Role of yeast cell wall polysaccharides in pig nutrition and health protection

Polysaccharides are the major components of the yeast cell wall and play multiple functions, ranging from the carriers of immunochemical specificity and marker molecules, by which cells recognize each other and interact with the environment, to the skeletal substances that define stability, shape, and morphology of the cell. In Saccharomyces cerevisiae, the two major polysaccharides, constituting up to 90% of the cell wall dry weight, are -d-mannan and β-d-glucan, which have remarkable properties to interact with the immune system of the host. Modulation of mucosal immunity by the binding of these two polysaccharides to the specific receptors of immune cells provides beneficial effects on animal health and resistance to diseases. Specific commercial yeast cell wall polysaccharides supplied in feed (Bio-Mos®, Alltech Inc.) are able to block fimbriae of pathogenic bacteria, and thus prevent their adhesion to the mucous epithelium. Since adhesion presents the first step in microbial invasion, blocking of the receptors may prevent or eliminate infection. Yeast cell wall polysaccharides are also able to adsorb mycotoxins, thus decreasing their toxic effect and mediating their removal from the organism. Commercial yeast polysaccharides (MTB100®, Alltech Inc.) have been shown to absorb a wide range of mycotoxins at low inclusion levels. Thus, especially if the ban on antibiotic growth promoters becomes global, use of yeast polysaccharides as natural growth stimulators becomes a very urgent and rewarding issue.     

沸石粉和酵母细胞壁对仔鸡黄曲霉毒素感染的防治作用

文章旨在评估两种吸附剂沸石粉与沸石粉+酵母细胞壁预防肉鸡黄曲霉毒素的效果。试验将550只1d肉仔鸡随机分为11组,每组5个重复,每个重复10只鸡。11个处理中包括3个没有添加吸附剂的日粮(含0、1和2mg/kg黄曲霉毒素B1),8个处理组日粮含1或2mg/kg黄曲霉毒素B1,添加沸石粉或沸石粉+酵母细胞壁。试验共持续21d。结果发现,随着日粮黄曲霉毒素B1水平的升高,肉鸡采食量、增重较对照组显著降低(P<0.05),肝脏重量较对照组显著提高(P<0.05)。在饲喂2mg/kg黄曲霉毒素B1日粮的仔鸡中观察到严重的肝脏损伤,病变与黄曲霉毒素病一致。日粮黄曲霉毒素B1污染显著降低了肉鸡血清葡萄糖、白蛋白、总蛋白、钙、磷含量和碱性磷酸酶活力(P<0.05)。1mg/kg黄曲霉毒素B1污染日粮中添加沸石粉或沸石粉+酵母细胞壁均可缓解毒素对肉鸡生长和肝脏病变的影响(P<0.05)。但2mg/kg黄曲霉毒素B1污染日粮中添加沸石粉+酵母细胞壁对毒素的影响无显著缓解效果,其中2mg/kg黄曲霉毒素B1污染日粮添加沸石粉的预防效果显著高于沸石粉+酵母细胞壁(P<0.05)。结果表明:日粮黄曲霉B1毒素污染显著降低了肉鸡的采食量、体增重,并导致高死亡率,同时导致肉鸡肝脏增大,肝功能受损。在本实验条件下,沸石粉和沸石粉+酵母细胞壁均能在较低黄曲霉毒素B1污染水平(1mg/kg)下有效缓解其负面影响,但沸石粉对2mg/kg黄曲霉毒素B1的缓解作用强于酵母细胞壁。     

Comparison of protection induced in lambs by Corynebacterium pseudotuberculosis whole cell and cell wall vaccines

Colostrum-deprived lambs were vaccinated IM with 10 mg (dry weight) of Corynebacterium pseudotuberculosis whole cells (WC) or cell walls (CW) and their immunity was challenged by IV injection of 3.1 X 10(4) colony-forming units of C pseudotuberculosis. Before challenge exposure, the logarithmic mean antibody titers were 2.0837 in lambs that were vaccinated with WC, 2.6858 in lambs that were vaccinated with CW, and 1.4214 in control lambs. Significant protection was demonstrated by fewer abscesses and organisms in the lungs of lambs vaccinated with WC or CW (P less than 0.05) than in control lambs. By the same criteria, more protection was provided to lambs vaccinated with CW than to lambs vaccinated with WC.     

Light and electron microscopy of keratinization in the laminar epidermis of the equine hoof with reference to laminitis

The laminar epidermis (epidermis parietis) of hooves from 14 clinically normal horses, 6 months to 15 years old, was examined by light and electron microscopy and immunofluorescence to measure the contributions of this region to the formation of the hoof wall. By their progressive keratinization to form primary epidermal laminae, the secondary epidermal laminae ultimately contributed about 20% of the thickness of the hoof wall (as revealed in the white line [zona alba]). The keratinized, primary epidermal laminae were developed to a height of 4 mm during their proximodistal-course, much of this obscured because of their basal portion being embedded in the cap horn epidermis. From evaluation of structural changes accompanying keratinogenesis in the cell and determination of the contribution of the laminar epidermis to the formation of laminar horn, cap horn, connecting horn, terminal horn, and the white line, we concluded that the sterile bed concept of a nongerminative role for the secondary epidermal laminae is no longer tenable.     

Influence of probiotic Lactobacilli colonization on neonatal B cell responses in a gnotobiotic pig model of human rotavirus infection and disease

The goal of this study was to define the impact of colonization of gnotobiotic (Gn) pigs with lactic acid bacteria (LAB) on development of intestinal and systemic B cell responses to human rotavirus (HRV). The LAB-specific and total B cell responses were also assessed. Gn pigs were inoculated with LAB (Lactobacillus acidophilus and L. reuteri) and virulent Wa strain HRV (LAB+HRV+), HRV only (LAB-HRV+), LAB only (LAB+HRV-) or mock (LAB-HRV-). The HRV infection induced similar HRV-specific intestinal and systemic antibody and B cell responses in pigs with or without LAB, whereas LAB significantly enhanced total intestinal IgA secreting cell responses and total serum IgM and intestinal IgM and IgG titers. The LAB colonization did not reduce HRV shedding or diarrhea, this may be partly due to the short time interval between the first LAB feeding and HRV inoculation. Further studies are needed with longer time for LAB to establish before HRV inoculation. However, our studies demonstrate that Gn pigs infected with HRV develop a similar magnitude of virus-specific B cell responses as those of HRV-infected and LAB colonized pigs. LAB colonization alone is not as efficient in promoting intestinal B cell responses, as is HRV infection.     

Detection of rotavirus in horses with and without diarrhea by electron microscopy and Rotazyme test

A total of 142 equine fecal samples (93 field fecal and 49 experimental fecal specimens) were examined for rotavirus using direct electron microscopy (EM) and the Rotazyme test. Eighty-six stool specimens were diarrhea samples. The Rotazyme test sensitivity and accuracy as compared to EM was determined by the visual (color reaction) and spectrophotometric methods. The overall agreement was 94.8% and 92.3% between EM and Rotazyme visual and spectrophotometric methods, respectively when suspect reactions (1 + color reaction or net absorbance between 0.05 and 0.1) were not included. The Rotazyme test is a quick, simple, and accurate diagnostic test for detection of rotavirus in equine fecal samples. It could be used by the equine practitioner with a minimum of laboratory facilities and by diagnostic and research laboratories.     

DNA synthesis in spinal ganglia of rabbit after Herpes suis infection. Findings obtained by electron microscopy and autoradiography]

The mulitplication of herpes suis virus in neurons, amphicytes, gliocytes, as well as Schwann's and endothelial cells of the spinal ganglion of rabbit was traced by electron microscopy and autoradiography, using tritium-labelled thymidine. Marking of nuclear zone margin, quite common when it comes to ganglion cells, was observed also in the context of mesenchymal cells beyond expectation on the basis of light microscopy, but in the case under review it had no direct relationship with virus synthesis. Repeated markings were recorded from the nucleoli of apparently unchanged ganglion cells which suggested the suitability of the technique for early detection of infectious attack on intact cells. Exogenous 3H-thymidine was supplied three hours and absorbed with specificity by the DNA-forming centres of the nuclei, but the growing virus drew into itself additional cellular or inactive thymidine. The method proved to be highly significant, as in comparison to the nuclear environment there were ten times as many lemnici in the DNA production centres of neurons and Schwann's cells and about six times as many in the amphicytes and gliocytes. Now, there is definite justification in rejecting as unfounded all doubt expressed repeatedly and more recently in the specificity of herpes-dependent intranuclear inclusions.     

Effects of Fusarium mycotoxins with yeast cell wall absorbent on hematology,serum biochemistry,and oxidative stress in broiler chickens

The objectives of the present study were to investigate the toxicity of feed-borne Fusarium mycotoxins on hematology, serum biochemistry, and oxidative stress of broiler chickens, and to evaluate the efficacy of yeast cell wall adsorbent (YCW) in preventing mycotoxins-induced adverse effects. A total of 300 one-day-old Arbor Acres broiler chickens (mixed sex) were randomly divided into 3 groups and received different treatments (5 repetitions per treatment). Treatments were control, naturally contaminated diet (NCD; aflatoxin, 102.08 mg/kg; zearalenone, 281.92 mg/kg; fumonisin, 5,874.38 mg/kg; deoxynivalenol, 2,038.96 mg/kg), and NCD + 2 g/kg of YCW. Broilers fed NCD showed elevated serum alanine transaminase, aspartate transaminase, alkaline phosphatase, γ-glutamyl transferase (GGT), and malondialdehyde (MDA) at 21 d, and alanine transaminase, GGT, creatine kinase, and MDA at 42 d. Higher white blood cell, lymphocyte (LYM), platelet, red blood cell, hemoglobin, hematocrit, and mean corpuscular hemoglobin counts at 21 d, as well as LYM in whole blood and hepatic mRNA expression of heat shock protein 70 at 42 d were also observed in broilers fed with NCD compared with the control diet. However, lower mean corpuscular volume at 42 d and total superoxide dismutase (T-SOD) at both 21 and 42 d were observed in broilers with the NCD treatment when compared with those with the control treatment. Dietary addition of YCW at the level of 2 g/kg in addition to the NCD treatment showed a positive protective effect on GGT, T-SOD in serum, white blood cells, LYM, platelets, and hemoglobin in whole blood at 21 d, and T-SOD, MDA in serum, LYM, mean corpuscular volume in whole blood, and hepatic mRNA expression of heat-shock protein 70 at 42 d. It is suggested that feeding NCD for 42 d might result in a deleterious effect on broiler chickens, and addition of 2 g/kg of YCW can partly attenuate the detrimental effects of the NCD feeding.     

Comparison of the prevalence of enteric viruses in healthy dogs and those with acute haemorrhagic diarrhoea by electron microscopy

Objectives: To evaluate prevalence of enteric viruses in healthy dogs and to compare it with prevalences in dogs with acute haemorrhagic diarrhoea. Methods: Faecal samples were collected from 200 healthy dogs and examined by electron microscopy for presence of viral particles. Data were compared with viral prevalences that had been determined retrospectively by electron microscopy for 936 dogs with acute haemorrhagic diarrhoea. Results: There were significantly more negative faecal samples among the healthy dogs (82.0 per cent) compared with 55.8 per cent in dogs with acute haemorrhagic diarrhoea (P<0.001). With a prevalence of 17.5 per cent, significantly more healthy dogs were shedding coronavirus compared with 11.6 per cent in dogs with acute haemorrhagic diarrhoea (P=0.034). Parvovirus was only detected in one healthy dog (0.5 per cent), thus with a prevalence that was significantly lower than 16.0 per cent detected in the dogs with acute haemorrhagic diarrhoea (P<0.001). Paramyxovirus was not found in any of the healthy dogs but was found in 9.3 per cent of dogs with acute haemorrhagic diarrhoea (P<0.001). Clinical Significance: Results suggest that shedding of parvovirus and paramyxovirus is strongly associated with acute haemorrhagic diarrhoea. However, coronavirus seems to be even more prevalent among healthy dogs, raising the need for further studies to investigate the strain-associated pathogenicity of this virus.     

Depiction of the structure of the vitreous body in horses without ocular diseases and in horses with equine recurrent uveitis (ERU) using transmission electron microscopy

Neither the ultrastructure of the vitreous body from horses without ocular diseases, nor the pathomorphological changes in the vitreous body associated with equine recurrent uveitis (ERU) have been described. However, the vitreous body plays an important role in the pathogenesis of ERU. Ten vitreous body samples obtained from 5 horses without ocular disease, and 38 vitreous body samples from horses with ERU (collected during vitrectomy) were examined by transmission electron microscopy. The vitreous body samples of horses without ocular diseases were characterized by a loose network of unbranched fibrils 10-12 nm in width. In the vitreous body samples of horses with ERU numerous dense bundles of fibrils, mononuclear inflammatory cells and necrotic cells represent the destruction of the vitreous fibrillar network. In this study, equine vitreous body ultrastructure was described for the first time. Thus, demonstrating ultramorphologically, the clinically apparent changes of the vitreous body associated with ERU.     

Peptic ulceration in a dog associated with an islet cell carcinoma of the pancreas and an elevated plasma gastrin level

The history, clinical signs and post-mortem findings in a 6-year-old, male, Boxer dog with peptic ulceration and a tumour derived from islet cells of the pancreas are described. The immunoreactive circulating plasma gastrin in this dog was elevated and measured 360 pg/ml (normal range 23–104 pg/ml). The findings in this dog are similar to those described for Zollinger-Ellison syndrome in man. It is possible that the pathogenesis of peptic ulceration in this case is similar to that of Zollinger-Ellison syndrome.     

Identification of a mutant bovine herpesvirus-1 (BHV-1) in post-arrival outbreaks of IBR in feedlot calves and protection with conventional vaccination.

Outbreaks of infectious bovine rhinotracheitis (IBR) have recently been observed in vaccinated feedlot calves in Alberta a few months post-arrival. To investigate the cause of these outbreaks, lung and tracheal tissues were collected from calves that died of IBR during a post-arrival outbreak of disease. Bovine herpesvirus-1 (BHV-1), the causative agent of IBR, was isolated from 6 out of 15 tissues. Of these 6 isolates, 5 failed to react with a monoclonal antibody specific for one of the epitopes on glycoprotein D, one of the most important antigens of BHV-1. The ability of one of these mutant BHV-1 isolates to cause disease in calves vaccinated with a modified-live IBR vaccine was assessed in an experimental challenge study. After one vaccination, the majority of the calves developed humoral and cellular immune responses. Secondary vaccination resulted in a substantially enhanced level of immunity in all animals. Three months after the second vaccination, calves were either challenged with one of the mutant isolates or with a conventional challenge strain of BHV-1. Regardless of the type of virus used for challenge, vaccinated calves experienced significantly (P < 0.05) less weight loss and temperature rises, had lower nasal scores, and shed less virus than non-vaccinated animals. The only statistically significant (P < 0.05) difference between the 2 challenge viruses was the amount of virus shed, which was higher in non-vaccinated calves challenged with the mutant virus than in those challenged with the conventional virus. These data show that calves vaccinated with a modified-live IBR vaccine are protected from challenge with either the mutant or the conventional virus.     

Effects of a dietary application of a yeast cell wall extract on innate and acquired immunity, on oxidative status and growth performance in weanling piglets and on the ileal epithelium in fattened pigs

Potential immunomodulatory effects of a cell wall extract from Saccharomyces cerevisiae (Y; Antaferm MG) were tested in pigs: in trial I, 0.03% Y and in trial II 0.3% Y was used. Based on earlier observations that Y may increase feed intake, two treatment groups, Y-a (fed ad libitum) and Y-r (fed restrictively) were studied in comparison with a control group (C) in both trials. Y-r received the amount of feed consumed by C. Immune status was surveyed by determining phagocytic activity and oxidative burst of neutrophils and blood concentrations of haptoglobin (Hp), and immunoglobulin (Ig) G and A. Oxidative stress was monitored by recording reactive oxygen metabolites (ROM) and total antioxidant capacity. In a third trial, fattened pigs were used for morphological and immunohistochemical studies (IgM and IgA as well as CD4(+) and CD8(+) T cells) in ileal epithelium. Pigs fed 0.03% Y for 2 weeks prior to slaughter were compared with the C group. Feed intake was identical in the Y-a and Y-b groups and data subsets were accordingly pooled. Treatment and time as well as treatment x time interactions were detectable for most of the parameters studied, but a distinct immunomodulatory effect of Y was not consistently identifiable and performance did not improve. In trial III, the intestinal parameters investigated were not different between Y and C.     

Characterization of protection against systemic infection and disease from experimental bovine viral diarrhea virus type 2 infection by use of a modified-live noncytopathic type 1 vaccine in calves

OBJECTIVE: To evaluate protection resulting from use of a modified-live noncytopathic bovine viral diarrhea virus (BVDV) type 1 vaccine against systemic infection and clinical disease in calves challenged with type 2 BVDV. ANIMALS: 10 calves, 5 to 7 months of age. PROCEDURES: Calves were allocated (n = 5/group) to be nonvaccinated or vaccinated SC on day 0 with BVDV 1 (WRL strain). Calves in both groups were challenged intranasally with BVDV type 2 isolate 890 on day 21. Rectal temperatures and clinical signs of disease were recorded daily, and total and differential WBC and platelet counts were performed. Histologic examinations and immunohistochemical analyses to detect lesions and distribution of viral antigens, respectively, were performed. RESULTS: After challenge exposure to BVDV type 2, nonvaccinated calves developed high rectal temperatures, increased respiratory rates, viremia, leukopenia, lymphopenia, and infection of the thymus. Vaccinated calves did not develop high rectal temperatures or clinical signs of respiratory tract disease. Vaccinated calves appeared to be protected against systemic replication of virus in that they did not develop leukopenia, lymphopenia, viremia, or infection of target organs, and infectious virus was not detected in peripheral blood mononuclear cells or the thymus. CONCLUSIONS AND CLINICAL RELEVANCE: The modified-live BVDV type 1 vaccine protected against systemic infection and disease after experimental challenge exposure with BVDV type 2. The vaccine protected calves against infection and viremia and prevented infection of target lymphoid cells.