Minimum inhibitory concentrations of intestinal Escherichia coli from broiler chickens after oral administration of apramycin

This study describes the influence of apramycin on minimum inhibitory concentrations (MIC) of intestinal Escherichia coli in young broiler chickens, after oral administration of the antibiotic at a dosage equivalent to a prophylactic course of treatment for 10 d. The bacteria were isolated from cloacal swabs and caecal contents. MICs were determined by agar dilution procedures. MIC of apramycin for the investigated strains ranged from 1 μg ml^-1 to 16 μg ml^-1. Strains obtained from undosed birds mainly had MIC values of 1 μg ml^-1. MIC values of 8 μg ml^-1 or more were recorded only among isolates obtained from chickens which had received apramycin. Administration of apramycin resulted in a slight but statistically significant increase in the average MIC. Statistically higher average MICs were recorded among isolates from cloacal swabs 10 d after withdrawal until the end of the experiment. For strains from caecal contents, this was demonstrated only on one sampling occasion, 15 d after withdrawal.     

Migratory patterns of B lymphocytes: II. Fate of cells from central lymphoid organs in the chicken

Studies were made of the fate of ³H-nucleoside-labeled chicken bursa, thymus and bone marrow cells after intravenous injection into 8-day-old, irradiated chickens. A higher rate of proliferation of bursa cells was indicated by the fact that bursa cells incorporated more ³H-thymidine and ³H-adenosine than thymus cells, while ³H-uridine incorporation was similar for these two cell types. Homing patterns in recipient spleen tissue were similar for all three nucleoside-labeled bursa cells. Bursa cells localized in follicular and periellipsoidal areas, whereas thymus cells preferentially homed to periarteriolar sheaths. Bone marrow cells were found in all these locations. Bursa cells from chickens aged 4 weeks and older showed a greater tendency to home to the spleen than did bursa cells from 8-day-old donor chickens. Homing to other tissues appeared independent of donor age.     

Bacterial flora in the alimentary tract of chickens infected with Eimeria brunetti and in chickens immunized with Eimeria maxima and cross-infected with Eimeria brunetti

Differential bacterial counts were made on the intestinal and caecal contents of chickens after inoculation with a standard dose of 320 000 freshly sporulated oocysts of Eimeria brunetti.     

鸭群中REV感染的流行病学调查

[目的]了解网状内皮组织增生病病毒(REV)在鸭群中的感染状态.[方法]从山东省不同地区送检的病(死)鸭中,随机采集法氏囊、脾脏和肝脏等220份样品.细胞培养分离病毒,以提取的组织DNA为模板进行特异性斑点杂交、PCR和nest-PCR检测.从不同地区阳性样品中任选一个进行克隆测序、同源性比较和进化树分析.[结果]从35/39份法氏囊、54/84份脾脏和32/97份肝脏DNA样品中检出REV(121/220).其中法氏囊的检出率最高,显著高于肝脏、脾脏(P<0.01),但用细胞培养分离病毒、常规PCR、组织DNA直接点杂交检测时,均未检出REV.YN-1和BZ-1株env基因片段与美国分离的鸭源SNV株同源性高达99.8%,LQ-1株env基因片段与美国鸡源分离株的同源性为100%,均高于近几年中国鸡源分离株.[结论]在检测REV感染时,应加强对法氏囊的检测,但由于REV在感染鸭的组织中含量很低,应采用更为敏感的nest-PCR.同源性和进化树分析表明,我国鸭源REV很可能是在引进未经对REV检疫的种鸭时引入的.     

Effects of dietary inclusion of triticale,rye and wheat and xylanase supplementation on growth performance of broiler chickens and fermentation in the gastrointestinal tract

An experiment was performed over a period of 5 weeks with 576 one-day-old cockerels (Cobb 500), which were randomly divided into 6 experimental groups (12 replicate cages with 8 birds/cage). The objective of the experiment was to estimate whether different grain types (wheat, rye or triticale) and exogenous xylanase inclusion influence the performance and the gastrointestinal ecosystems of broiler chickens as regards intestinal viscosity, pH as well as the concentration of short-chain fatty acids (SCFA) and lactic acid (LA). The rye-based diets resulted in the poorest production results followed by wheat and triticale-based diets. Ileal viscosity decreased in the range: rye (140 cps), triticale (6.1 cps) and wheat (2.5 cps). Xylanase supplementation reduced ileal viscosity significantly only in birds fed with rye. The cereal type influenced the fermentation process in the broiler gastrointestinal tract more than the xylanase supplementation. The total concentration of organic acids was highest in the caeca, followed by the crop, ileum and gizzard. Lactic acid concentrations were highest in the content of the crop followed by ileum, gizzard and caeca. Propionate was only detected in caecal contents, whereas butyrate was also found in small amounts in the contents of the crop of birds from all treatments. The concentrations of acetate, butyrate and total organic acid concentration in caecal contents of chickens receiving the rye-based diets were lower than in birds fed the other cereals (P<0.001). Enzyme supplementation reduced the relative weight of the caeca in rye-fed birds (P=0.001).     

Prevalence of campylobacters and arcobacters in ducks at the abattoir

Ten duck carcasses, five from each of two different flocks, and four pairs of pooled duck caecal contents, each pair from a separate flock, were examined by a variety of techniques for arcobacters and campylobacters. Campylobacter coli, C. jejuni ssp. jejuni , C. upsaliensis, Arcobacter cryaerophilus and A. butzleri were isolated from duck caecal contents. Campylobacter coli, C. jejuni ssp. jejuni, A. cryaerophilus, A. butzleri and A. skirrowii were isolated from carcasses. The most effective methods for isolating these bacteria from carcasses involved selective enrichment in campylobacter enrichment broth, containing a cefoperazone, amphotericin, teicoplanin supplement, followed by plating onto modified charcoal cefoperazone deoxycholate agar (mCCDA), or plating onto non-selective blood agar after filtration through a 0·65 μm pore size cellulose acetate filter. In contrast, recovery from caecal contents was most effective by direct plating onto mCCDA. API test strips performed poorly, failing to identify A. skirrowii or A. butzleri (which are not included in the scheme), or even many common campylobacters. The Preston biochemical characterization scheme was more helpful, though it did not distinguish between Arcobacter species. The species of most isolates of campylobacter, identified using the Preston scheme, was confirmed by the use of SDS-PAGE of whole cell proteins and this technique was also used successfully to speciate arcobacters.     

The Effect of Rumen and Post-Rumen Feeding of Carbohydrates on the Caecal Microflora of Sheep

S ummary . When sheep were bottle-fed with solutions of glucose, sucrose or maltose, so avoiding fermentation in the rumen, there was a marked increase in the number of caecal bacteria, with a higher percentage of viable bacteria, compared with caecal counts from sheep fed conventionally on carbohydrates. Bottle-feeding also resulted in a redistribution of bacterial types, 40–46% of the flora comprising Gram positive rods and a significant increase in butyric acid and decrease in propionic acid in the caecal contents. Feeding cellulose suspensions by bottle or conventionally failed to produce significant differences in counts of cellulolytic caecal bacteria. When sucrose was infused in increasing amounts into the abomasum, Streptococcus bovis was the principal organism, isolated from faeces.     

Effects of high dietary cellulose on the large intestinal microflora and short-chain fatty acids in rats

Wistar rats fed diets containing different contents of cellulose or 5% transgalactosylated oligosaccharides (TOS) for 7 weeks were examined for faecal microflora and caecal short-chain fatty acids. High (15%) cellulose diet showed remarkable increases in concentrations of faecal bifidobacteria and caecal butyrate with a reduced concentration of propionate as compared with the other diets. TOS-fed rats showed strikingly increased concentrations of bifidobacteria and acetate. A comparison of pH values between the caecal contents and faeces suggested more fermentation of cellulose in the distal than proximal part of the large bowel of rats.     

The invasiveness of different strains of Salmonella enteritidis phage type 4 for young chickens

Five strains of Salmonella enteritidis phage type 4 (PT4) isolated in 1978, 1984 and 1988 were examined for their ability to colonise the caecum and invade the liver of day-old chickens. All strains were capable of caecal colonisation and there were no differences in their colonisation ability in this respect. In contrast there was a gradation in the ability of strains to invade the liver, with strains isolated in 1988 proving the most invasive. Absence of a 38 megadalton (Md) plasmid, which has been shown to be involved in the virulence of S. enteritidis PT4 for BALBc mice, had little effect on the ability of strains of this phage type to colonise the caecum or invade the liver of day-old chickens. These results suggest that recent isolates of PT4 may have enhanced virulence for chickens which is not necessarily associated with the carriage of a 38 Md plasmid.     

A note on lactobacilli and β-glucuronidase activity in the intestinal contents of mice

A comparison was made of caecal β-glucuronidase activity in the caecal contents of mice with or without lactobacilli as members of the normal microflora. Male mice that did not have lactobacilli as intestinal inhabitants had approximately 52% more caecal β-glucuronidase activity than their female counterparts. Colonization of male mice by lactobacilli reduced the β-glucuronidase activity to that of female mice.     

Growth and Chromatic Adaptation of Nostoc sp. Strain MAC and the Pigment Mutant R-MAC

A spontaneous, stable, pigmentation mutant of Nostoc sp. strain MAC was isolated. Under various growth conditions, this mutant, R-MAC, had similar phycoerythrin contents (relative to allophycocyanin) but significantly lower phycocyanin contents (relative to allophycocyanin) than the parent strain. In saturating white light, the mutant grew more slowly than the parent strain. In nonsaturating red light, MAC grew with a shorter generation time than the mutant; however, R-MAC grew more quickly in nonsaturating green light.

When the parental and mutant strains were grown in green light, the phycoerythrin contents, relative to allophycocyanin, were significantly higher than the phycoerythrin contents of cells grown in red light. For both strains, the relative phycocyanin contents were only slightly higher for cells grown in red light than for cells grown in green light. These changes characterize both MAC and R-MAC as belonging to chromatic adaptation group II: phycoerythrin synthesis alone photocontrolled.

A comparative analysis of the phycobilisomes, isolated from cultures of MAC and R-MAC grown in both red and green light, was performed by polyacrylamide gel electrophoresis in the presence of 8.0 molar urea or sodium dodecyl sulfate. Consistent with the assignment of MAC and R-MAC to chromatic adaptation group II, no evidence for the synthesis of red light-inducible phycocyanin subunits was found in either strain. Phycobilisomes isolated from MAC and R-MAC contained linker polypeptides with relative molecular masses of 95, 34.5, 34, 32, and 29 kilodaltons. When grown in red light, phycobilisomes of the mutant R-MAC appeared to contain a slightly higher amount of the 32-kilodalton linker polypeptide than did the phycobilisomes isolated from the parental strain under the same conditions. The 34.5-kilodalton linker polypeptide was totally absent from phycobilisomes isolated from cells of either MAC or R-MAC grown in green light.

     

Fermentation of carbohydrates and yield of microbial protein in mixed cultures of rabbitcaecal microorganisms

Fermentation pattern and yields of microbial protein were investigated in cultures of the rabbit caecal contents supplied with glucose, xylose, starch, pectin and xylan. Rabbits at the age of 4 weeks (before weaning) and 3 months were slaughtered, their caecal contents added at 1.1% to growth media and incubated anaerobically at 39°C for 18 h. Caecal microorganisms of 4‐week‐old rabbits produced no methane and caproate, less butyrate, but more propionate than microorganisms of 3‐month‐old rabbits. In both groups of rabbits, fermentation of xylose produced significantly more propionate and less butyrate than fermentation of glucose. More propionate and less acetate was formed from starch than from pectin. In caecal cultures from 4‐week‐old rabbits with pectin, the molar percentages of acetate was significantly higher and percentages of other short‐chain fatty acids (SCFA) lower than in cultures with starch or xylan. In cultures from 3‐month‐old rabbits, fermentation of pectin and xylan produced similar SCFA profiles, different from SCFA molar composition in cultures with starch. Average production of microbial protein was 129mg per lg of carbohydrate digested (range 110 to 141mg/g). Protein yields were the same on glucose and xylose, but nonsignificantly higher on starch than on pectin and xylan. It can be concluded that the characteristics of substrate affected fermentation pattern in mixed cultures of rabbit caecal microorganisms. Substrate effects on protein yields were not statistically significant, due to high variation.     

Enumeration and diversity of campylobacters and bacteriophages isolated during the rearing cycles of free-range and organic chickens

Campylobacters and Campylobacter-specific bacteriophages were isolated and enumerated during the rearing cycle of free-range (56 days) and organic chickens (73 days) at 3-day intervals from hatching until slaughter. In both flocks Campylobacter jejuni was the initial colonizer but Campylobacter coli was detected more frequently from 5 weeks of age. The diversity of the Campylobacter isolates was examined by pulsed-field gel electrophoresis of SmaI-digested genomic DNA and antimicrobial resistance typing. Bacteriophages were isolated from 51% (19 of 37 birds) of Campylobacter-positive organic birds (log10 2.5 to log10 5.7 PFU/g of cecal contents). The bacteriophages were all typical group III Campylobacter bacteriophages in terms of genomic size but could be characterized in terms of their host range and placed into five different groups. In contrast to the organic birds, anti-Campylobacter activity (bacteriocin-like) was observed in 26% (10 of 38 birds) of Campylobacter-positive free-range birds, and only one bacteriophage was isolated. Appearance of either bacteriophages or anti-Campylobacter activity was associated with changes in the levels of colonization and the predominant genotypes and species isolated. The frequency and potential influence of naturally occurring bacteriophages and/or inhibitory substances on the diversity and fluctuations of populations of campylobacters have not previously been reported in either free-range or organic chickens.     

Microorganisms Responsible for Controlling the Populations of Escherichia coli and Enterococcus and the Consistency of Cecal Contents in the Chicken

A study was made to clarify what kinds of intestinal organisms might be responsible for controlling the populations of Escherichia coli and Streptococcus faecalis var. liquefaciens in the cecum and the consistency of the cecal contents of chickens. Germ-free chickens were inoculated orally with various mixtures of bacterial cultures alone or in combination, different dilutions of the cecal contents of chickens, different dilutions of the cecal contents treated by heating or with chloroform, the supernatant of diluted cecal contents, and dilutions of human feces. Factors controlling the E. coli population, enterococcal population, and consistency of the cecal contents were shown to be independent of one another. The ecosystem controlling the E. coli or enterococcal population was more complex than that controlling the consistency of the cecal contents. The former was composed of anaerobic and facultatively anaerobic bacteria isolated and heat- or chloroform-resistant organisms, and the latter of heat- or chloroform-resistant organisms alone, which were inferred not to be prevailing in the cecal contents of chickens. Discussion is made on ecological systems controlling the intestinal flora.     

Effect of substrate and feed antibiotics on in vitro production of volatile fatty acids and methane in caecal contents of chickens

An attempt was done to identify some factors influencing the caecal fermentation pattern in poultry. Experiments were conducted to study effects of carbohydrate substrates (feed components and supplements) and antibiotics on the formation of volatile fatty acids (VFA) and methane in in vitro incubations of the caecal contents of 7-week-old chickens. Stoichiometry of fermentation differed in cultures with different carbohydrates. Fermentation pattern characterized by high propionate and low acetate production was found in cultures with lactose (0.447 and 0.376 mol/1 mol of VFA produced, respectively) and, to a lesser extent, also in cultures with raffinose. Acetate was the predominant metabolite of starch, pectin and xylan (0.727, 0.773 and 0.685 mol/1 mol of VFA produced, respectively). Fermentation of inulin resulted in high proportion of butyrate, 0.221 mol/1 mol of VFA. Other polysaccharides produced only 0.060–0.111 mol of butyrate per 1 mol of VFA. Oligosaccharides (lactose, raffinose) were fermented more rapidly than polysaccharides. Fermentation of inulin yielded more VFA than fermentation of starch, pectin and xylan. No production of VFA from carboxymethylcellulose was observed. On average, 11 mols of VFA were produced per mol of methane. Lasalocid significantly increased molar proportion of propionate, which is potentially beneficial from the point of view of salmonellae control. The magnitude of improvement, however, was small. Other feed antibiotics tested (avoparcin, bacitracin, lincomycin, spiramycin, tylosin, virginiamycin) produced only non-significant or marginal fermentation shifts. Formation of valerate, isoacids and methane was not significantly influenced by the substrate or by antibiotic treatment.     

Caecal microbiota could effectively increase chicken growth performance by regulating fat metabolism

It has been established that gut microbiota influences chicken growth performance and fat metabolism. However, whether gut microbiota affects chicken growth performance by regulating fat metabolism remains unclear. Therefore, seven-week-old chickens with high or low body weight were used in the present study. There were significant differences in body weight, breast and leg muscle indices, and cross-sectional area of muscle cells, suggesting different growth performance. The relative abundance of gut microbiota in the caecal contents at the genus level was compared by 16S rRNA gene sequencing. The results of LEfSe indicated that high body weight chickens contained Microbacterium and Sphingomonas more abundantly (P < 0.05). In contrast, low body weight chickens contained Slackia more abundantly (P < 0.05). The results of H & E, qPCR, IHC, WB and blood analysis suggested significantly different fat metabolism level in serum, liver, abdominal adipose, breast and leg muscles between high and low body weight chickens. Spearman correlation analysis revealed that fat metabolism positively correlated with the relative abundance of Microbacterium and Sphingomonas while negatively correlated with the abundance of Slackia. Furthermore, faecal microbiota transplantation was performed, which verified that transferring faecal microbiota from adult chickens with high body weight into one-day-old chickens improved growth performance and fat metabolism in liver by remodelling the gut microbiota. Overall, these results suggested that gut microbiota could affect chicken growth performance by regulating fat metabolism.     

Functional Similarities between Pigeon ‘Milk’ and Mammalian Milk: Induction of Immune Gene Expression and Modification of the Microbiota

Pigeon ‘milk’ and mammalian milk have functional similarities in terms of nutritional benefit and delivery of immunoglobulins to the young. Mammalian milk has been clearly shown to aid in the development of the immune system and microbiota of the young, but similar effects have not yet been attributed to pigeon ‘milk’. Therefore, using a chicken model, we investigated the effect of pigeon ‘milk’ on immune gene expression in the Gut Associated Lymphoid Tissue (GALT) and on the composition of the caecal microbiota. Chickens fed pigeon ‘milk’ had a faster rate of growth and a better feed conversion ratio than control chickens. There was significantly enhanced expression of immune-related gene pathways and interferon-stimulated genes in the GALT of pigeon ‘milk’-fed chickens. These pathways include the innate immune response, regulation of cytokine production and regulation of B cell activation and proliferation. The caecal microbiota of pigeon ‘milk’-fed chickens was significantly more diverse than control chickens, and appears to be affected by prebiotics in pigeon ‘milk’, as well as being directly seeded by bacteria present in pigeon ‘milk’. Our results demonstrate that pigeon ‘milk’ has further modes of action which make it functionally similar to mammalian milk. We hypothesise that pigeon ‘lactation’ and mammalian lactation evolved independently but resulted in similarly functional products.     

beta-Aspartylglycine, a substance unique to caecal contents of germ-free and antibiotic-treated mice.

The caecal supernatants from germ-free, antibiotic-treated and control mice were compared with respect to their content of low-molecular-weight substances (less than 3500 mol. wt.). The supernatants contained about the same amount of free amino acids. After acid hydrolysis, the caecal supernatants of germ-free and antibiotic-treated mice showed a 2.9-fold increase in free amino acids, whereas a similar treatment of the supernatant from control mice resulted in a 2.6-fold increase. By gel filtration on Sephadex G-25, and high-voltage paper electrophoresis at pH 3.5 of the fractions eluted after the void volume, it was found that the caecal supernatants of germ-free and antibiotic-treated mice contained a substance more acidic than aspartic acid. Preparative high-voltage electrophoresis, dansylation, amino acid analysis and a specific colour reaction showed the substance to be beta-aspartylglycine. After a minimal 36 h of treatment with neomycin and bacitracin, a high concentration of beta-aspartylglycine was found, and no enterococci and aerobic Gram-negative rods could be cultured from the caecal contents. The possibility that in one mouse the appearance of beta-aspartylglycine was related to a decrease in Gram-negative rods was ruled out by selective elimination of aerobic Gram-negative rods by using polymyxin B. This suggests that other bacteria concomitantly eliminated with the enterococci and aerobic Gram-negative rods, directly or indirectly, could play a role in the accumulation of beta-aspartylglycine.     

Intestinal accumulation of urea in germ-free animals--a factor in caecal enlargement

To examine the connection between caecal size and urea concentration in the caecal contents urease inhibition was tested in conventional animals and urea and urease were administered to germ-free rats and mice. Administration of alloxan and barbituric acid and immunization with urease led to slightly larger caeca in conventional animals. Neomycin treatment caused a clear enlargement of the caecum. In germ-free animals urease administration led to a reduction in the caecal size, whereas urea in the drinking water caused enlargement. The urea concentration and the urease activity in the caecal contents correlated well with the caecal weights.     

Comparison Between a Live,Attenuated Anticoccidial Vaccine and an Anticoccidial Ionophore,on Performance of Broilers Raised with or without a Growth Promoter,in an Initially Eimeria-Free Environment

An experiment was carried out to study the effects of vaccination with Paracox®, a live, attenuated vaccine against avian coccidiosis, on broilers isolated from extraneous Eimeria parasites. The study involved 3200 broiler chickens raised in floor pens similar to commercial conditions, but in an initially Eimeria-free environment. Forty percent of the chickens were vaccinated at 3 days of age and given either a basal unmedicated feed or a feed supplemented with the feed antibiotic virginiamycin. Unvaccinated birds were given either the basal feed or feed supplemented either with virginiamycin or the anticoccidial ionophore narasin. At slaughter at 36 days of age vaccinated birds had a lower live weight than non-vaccinated birds. The difference was 4.6% in unmedicated, and 6.0% in virginiamycin medicated chickens. Feed conversion ratio at slaughter was 2.5% higher for unmedicated vaccinated birds, and 1.3% higher for virginiamycin medicated vaccinated birds, compared to respective non-vaccinated groups. There was no significant difference in overall performance of unvaccinated birds given narasin as compared to virginiamycin. At 10 days post vaccination vaccinated birds had a higher number of Clostridium perfringens in the caeca, but there was no difference thereafter. Throughout the experiment, caecal clostridial counts were considerably higher in vaccinated unmedicated birds than in unvaccinated birds given narasin. The number of oocysts shed in the vaccinated groups was very low, but during a subsequent challenge with E. maxima and E. tenella the birds’ immunity was found to be satisfactory.