude that exposure of rabbits to lead acetate resulted in negative effects on the growth performance and altered the haematological and biochemical parameters, in addition to its adverse impact on cytological and molecular characterization of animals.

Responses of growing rabbits to supplementing diet with a mixture of black and red pepper oils as a natural growth promoter.

The current study was explored to examine the impacts of dietary inclusion of mixture of black (BPO) and red pepper (RPO) oils as growth promoters on growth, carcass, blood haematology, serum chemistry, immunity and antioxidative status of New Zealand White rabbits (NZW). A number total of 100 5-week-old NZW growing weaned rabbits were randomly allocated into four treatment groups in a complete randomized experiment. The dietary treatment groups were as follows: control: basal diet; BRP0.5: basal diet + 0.25 g BPO + 0.25 g RPO/kg diet; BRP1.0: basal diet + 0.50 g BPO + 0.50 g RPO/kg diet; and BRP1.5: basal diet + 0.75 g BPO + 0.75 g RPO/kg diet. Rabbits fed the highest level of BRP mixture were the heaviest, while the control rabbits were the lightest. During 5-9 weeks of age, a gradual improvement in feed conversion ratio (FCR) was noticed with increasing BRP level. The control group excelled all BRP groups regarding the majority of blood haematological parameters. Liver function was better in rabbits fed BRP enriched diets than the control. A gradual depression (p < 0.05 or 0.01) in serum lipids regardless high-density lipoprotein (HDL) were recorded with elevating BRP level in the diet. The supplementation of BRP mixture enhanced the immune function and serum superoxide dismutase (SOD) activities and depressed serum malondialdehyde (MDA) in comparison with control. It could be concluded that dietary BRP mixture can affect some of growth traits, improve the immunity and antioxidant parameters, lower lipid profile and lipid peroxidation. Based on the study results, the recommended level of BRP mixture is 1.5 g/kg diet.

The effects of dietary tomato powder (Solanum lycopersicum L.) supplementation on the haematological, immunological, serum biochemical and antioxidant parameters of growing rabbits.

Using nutritional antioxidants in livestock systems is considered the key in improving animal production. The current study assumes that dietary tomato powder (TP) supplementation positively affects haemato-immunological, biochemical, and antioxidant parameters for New Zealand rabbits. A total of 30 rabbits (45 days old) were assigned to three groups, including a diet with no additives (control), and two dietary treatments with the providing of 1% or 2% TP. Mass spectrometric study for TP methanolic extract showed some phenolic compounds. Consumption of TP supplemented diets significantly (p < 0.001) affected body weight gain and feed efficiency. Red blood cells and white blood cells count exhibited a significant increase (p < 0.001) in both TP groups compared with the control. In addition to, feeding rabbits on TP enhanced cell-mediated and humoral immune responses through a significant increase in phagocytosis, chemotaxis, and levels of immunoglobulins (TIg, IgG, IgM and IgA). Supplementation of TP significantly (p < 0.01) reduced lipid profile induces except high-density lipoprotein cholesterol values. A remarkable significant (p < 0.001) effect on serum and hepatic oxidative stress responses were observed with TP addition. Ultimately, TP supplementation could play a potential role as a growth and health enhancer for fattening rabbits.

Effects of dietary sorghum dried distiller's grains with solubles on growth performance, diet nutrient digestibility, carcass characteristics and immunity in growing rabbits.

Sorghum dried distiller's grains with solubles (S-DDGS) are distillation extract residues from the ethanol fuel industry. In this experiment, two hundred 42-day-old rabbits were randomly allocated to five experimental diets containing 0 g/kg (control), 75, 150, 225 and 300 g/kg S-DDGS. The experiment lasted for 4 weeks. No difference was found in the average daily feed intake (ADFI; p > 0.05). With increasing sorghum inclusion, the average daily gain (ADG) was linearly (p < 0.001) and quadratically (p = 0.039) reduced, while, conversely, the feed conversion ratio (FCR) linearly (p < 0.001) increased. Increasing the amount of S-DDGS in the diet linearly decreased (p < 0.001) the apparent total tract digestibility (ATTD) of dry matter (DM), organic matter (OM), crude protein (CP) and ash. Carcass weight, carcass yield, heart and liver weights were linearly decreased by an increase in the amount of S-DDGS added to diets (p < 0.001), but no difference was observed between the 0, 75 and 150 g/kg S-DDGS groups (p > 0.05). Serum IL-6, IL-10 and SIgA linearly increased (p = 0.008) with increasing levels of S-DDGS in the diet. Rabbits fed 0, 75 and 150 g/kg of S-DDGS had similar IL-6 and IL-10 levels. Statistically significant differences in SIgA were observed between rabbits fed control diets and feed mixtures containing S-DDGS (p < 0.01). To conclude, S-DDGS can safely be added up to 75 g/kg, to the diet of rabbits. Increasing dietary S-DDGS inclusion may decrease the growth performance, nutrient digestibility and carcass traits, and activate immune responses.

Effect of dietary supplementation of recombinant Cry and Cp4 epsps proteins on haematological indices of growing rabbits.

Genetically modified (GM) crops expressing insect resistance and herbicide tolerance provide a novel approach for improved crop production but their advent at the same time presents serious challenges in terms of food safety. Although prevailing scientific proof has suggested that transgenic crops are analogous to their conventional counterparts, their use in human and animal diet gave rise to emotional public discussion. A number of studies had been conducted to evaluate the potential unintended effects of transgenic crops expressing single transgene, but very few studies for those with multiple transgenes. As the crops with single and multiple transgenes could impart different effects on non-target organisms, thus, risk evaluation of transgenic crops expressing more than one transgene is required to declare their biosafety. The present study was therefore designed to assess the effects of different levels of dietary transgenic cottonseed expressing recombinants proteins produced by Cry1Ac, Cry2A and Cp4epsps genes on haematological indices of growing rabbits. A total of 48 rabbits were assigned to four dietary treatments containing different levels of transgenic cottonseeds (i.e., 0% w/w, 20% w/w, 30% w/w and 40% w/w) with 0% w/w serving as control. Haematological parameters were measured at periodic intervals (0, 45, 90, 135 and 180) days. No significant (p > 0.05) dose-dependent effects were observed in most of the haematological parameters evaluated. Though, significant differences (p < 0.05) were recorded in the level of MCHC, MCH and HCT in some of experimental male and female rabbits, yet, they were not biologically significant, as all the differences were within the normal reference values. Our study suggested that feeding transgenic cottonseed of up to 40% could not adversely affect rabbit's haematological profile. However, further study needs to be conducted with different cotton genotypes expressing both single and polygenic traits before recommending the utilization of transgenic cottonseed in routine livestock feeding.

Effect of the ß-carotene oxygenase 2 genotype on the content of carotenoids, retinol and α-tocopherol in the liver, fat and milk of rabbit does, reproduction parameters and kitten growth.

Mutations in the ß-carotene oxygenase 2 (BCO2) gene can impair the function of the enzyme that breaks down carotenoids. As a result, gradual accumulation of unoxidized carotenoids in animal tissues gives them a yellow colour. The aim of the study was to determine the content of carotenoids, retinol and α-tocopherol in the liver, fat and milk of rabbit does with three different genotypes determined by AAT-deletion mutation at codon 248 of the BCO2 gene and to find out whether differences in the concentrations of the above compounds in the tissues and milk of the does affect reproduction parameters and the rearing rate of kittens. The experimental materials comprised 36 does, 12 of each genotype of the BCO2 gene, with their litters. Females with their litters were placed in individual cages, on deep litter. Between days 7 and 13 of lactation, samples of milk were collected from the does. The kittens stayed with their mothers until 35 days of age. After weaning, the does were sacrificed. Tissue samples of liver and perirenal fat were collected for chemical analyses. Additionally, based on samples taken from one female, RNA expression levels were determined from the mammary gland and liver, adipose tissue and skin. It was found that homozygous does with deletion at codon 248 of the BCO2 gene were characterized by considerably higher concentrations of xanthophylls and beta-carotene in the liver, adipose tissue and milk than does with the remaining genotypes. However, the differences in the content of the above compounds in milk had no influence on litter weight or the number and rearing rate of kittens. Additionally, RNA expression of the BCO2 gene was found in the mammary tissue of lactating doe and its level was similar to those noted in the liver and adipose tissue.

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.

Rabbit metabolic response and selected meat quality traits: Evaluation of dietary PLX® 23 and LycoBeads® feed supplement.

Effects of dietary supplementation of verbascoside and lycopene, alone and in combination, on some blood parameters, plasma oxidative status and meat quality traits in intensively reared rabbits were investigated. The test lasted 60 days and was conducted on 200 weaned-rabbits, divided into four groups of 50 animals each (5 animals each cage × 10 repetitions). The control group (CON) received a fattening feed without any feed supplements, whereas the experimental groups received the following: the first, an integration in 22 g of PLX® 23 (Lippia citriodora extract; VB group) per ton of feed; the second, an integration in 100 g of LycoBeads® (Solanum lycopersicum extract; LIC group) per ton of feed; and the third, an integration of both feed supplements in combination at the same doses (LIC+VB group). The dietary supplementation with Lippia citriodora and Solanum lycopersicum resulted in an improvement of the blood lipid profile, oxidative plasma markers, and hepatic and renal activity of treated growing rabbits. Feed additives also produced meat with a lower content in SFA and an increased PUFA content, and inhibited the lipid oxidation improving the oxidative stability of rabbit meat. The dietary supplementation, even reporting no effects on productive parameters and carcass yield, showed an improvement on several blood parameters, as indicator of animal welfare, and on quality and healthy meat markers.

Effect of bee pollen on growth performance, carcass traits, blood parameters, and the levels of metabolic hormones in New Zealand White and Rex rabbits.

The aim was to evaluate the effect of bee pollen (BP) on performance, blood parameters, and metabolic hormones in New Zealand White (NZW) and Rex (RX) rabbits. A total of 60 six-week-old rabbits were allotted into a completely randomized design in a 2 × 3 factorial arrangement (two breeds and three levels of BP: 0, 250, and 350 mg/kg body weight). The effects of breed × BP supplementation level were non-significant for all growth performance and carcass traits, as well as the concentrations of metabolic hormones in the plasma. Meanwhile, some blood parameters (hemoglobin, packed cell volume, alanine aminotransferase, aspartate aminotransferase, and urea) were significantly affected (P < 0.05). Regardless of the effect of breed, the supplementation of BP at a dose of 350 mg/kg BW increased the final body weight (P = 0.008), average daily gain (P < 0.001), and net profits (P = 0.006). However, the rabbits treated with BP at a dose of 250 mg/kg BW showed lower average daily feed intake (- 14.45 g/d; P = 0.049) and feed to gain ratio (- 0.48; P = 0.039). In both rabbit breeds, BP at a dose of 350 mg/kg increased the concentrations of insulin-like growth factor-1 (302.62 ng/ml, P < 0.001), insulin (16.63 ng/ml, P = 0.050), and triiodothyronine (158.50 ng/dl, P < 0.001) in plasma compared with other groups. It may be concluded that intake of BP supplementation can improve the feed to gain ratios, blood indices, and metabolic hormones in different rabbit breeds. However, the appropriate dosage and the route of supplementation of BP in broiler rabbits need further research.

Transcriptomic analysis reveals differentially expressed genes associated with wool length in rabbit.

Rabbit fur characteristics are primarily genetically determined traits. We used Illumina high-throughput sequencing technology to assess gene expression in the skin tissues of rabbits derived from a cross between Wanxi Angora rabbits and Rex rabbits, which exhibit differential characteristics of short and long wool respectively, to investigate molecular mechanisms related to wool length determination. To identify key regulatory genes involved in rabbit wool length, genes that were differentially expressed between the long- and short-wool rabbits based on a P-value < 0.05 and log2 |fold change| > 1 were characterized. A total of 798 genes were up-regulated and 523 were down-regulated in the long-wool group compared to expression levels in the short-wool group, and these genes were annotated with GO terms and KEGG pathways, revealing wool-development-related biological functions. The Wnt, Hedgehog and TGF-ß signaling pathways, which are related to cell proliferation, fibroblast proliferation and hair follicle regulation respectively, were identified. The expression levels of eight genes were validated by RT-qPCR. In addition, an interaction network was constructed to show the regulatory relationships among the differentially expressed genes. In this study, we found that FGF5, WNT5A, BMP4 and BMP7 showed significant differential expression between the two groups. These transcriptomic profiling results provide comprehensive gene expression information for improving understanding of the molecular mechanisms involved in the growth and development of rabbit wool.

Evaluation of haematological, serum biochemical and histopathological parameters of growing rabbits fed Amaranthus dubius.

Amaranthus dubius is an alternative source of fibre and protein for the feed formulation for growing rabbits, although its effects on their health status are yet unknown. Therefore, this study aimed to evaluate the effects of three dietary levels (0, 160 and 320 g/kg) of A. dubius on haematological, serum biochemical and histopathological parameters of fattening rabbits. One hundred and thirteen New Zealand White rabbits were fed ad libitum from weaning (35 days) to slaughter (87 days). The health status of the animals was monitored, and mortality was recorded. Before slaughtering, 30 rabbits were randomly selected for haematological and serum biochemical analysis. During slaughter, 18 rabbits were randomly selected for histopathological study in heart, liver, lung and small intestine. The health status of rabbits was good, with no differences among treatments in mortality. Diet and sex did not affect the values of most haematological and serum biochemical parameters. Fibrinogen, glucose and high-density lipoprotein values increased significantly from 0 to 320 g/kg A. dubius diets. The white blood cell count and glutamic oxaloacetic transaminase values decreased significantly from 0 to 320 g/kg A. dubius diets. The organs showed histologically well-structured tissues. However, in all experimental groups several samples with lesions were observed, always highly focalized in small tissue areas. The main lesions observed, probably related to conditions of thermal stress affecting the rabbits, were cholesterolosis (heart), steatosis (liver), inflammatory lymphoplasmacytic infiltrate (lung) and chronic inflammatory tissue damage (small intestine). In conclusion, the inclusion of up to 320 g/kg A. dubius in diet did not jeopardize the health status of growing rabbits. Therefore, A. dubius can become an alternative raw material for the formulation of feeds in tropical and subtropical countries where this plant is widespread.

Effects of Moringa oleifera leaves as a substitute for alfalfa meal on nutrient digestibility, growth performance, carcass trait, meat quality, antioxidant capacity and biochemical parameters of rabbits.

This contribution reports the effects of Moringa oleifera leaves (MOLs) meal on the growth performances, nutrient digestibility, carcass trait, meat quality, antioxidant capacity and biochemical parameters of growing New Zealand white rabbits. The MOL was substituted for alfalfa meal at levels of 0, 10%, 20% and 30% to obtain respective diets MOL0, MOL10, MOL20 and MOL30. Each treatment was replicated five times with 10 rabbits per replicate. Results showed the average daily weight gain (ADWG) and feed conversion ratio (FCR) of rabbits fed MOL20 diet were significantly better (p < 0.05) than those of other three dietary groups. Liver and spleen index of rabbits fed MOL20 and MOL30 diets was significantly higher (p < 0.05) than that of the groups fed with lower M. oleifera leaves (MOL0, MOL10). The meat drip loss of rabbits fed with diet MOL10 was significantly lower (p < 0.05) than that of rabbits fed other diets. All rabbits fed MOL dietary groups had lower (p < 0.05) shear force of longissimus dorsi than the group without M. oleifera leaves. No significant differences were found in the digestibility of crude fibre (CF), crude fat (EE), ash, crude protein (CP) and nitrogen-free extract (NFE) among the dietary groups. Moringa oleifera leaves also have a significant impact on serum albumin (ALB), low-density lipoprotein cholesterol (LDLC), triiodothyroxine (T3 ) and tetraiodothyroxine (T4 ) values and the activity of superoxide dismutase (SOD) and catalase (CAT) in serum and liver. The results indicated that M. oleifera leaves could be developed as a good feed source, and it not only could substitute for alfalfa meal well but also has a significant effect on growth performance, meat quality, antioxidant and biochemical parameters of rabbits.