Efficiency Of Rabbits Research Articles

Transcriptome analysis of divergent residual feed intake phenotypes in the M. longissimus thoracis et lumborum of Wannan Yellow rabbits

Introduction: Feed efficiency is an important economic trait in rabbit meat production. The identification of molecular mechanisms and candidate genes for feed efficiency may improve the economic and environmental benefits of the rabbit meat industry. As an alternative to the conventional feed conversion ratio, residual feed intake (RFI) can be used as an accurate indicator of feed efficiency.Methods: RNA sequencing was used to identify the differentially expressed genes (DEGs) in the M. longissimus thoracis et lumborum of eight Wannan Yellow rabbits with excessively high or low RFIs (HRFI or LRFI, respectively). Thereafter, Gene Ontology (GO) analysis, enrichment using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, gene set enrichment analysis (GSEA), and protein–protein interaction (PPI) network analysis was conducted.Results: In total, 445 DEGs were identified in the M. longissimus thoracis et lumborum of rabbits with high and low RFIs. The significantly enriched GO terms identified in these two groups were primarily involved in energy and mitochondrial metabolism and oxidation–reduction processes. KEGG analysis identified 11 significantly enriched pathways, including oxidative phosphorylation, PI3K-Akt signaling, and extracellular matrix-receptor interaction pathways. According to GSEA, the expressions of genes and pathways related to mitochondrial function were upregulated in HRFI rabbits, whereas genes with upregulated expressions in LRFI rabbits were related to immune response and energy metabolism. Additionally, PPI network analysis revealed five potential candidate genetic markers.Conclusion: Comparative analysis of the M. longissimus thoracis et lumborum transcriptomes in HRFI and LRFI rabbits revealed FOS, MYC, PRKACB, ITGA2, and FN1 as potential candidate genes that affect feed efficiency in rabbits. In addition, key signaling pathways involved in oxidative phosphorylation and PI3K-Akt and ECM-receptor interaction signaling impact rabbit feed efficiency. These findings will aid in breeding programs to improve feed efficiency and optimize RFI selection of rabbits for meat production.

Genome wide association study of growth and feed efficiency traits in rabbits

Feed efficiency is a major production trait in animal genetic breeding schemes. To further investigate the genetic control of feed efficiency in rabbits, we performed a genome-wide association study (GWAS) for growth and feed efficiency on 679 rabbits genotyped with the Affimetrix Axiom Rabbit 200K Genotyping Array. After quality control, 127 847 single-nucleotide polymorphisms (SNP) were retained for association analyses. The GWAS were performed using GEMMA software, applying a mixed univariate animal model with a linear regression on each SNP allele. The traits analysed were weight at weaning and at 63 days of age, average daily gain, total individual feed intake, feed conversion ratio and residual feed intake. No significant SNP was found for growth traits or feed intake. Fifteen genome-wide significant SNPs were detected for feed conversion ratio on OCU7, spanning from 124.8 Mbp to 126.3 Mbp, plus two isolated SNP on OCU2 (77.3 Mbp) and OCU8 (16.5 Mbp). For residual feed intake, a region on OCU18 (46.1-53.0 Mbp) was detected, which contained a putative functional candidate gene, GOT1.

Evaluation of anti‐tick efficiency in rabbits induced by DNA vaccines encoding Haemaphysalis longicornis lipocalin homologue

Haemaphysalis longicornis is an obligate haematophagous ectoparasite, transmitting a variety of pathogens, which brings great damage to human health and animal husbandry development. Lipocalins (LIP) are a family of proteins that transport small hydrophobic molecules and also involve in immune regulation, such as the regulation of cell homeostasis, inhibiting the host's inflammatory response and resisting the contractile responses in host blood vessels. Therefore, it is one of the candidate antigens for vaccines. Based on previous studies, we constructed the recombinant plasmid pcDNA3.1-HlLIP of LIP homologue from H. longicornis (HlLIP). ELISA results showed that rabbits immunized with pcDNA3.1-HlLIP produced higher anti-rHlLIP antibody levels compared with the pcDNA3.1 group, indicating that pcDNA3.1-HlLIP induced the humoral immune response of host. Adult H. longicornis infestation trial in rabbits demonstrated that the engorgement weight, oviposition and hatchability of H. longicornis fed on rabbits immunized with pcDNA3.1-HlLIP decreased by 7.07%, 14.30% and 11.70% respectively, compared with that of the pcDNA3.1 group. In brief, DNA vaccine of pcDNA3.1-HlLIP provided immune protection efficiency of 30% in rabbits. This study demonstrated that pcDNA3.1-HlLIP can partially protect rabbits against H. longicornis, and it is possible to develop a new candidate antigen against ticks.

Evaluation of room temperature (30°C to 35°C) lyophilized vaccine with radio inactivated Mannheimia haemolytica whole cells isolated from infected sheep.

Background and Aim:Vaccines are one of the important tools for fighting diseases and limiting their spread. The development of vaccines with high efficacy against diseases is essential. Ionizing radiation is the method used for the preparation of the irradiated gamma Mannheimia haemolytica vaccine. The study aimed to measure the metabolic activity and electron microscopic examination of the irradiated bacterial cells and immunological efficiency of different preparations of the irradiated M. haemolytica vaccine.Materials and Methods:The irradiated vaccines were prepared in three forms at a dose of 2×109 colony-forming unit (CFU) (irradiated M. haemolytica, trehalose irradiated M. haemolytica, and trehalose lyophilized irradiated M. haemolytica). The formalin-killed vaccine was prepared at a dose of 2×109 CFU. Scanning electron microscopy was used to determine the difference between the non-irradiated bacterial cells and the bacterial cells exposed to gamma radiation. The metabolic activity of the irradiated bacterial cells was measured using the Alamar blue technique. Rabbits were divided into five groups (control, vaccinated groups with the formalin-killed vaccine, irradiated bacterial cells without trehalose, trehalose irradiated bacteria, and trehalose lyophilized irradiated bacterial cells). The rabbits were subcutaneously inoculated twice in 2-week intervals. Enzyme-linked immunosorbent assay, interferon-gamma (IFNγ), and interleukin 4 (IL4) assays were used to evaluate the vaccines’ immunological efficiency in rabbits.Results:The metabolic activity tests showed that the bacterial cells exposed to gamma radiation at the lowest lethal dose have metabolic activity. The difference in the metabolic activity between preparations of the irradiated bacterial cells varied according to the cell concentration and incubation time. The highest level of metabolic activity was 8 h after incubation in the nutrient broth medium compared with 4 and 18 h. The scanning electron microscopy of irradiated bacterial cells showed a cavity at the bacterial cell center without rupture of the surrounding cell membrane compared to the non-irradiated bacterial cells. The antibody level in the groups vaccinated with the different preparations of the irradiated bacterial cells was high compared with the control and formalin-killed vaccine groups. The level of the IFNγ showed an increase after the second dose in the group vaccinated with irradiated bacterial cells without trehalose compared with the other groups. The IL4 level in the vaccinated groups with the irradiated bacterial cells without trehalose, irradiated bacterial cells with trehalose, and trehalose lyophilized irradiated bacterial cells were at a high level when compared with the formalin-killed vaccinated group and control group after the second inoculation.Conclusion:The irradiated M. haemolytica vaccine provides a wide range of humoral and cellular immunity. This study showed high immunological efficiency in rabbits inoculated with the irradiated M. haemolytica vaccine that was shown in the high levels of antibodies (IFNγ and IL4) compared with the group treated with the formalin-killed vaccine. The second dose of irradiated M. haemolytica vaccine is an immune booster that gives the irradiated vaccine a long-acting immunological efficiency.

Efficiency of meat-fattening rabbits farmed by different keeping technologies

In Russia, different technologies are used for keeping commercial young animals in the production of rabbit meat. The main ones are in rooms with a controlled microclimate (imported young rabbits) and sheds (domestic breeds). The aim of the study was to establish the dominant factors that determine efficiency of rabbit meat production under different keeping technologies and dry feeding. Experimental studies were conducted according to classical zootechnical methods. The experiment in the room with controlled conditions was carried out on crossbred young animals - f rom Californian and New Zealand white breeds, which were imported from France in 2010; the experiment on domestic breed - Soviet chinchilla - was carried out under shed keeping technology. During the fattening period all rabbits were fed with complete granulated compound feed with an identical ratio of nutrients: 16.0 % protein and 17.5 % fiber for crossbred rabbits; 16.4 % protein and 17.9 % fiber for Soviet chinchilla rabbits. Slaughter of Soviet chinchilla rabbits and crossbred rabbits for meat was carried out at the age of 90 and 77 days, respectively. Analysis of the dynamics of live weight showed that at the age of 45 days and at the time of slaughter crossbred young rabbits exceeded Soviet chinchilla rabbits by 204.5 g and 240.0 g, respectively. Meanwhile, the relative growth of crossbred rabbits was not much higher than this indicator in Soviet chinchilla rabbits (by 3.4 and 4.1 %, respectively). The pre-slaughter weight was also significantly higher in crossbred animals, and the carcass weight was significantly higher in Soviet chinchilla rabbits. Accordingly, in the Soviet chinchilla the slaughter yield was 9.2 % higher than that of the crossbred rabbits, that is in meat production in the Soviet chinchilla more organic matter goes into products and less to waste. This testifies to the fact that by the age of 77 days the crossbred rabbits did not realize their full meat potential. Thus, considering the increased energy costs in buildings with a controlled microclimate, both technologies for keeping commercial young rabbits have the same chances in the production of rabbit meat.

Dietary Plukenetia conophora seed alters muscle cholesterol, antioxidant enzymes, and fatty acids in growing rabbits

The influence of dietary inclusion of Plukenetia conophora seed (PCS) on growth, carcass, muscle antioxidant enzymes, fatty acids, meat quality, and sensory attributes of Longissimus thoracis et lumburum muscle in rabbits was examined. Seventy-two, 28 d old male New Zealand rabbits (750 ± 20 g) were randomly allotted to diets containing either no PCS (PCS-0), 2.5% PCS (PCS-2.5) or 5% PCS (PCS-5) for eight weeks, and euthanized. PCS-5 rabbits had higher (P < 0.05) body and carcass weights than the PCS-0 rabbits. Dietary PCS improved feed efficiency in rabbits. Muscle antioxidant enzymes activities and total phenols were higher while muscle cholesterol was lower (P < 0.05) in supplemented meat than the PCS-0 meat. The concentration of C22:6n-3, C20:5n-3 and C18:3n-3 was higher (P < 0.05) in the supplemented meat than the PCS-0 meat. Sensory attributes, carbonyl, and TBARS values and physicochemical properties of meat did not differ among diets. Supplementation of PCS-5 enhances muscle n-3 fatty acids without impairing the sensory properties, and oxidative stability of rabbit meat.

Efficient base editing with high precision in rabbits using YFE-BE4max

Cytidine base editors, composed of a cytidine deaminase fused to Cas9 nickase, enable efficient C-to-T conversion in various organisms. However, current base editors suffer from severe trade-off between editing efficiency and precision. Here, based on rationally mutated cytidine deaminase domain, we develop a new base editor, YFE-BE4max, effectively narrow the editing width to as little as approximately three nucleotides while maintaining high efficiency in rabbits. Moreover, YFE-BE4max successfully mediated the Tyr p. Q68Stop and Lmna p. G607G mutation in F0 rabbit with high efficiency and precision, which precisely recapitulates the pathological features of human OCA1 and HGPS, respectively. Collectively, YFE-BE4max system provide promising tools to perform efficient base editing with high precision in rabbits and enhances its capacity to precisely model human diseases.

Influence of four tropical medicinal and aromatic plants on growth performance, digestibility, and blood constituents of rabbits

The present context was aimed to assess the influence of medicinal and aromatic plants supplemented diets on growth performance, digestibility, blood serum constituents, and economic efficiency of rabbits (Oryctolagus cuniculus L.) as a model of livestock animals. A total of forty New Zealand White (NZW) male rabbits of 6 weeks of age with an average initial body weight of 837.7 ± 42.4 g were used. Rabbits were distributed into 5 groups (8 rabbits per group). First group served as control (non-supplemented diet), while P1, P2, P3, and P4 groups were supplemented with 1% basil (Ocimum basilicum L.), chamomile flower (Matricaria chamomilla L.), fennel (Foeniculum vulgare Mill.), and ginger (Zingiber officinale L.), respectively. The final body weight (13 weeks of age), daily weight gain, daily feed intake, performance index, and feed conversion ratio were increased (P < 0.05) in rabbits fed diet supplemented with fennel (i.e., P3). Digestibility and feeding values were higher (P < 0.05) for P2 and P3 rabbits. Rabbits fed diets supplemented with P1, P2, and P3 excreted higher (in P3) and lower (in P1 and P2) crude protein in soft and hard feces, respectively. Control and P4 group showed the highest (P < 0.05) crude fiber content of soft feces when compared to other groups tested. Most of the carcass traits and blood parameters were significantly (P < 0.05) affected by rabbits fed diet supplemented with P3. Results indicated that 1% fennel could be preferably supplemented in growing rabbit’s basal diets for their enhanced productive performance, economical efficiency, and other essential livestock parameters.

Effect of dietary soluble fibre and n-6/n-3 fatty acid ratio on growth performance and nitrogen and energy retention efficiency in growing rabbits

The aim of this work was to study whether the dietary supplementation with soluble fibre (SF) and the reduction of the n-6/n-3 fatty acid ratio or the combination of both influence the growth performance and digestible nitrogen and energy (DN and DE) retention efficiency in rabbits from 27 to 62 d of age. Four diets in a 2 × 2 factorial arrangement were used with two levels of SF (7.8 vs. 13.0%, on DM basis, LSF vs. HSF) and two different n-6/n-3 ratio (13.4/1 vs. 3.5/1, Hn-6/n-3 vs. Ln-6/n-3). Nitrogen and energy retention in the body and in the carcass were determined by bioelectrical impedance. The increase of SF reduced the mortality (38.3 vs. 24.1%; P = 0.018), with no effect of the n-6/n-3 ratio. The feed efficiency in the whole experimental period (27–62 d of age) improved with the increase of the level of SF (+3.5%; P = 0.003) and the reduction of the n-6/n-3 (+2%; P ≤ 0.048). The increase of SF decreased the ratio DN/DE (-2%; P = 0.035). The increase of SF and the reduction of the n-6/n-3 ratio reduced the DN intake (-4%. P ≤ 0.030). However, the amount of nitrogen retained in the body or in the carcass was not affected by treatments (P ≥ 0.26). Consequently, the increase of dietary SF and the reduction of the n-6/n-3 ratio improved the retention of DN in the body and in the carcass (between 3.4 and 5.4%. P ≤ 0.017). It was associated with a reduction of the urinary nitrogen excretion in HSF respect to LSF groups (−13%; P = 0.004) and in Ln-6/n-3 respect to Hn-6/n-3 groups (-12%; P = 0.006). In contrast, the increase of SF increased the faecal nitrogen excretion (+5%; P = 0.004). Treatments had no effect on DE intake and on body and carcass energy retention (P ≥ 0.13). The increase of SF improved the body and carcass DE retention efficiency (+3%. P ≤ 0.042). It was mainly due to the impairment observed in rabbis fed LSF_Hn-6/n-3 respect to those fed LSF_Ln-6/n-3 diet (P = 0.071). In conclusion, the increase of SF improved the survival of fattening rabbits, with no influence of the n-6/n-3 ratio, and both factors especially improved the efficiency of DN but also the DE retained in the body and in the carcass.

Performance of growing rabbits fed increasing levels of discarded Salvia hispanica L. (chia) seed

This experiment was carried out to evaluate the effect of including five levels of discarded chia seed (DCS) on growth, energy, and economic efficiency in rabbits. Fifty crossbred (New Zealand × Californian) weaning rabbits, weighing 798 ± 170g, were randomly assigned to the following treatments: 0% (control), 10% (Ch10), 20% (Ch20), 30% (Ch30), and 40% (Ch40) of DCS. Ten unsexed rabbits were allocated to each treatment and housed individually in cages; the experimental period was 6weeks. There were no statistically significant differences between treatments in final body weight (2050g), body weight gain (30g/rabbit/day), and carcass weight (1010g); however, feed intake (91g/rabbit/day in Ch20 vs. 80g/rabbit/day in Ch40), feed conversion ratio (2.77 in control and Ch40 vs. 2.95 in Ch10, Ch20, and Ch30), energy conversion ratio (32MJ/kg in Ch20 vs. 29MJ/kg on average in control, Ch10, Ch20, Ch30, and Ch40), and economic efficiency (358% in control vs. 433% in Ch40) showed differences (P < 0.05) between treatments. Discarded chia seed can be included up to 40% in growing rabbit diets without any adverse effects on growth and carcass weight, and increased economic efficiency.

Synergistic effect of trichostatin A and scriptaid on the development of cloned rabbit embryos

The first successful rabbit SCNT was achieved more than one decade ago, yet rabbits remain one of the most difficult species to clone. The present study was designed to evaluate the effects of two histone deacetylase inhibitors (HDACis), namely trichostatin A (TSA) and scriptaid (SCP), on cloning efficiency in rabbits. The in vitro development, acetylation levels of histone H4 lysine 5 (H4K5), and octamer-binding transcription factor 4 (Oct-4) expression patterns of cloned embryos were systemically examined after various HDACi treatments. Supplementation of TSA (50 nM) or SCP (250 nM) in the culture medium for 6 hours improved blastocyst development rates of cloned embryos compared with the treatment without HDACi. The combined treatment with TSA (50 nM) and SCP (250 nM) further enhanced morula (58.6%) and blastocyst (49.4%) rates in vitro. More importantly, compared with single HDACi treatments, embryos with the combined treatment had a higher level of H4K5 and an increased total cell number (203.7 ± 14.4 vs. 158.9 ± 9.0 or 162.1 ± 8.2; P < 0.05) with a better Oct-4 expression pattern in hatching blastocysts, indicating substantially improved embryo quality. This was apparently the first report regarding Oct-4 expression in cloned rabbit embryos. We inferred that most cloned rabbit embryos had an aberrant inner cell mass (ICM) structure accompanied with abnormal spatial distribution of Oct-4 signals. This study demonstrated a synergistic effect of TSA and SCP treatments on cloned rabbit embryos, which might be useful to improve cloning efficiency in rabbits.

The camp analogue, dbcAMP can stimulate rabbit reproductive functions: I. Effect on ovarian folliculogenesis, ovulation and embryo production

The aim of our study was to examine the influence of administration of N6,2’-dibutyryladenosine 3’5’-cyclic monophosphate (dbcAMP), a cAMP agonist, on ovarian folliculogenesis and atresia, as well as on reproductive efficiency in rabbits, whose ovarian cycle and ovulation was induced by gonadotropins. Ovarian cycle and ovulation of control rabbits were induced by 20 IU/kg PMSG followed by 35 IU/kg hCG administration. Experimental animals received PMSG and hCG together with dbcAMP (at 5, 25 or 50 μg/animal). After ovulation and insemination, the animals were sacrificed. Ovaries were weighted, histological sections of ovaries were prepared, and the presence of ovulated and not ovulated follicles and different stages of atresia was evaluated by light microscopy. The eggs were flushed from the oviducts after insemination and cultured up to blastocyst cell stage. Numbers of ovarian Corpora lutea, ovulated oocytes and oocyte-derived zygotes and embryos reaching hatched blastocyst stage were determined. Administration of dbcAMP (at doses 25 or 50 μg/animal, but not at 5 μg/animal) was able to increase the proportion of follicles with cystic and luteinization-related atresia. Furthermore, dbcAMP (50 μg/animal, but not lower doses) increased the ovarian mass, number of Corpora lutea, number of harvested oocytes, zygotes and embryos at blastocyst stage derived from these zygotes after culture. These data demonstrate that dbcAMP can stimulate rabbit ovarian follicle atresia, ovulation, oocyte, zygote and embryo yield and development. Furthermore, they confirm in the involvement of cyclic nucleotide-dependent intracellular mechanisms in the control of rabbit reproductive functions and potential practical usefulness of dbcAMP in improving animal reproduction and fertility.

Technical Efficiency of Small-Scale Rabbit Production in South-West, Nigeria

This study examines technical efficiency of rabbit rearing in South-west Nigeria. Data were collected from 150 rabbit farmsteads across states in the South-West Nigeria. The Cobb-Douglas Stochastic Production Frontier Functions were used to analyse the study data. Stochastic Production Frontier Function estimates showed that labour, size of rabbit operating stock and the type of feed fed to rabbits: either commercial feeds or kitchen and other rabbit edible wastes were contributing to revenues that accrue to rabbit rearing. However, the quantity of forage fed to rabbits did not show any influence. The inefficiency estimate indicates that rabbit mortality act as a deterrent to TE in rabbit production while rabbit farmer education and experience were contributing to technical efficiency TE. The study therefore calls for researches on rabbit health and disease control vis-a-vis the local condition under which rabbit are raised and the need to educate farmers on rabbit production techniques. Key Words : Rearing, Productive, Returns to Scale, Cobb-Douglas Stochastic Production Frontier Function, Farmstead

Genetic selection of maternal lines and digestive efficiency in rabbits: long term selection for litter size at weaning versus hyper selection for reproductive longevity.

The objective of the present paper is to evaluate how long-term selection for litter size at weaning or short-term hyper selection for reproductive longevity, affect the digestive utilisation of growing and lactating rabbits. A digestibility trial was carried out during the 3rd week of lactation with a total of 27 multiparous does: 14 females came from a line selected for litter size at weaning over 32 generations (V), and 13 from a recently constituted, long lived-productive line (LP). Another digestibility trial was performed during the growing period with a total of 48 growing rabbits (24 from each line). After a 7 d adaptation period, faeces were collected individually for 4 d (from 13 to 16 d of lactation or from 49 to 53 d of age, respectively). Daily feed intake and weight gain recorded during the experimental growing period were similar for both lines (137 g of dry matter (DM)/d and 48 g/d, respectively). Growing rabbits from the V-line showed greater values for the digestibility of the DM and OM (+1 percentage point; P&lt;0.10) and signifi cantly higher values for the acid detergent fi bre (+3 percentage points; P=0.03) than animals from the LP line. No signifi cant differences for the apparent digestibility coeffi cients of crude protein, neutral detergent fi bre, crude fi bre and gross energy were observed between lines, these being on average 65.7, 23.0, 10.7 and 52.6%, respectively. Females from the LP line were initially heavier (+258 g of live weight; P=0.06), and presented a signifi cantly greater daily feed intake (+22 g DM/d; P=0.04) and milk yield (+37 g/d; P=0.01) during the pre-experimental and faeces collection phases (from 6 to 16 d of lactation). V-line lactating does displayed greater values for digestibility for all those nutrients evaluated (from +0.9 and +3.7 percentage points for the crude protein and acid detergent fi bre) compared to the LP line females, although these were only signifi cant for the DM, organic matter and gross energy (+2.3, +2.5, +2.1 percentage points; P&lt;0.05). In conclusion, rabbits selected for litter size at weaning seem to have greater effi ciency for digestive utilisation than those hyper selected for reproductive longevity.

Comparative analysis of the effect of endogenous antibiotic defensin NP-1 and aminoglycoside antibiotic gentamicin on synaptic transmission in receptors of the frog vestibular apparatus

The effect of human and rabbit neutrophilic defensins NP-1 and amonoglycoside antibiotic gentamicin on the synaptic transmission in the afferent synapse of isolated vestibular apparatus of the frog has been comparatively studied. Both defensins proved active in the concentration range of 0.0001 to 1 nM and efficiently decreased the impulse frequency in the afferent nerve fibers in a concentration-dependent manner. No significant differences in the efficiency of rabbit and human defensin NP-1 have been revealed in these experiments. Gentamicin also had an inhibitory effect on the afferent discharge in the concentration range of 10-500 microM (0.5-25 mg/kg). The inhibitory effect of gentamicin on the impulse activity of the vestibular nerve was observed at therapeutic doses. The excitatory effect of the putative neurotransmitter L-glutamate was considerably inhibited by defensin NP-1. These findings suggest that the mechanism of defensin action involves a modification of the synaptic transmission the hair receptor and is mediated by L-glutamate.

Effect of feeding raw and cooked &lt;I&gt;Leucaena leucocephala&lt;/I&gt; seed bean based diets on the performance of rabbits

The effect of Leucaena leucocephala seed meal as a feed supplement on the growth of weaning rabbits was studied. The raw and cooked Leucaena leucocephala seeds contained (DM basis): crude protein 20.46% and 24.64%, crude fibre 20.48% and 26.72%, ether extract 9.84% and 10.40% respectively. The seed was tested at 10% level of the diet. The body weight gain, feed intake and feed efficiency of rabbits fed with cooked Leucaena leucocephala diet were higher by 24.12 and 28.72%, 19.6 and 8.31%, 10.38 and 10.69% respectively than those rabbits fed with control and raw Leucaena leucocephala diets. Key Words: Leucaena leucocephala; performance; rabbits; raw and cooked diets Moor J. Agric. Res. Vol.4(1) 2003: 135-139

Experimental study of double-lumen, two-stage endotracheal tube during conventional mechanical ventilation in rabbits.

To evaluate the effects of a double-lumen, two-stage endotracheal tube on gas exchanges (ventilatory efficiency) during conventional mechanical ventilation, using a ventilator in rabbits. Prospective, randomized, crossover laboratory animal trial. Research laboratory in the Beijing Children's Hospital. Five adult New Zealand rabbits, weighing 3.2 to 3.7 kg. A new type of endotracheal tube-the double-lumen two-stage endotracheal tube-was designed and tested for ventilation efficiency in rabbits with normal and injured lungs. The new tube (size 3.0 mm) was made out of two Portex endotracheal tubes (size 3.0 mm) by adhering two vertical cross-sections at the distal end of the two tubes. The new tube and a conventional endotracheal tube of the same size (inner diameter 3.0 mm) were randomly used in pressure control ventilation. Each trial was maintained for 30 mins. Effects from the two endotracheal tubes on pulmonary mechanics, hemodynamics, and gas exchange were observed. We measured peak inspiratory pressure, positive end-expiratory pressure (PEEP), intrinsic PEEP, mean airway pressure, and arterial blood and mixed expired gas variables (Pao2, Paco2, pH, and mixed expired gas Pco2). The new endotracheal tube acutely increased CO2 elimination in all animals with normal and injured lungs. Paco2 decreased from 46 +/- 4 to 36 +/- 5 torr (6.1 +/- 0.5 to 4.8 +/- 0.7 kPa; p < .01) in normal lungs and from 48 +/- 5 to 36 +/- 5 (6.4 +/- 0.7 to 4.8 +/- 0.7 kPa; p < .01). Meanwhile, tidal volume fraction decreased from 0.48 +/- 0.07 to 0.35 +/- 0.05 (p < .01) and from 0.56 +/- 0.07 to 0.40 +/- 0.07 (p < .01) in normal and injured lungs, respectively. Intrinsic PEEP of the new tube slightly increased, but there were no significant differences in comparison with the conventional tube. Compared with the conventional endotracheal tube, the new double-lumen, two-stage endotracheal tube reduced Paco2 by decreasing anatomical deadspace in rabbits with normal and injured lungs under pressure control ventilation, thus enhancing ventilatory efficiency and reducing ventilator-induced injury.

Improved transgenic efficiency in rabbits attributed to successful microinjection, embryo transfer and animal husbandry procedures

Improved transgenic efficiency in rabbits attributed to successful microinjection, embryo transfer and animal husbandry procedures