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PubMed2003

Severe acute respiratory syndrome vaccine development: experiences of vaccination against avian infectious bronchitis coronavirus.

Vaccines against infectious bronchitis of chickens (Gallus gallus domesticus) have arguably been the most successful, and certainly the most widely used, of vaccines for diseases caused by coronaviruses, the others being against bovine, canine, feline and porcine coronaviruses. Infectious bronchitis virus (IBV), together with the genetically related coronaviruses of turkey (Meleagris gallopovo) and ring-necked pheasant (Phasianus colchicus), is a group 3 coronavirus, severe acute respiratory syndrome (SARS) coronavirus being tentatively in group 4, the other known mammalian coronaviruses being in groups 1 and 2. IBV replicates not only in respiratory tissues (including the nose, trachea, lungs and airsacs, causing respiratory disease), but also in the kidney (associated with minor or major nephritis), oviduct, and in many parts of the alimentary tract--the oesophagus, proventriculus, duodenum, jejunum, bursa of Fabricius, caecal tonsils (near the distal end of the tract), rectum and cloaca (the common opening for release of eggs and faeces), usually without clinical effects. The virus can persist, being re-excreted at the onset of egg laying (4 to 5 months of age), believed to be a consequence of the stress of coming into lay. Genetic lines of chickens differ in the extent to which IBV causes mortality in chicks, and in respect of clearance of the virus after the acute phase. Live attenuated (by passage in chicken embryonated eggs) IBV strains were introduced as vaccines in the 1950s, followed a couple of decades later by inactivated vaccines for boosting protection in egg-laying birds. Live vaccines are usually applied to meat-type chickens at 1 day of age. In experimental situations this can result in sterile immunity when challenged by virulent homologous virus. Although 100% of chickens may be protected (against clinical signs and loss of ciliary activity in trachea), sometimes 10% of vaccinated chicks do not respond with a protective immune response. Protection is short lived, the start of the decline being apparent 9 weeks after vaccination with vaccines based on highly attenuated strains. IBV exists as scores of serotypes (defined by the neutralization test), cross-protection often being poor. Consequently, chickens may be re-vaccinated, with the same or another serotype, two or three weeks later. Single applications of inactivated virus has generally led to protection of <50% of chickens. Two applications have led to 90 to 100% protection in some reports, but remaining below 50% in others. In practice in the field, inactivated vaccines are used in laying birds that have previously been primed with two or three live attenuated virus vaccinations. This increases protection of the laying birds against egg production losses and induces a sustained level of serum antibody, which is passed to progeny. The large spike glycoprotein (S) comprises a carboxy-terminal S2 subunit (approximately 625 amino acid residues), which anchors S in the virus envelope, and an amino-terminal S1 subunit (approximately 520 residues), believed to largely form the distal bulbous part of S. The S1 subunit (purified from IBV virus, expressed using baculovirus or expressed in birds from a fowlpoxvirus vector) induced virus neutralizing antibody. Although protective immune responses were induced, multiple inoculations were required and the percentage of protected chickens was too low (<50%) for commercial application. Remarkably, expression of S1 in birds using a non-pathogenic fowl adenovirus vector induced protection in 90% and 100% of chickens in two experiments. Differences of as little as 5% between the S1 sequences can result in poor cross-protection. Differences in S1 of 2 to 3% (10 to 15 amino acids) can change serotype, suggesting that a small number of epitopes are immunodominant with respect to neutralizing antibody. Initial studies of the role of the IBV nucleocapsid protein (N) in immunity suggested that immunization with bacterially expressed N, while not inducing protection directly, improved the induction of protection by a subsequent inoculation with inactivated IBV. In another study, two intramuscular immunizations of a plasmid expressing N induced protective immunity. The basis of immunity to IBV is not well understood. Serum antibody levels do not correlate with protection, although local antibody is believed to play a role. Adoptive transfer of IBV-infection-induced alphabeta T cells bearing CD8 antigen protected chicks from challenge infection. In conclusion, live attenuated IBV vaccines induce good, although short-lived, protection against homologous challenge, although a minority of individuals may respond poorly. Inactivated IBV vaccines are insufficiently efficacious when applied only once and in the absence of priming by live vaccine. Two applications of inactivated IBV are much more efficacious, although this is not a commercially viable proposition in the poultry industry. However, the cost and logistics of multiple application of a SARS inactivated vaccine would be more acceptable for the protection of human populations, especially if limited to targeted groups (e.g. health care workers and high-risk contacts). Application of a SARS vaccine is perhaps best limited to a minimal number of targeted individuals who can be monitored, as some vaccinated persons might, if infected by SARS coronavirus, become asymptomatic excretors of virus, thereby posing a risk to non-vaccinated people. Looking further into the future, the high efficacy of the fowl adenovirus vector expressing the IBV S1 subunit provides optimism for a live SARS vaccine, if that were deemed to be necessary, with the possibility of including the N protein gene.

Animals↗
PubMed2004

Occurrence of avian leukosis virus subgroup J in commercial layer flocks in China.

Mortality from myeloid leukosis was observed in commercial layers from 12 farms in northern China. Affected chickens were extremely thin and dehydrated, bleeding occurred in feather follicles and claws, combs were pale and anaemic, phalanges were swollen, and many yellowish-white tumours were seen on the visceral surface of the sternum. Focal tumour cells, with spherical eosinophilic granules in the cytoplasm, were found in the liver, spleen, kidney, ovary, oviduct, lung, bone marrow, proventriculus and gut by histopathological examination. Immunohistochemical studies with a monoclonal antibody to gp85 of avian leukosis virus subgroup J (ALV-J) revealed antigen in all organs examined. Polymerase chain reaction tests using a pair of ALV-J-specific primers H5/H7 (Smith et al., 1998) produced a 545 basepair fragment. The sequence of the Polymerase chain reaction product was compared with that of the ALV-J HPRS-103 prototype strain. The identity of nucleotides and predicted amino acids was 97.4% and 96.1%, respectively. On this basis the disease in the egg-type chickens was diagnosed as an ALV-J infection. This is the first report of field cases of myeloid leukosis caused by ALV-J in commercial egg-type chickens.

Animals↗
PubMed2005

A disease complex associated with pigeon circovirus infection, young pigeon disease syndrome.

In order to collect more convincing data on the aetiological agent of young pigeon disease syndrome (YPDS), a comprehensive study was performed on pigeons in German lofts with or without outbreaks of YPDS. The investigations included examination of histories, clinical signs and pathology, as well as parasitological and microbiological analysis. Pigeons in their 4th to 12th week of life exhibited clinical signs at higher frequency and with greater severity than pigeons of other ages. Greenish liquid in the crop, proventriculus and ventriculus, and yellow fluid in the small intestine were seen more often in YPDS-affected pigeons. Escherichia coli and Klebsiella pneumoniae were isolated more frequently from these birds. Depletion of splenic and bursal lymphocytes was only seen in pigeons with YPDS. Inclusion bodies were present in various organs, especially the bursa of Fabricius. The genome of pigeon circovirus was detected in lymphoid tissues from all pigeons with YPDS. The results of this study indicate that YPDS is a multifactorial disease in which pigeon circovirus might be a crucial factor, possibly by inducing immunosuppression in infected birds.

Animals↗
PubMed2006

Acute poisoning of silver gulls (Larus novaehollandiae) following urea fertilizer spillage.

Two episodes of accidental urea toxicosis are described in wild silver gulls (Larus novaehollandiae) following spillage of fertilizer grade urea at a commercial shipping facility near Perth, Western Australia. In both cases, urea spillage had been seen to contaminate freshwater wash-down pools on the wharves where ships were being unloaded and gulls were seen to be drinking and washing in the pools nearby the spillages. Affected birds were found moribund or dead. Necropsy and histopathological findings were non-specific and consisted of mild to moderate congestion of visceral organs and brain. Analysis of a water sample collected during Case 1 revealed a very high urea concentration of 4.124 mol/l (pH 5.5), and fluid from the proventriculus of two birds had urea concentrations of 382 and 308 mmol/l, respectively. Nine birds were examined during the second episode (Case 2) and, from heparinized heart blood samples collected (n = 5), the mean plasma urea (288 +/- 92.0 mmol/l), ammonia (43.9 +/- 34.2 mmol/l) and uric acid (7.45 +/- 1.99 mmol/l) concentrations were markedly elevated above the reference ranges for all bird species. Proventricular contents (n = 7) similarly contained high concentrations of urea (394 +/- 203 mmol/l) and ammonia (9.3 +/- 15 mmol/l). The probable mechanisms of urea and ammonia toxicity in these birds are discussed.

Animals↗
PubMed1983

Mn ions pass through calcium channels. A possible explanation.

The divalent transition-metal cations Fe, Co, and Ni were used to test the hypothesis that Mn ions pass through calcium channels because Mn ions have a relatively low energy of hydration. The test ions were applied to the bath and comparisons were made of their effects on Ca or Mn spikes elicited from myoepithelial cells of the proventriculus of the polychaete worm Syllis spongiphila. Control experiments showed that (a) results obtained using deoxygenated solutions (required to stabilize Fe2+ ions) could be compared with those using solutions containing oxygen, and (b) the test cations did not measurably affect the electrical coupling between cells. Ca spikes were reversibly abolished by the test cations in the order of effectiveness: Fe (16.1 mM +/- 1.0, SE; n = 15) = Co (14.6 mM +/- 0.8; n = 27) less than Ni (8.3 mM +/- 0.7; n = 16). The test cations diminished Mn spikes by decreasing maximum rates of rise (Fe = Co less than Ni) and overshoot amplitudes (Fe less than Co less than Ni). The test cations also increased the current intensity required for Ca (Fe = Co less than Ni) or Mn spike initiation (Fe less than Co less than Ni). Since the energies of hydration of Fe, Co, and Ni increase stepwise from that of Mn, and the effectiveness of these ions in diminishing Ca and Mn spikes increased in the order Fe less than or equal to Co less than Ni, these data support the hypothesis that Mn ions pass through Ca channels because they shed waters of hydration relatively easily. An additional observation was that, at below-blocking concentrations, the test cations caused decreased duration of Mn spikes and increased duration of Ca spikes.

Action Potentials↗
PubMed2004

Transmission of Yersinia pestis from an infectious biofilm in the flea vector.

Transmission of plague by fleas depends on infection of the proventricular valve in the insect's foregut by a dense aggregate of Yersinia pestis. Proventricular infection requires the Y. pestis hemin storage (hms) genes; here, we show that the hms genes are also required to produce an extracellular matrix and a biofilm in vitro, supporting the hypothesis that a transmissible infection in the flea depends on the development of a biofilm on the hydrophobic, acellular surface of spines that line the interior of the proventriculus. The development of biofilm and proventricular infection did not depend on the 3 Y. pestis quorum-sensing systems. The extracellular matrix enveloping the Y. pestis biofilm in the flea appeared to incorporate components from the flea's blood meal, and bacteria released from the biofilm were more resistant to human polymorphonuclear leukocytes than were in vitro-grown Y. pestis. Enabling arthropod-borne transmission represents a novel function of a bacterial biofilm.

Animals↗
PubMed2005

Digestive organ sizes and enzyme activities of refueling western sandpipers (Calidris mauri): contrasting effects of season and age.

We examined seasonal and age-related variation in digestive organ sizes and enzyme activities in female western sandpipers (Calidris mauri) refueling at a coastal stopover site in southern British Columbia. Adult sandpipers exhibited seasonal variation in pancreatic and intestinal enzyme activities but not in digestive system or organ sizes. Spring migrants had 22% higher total and 67% higher standardized pancreatic lipase activities but 37% lower total pancreatic amylase activity than fall migrants, which suggests that the spring diet was enriched with lipids but low in glycogen. Spring migrants also had 47% higher total intestinal maltase activity as well as 56% higher standardized maltase and 13% higher standardized aminopeptidase-N activities. Spring migrants had higher total enzymic capacity than fall migrants, due primarily to higher total lipase and maltase activities. During fall migration, the juvenile's digestive system was 10% larger than the adult's, and it was composed differently: juveniles had a 16% larger small intestine but a 27% smaller proventriculus. The juvenile's larger digestive system was associated with lower total enzymic capacity than the adult's due to 20% lower total chitinase and 23% lower total lipase activities. These results suggest that juvenile western sandpipers may process food differently from adults and/or have a lower-quality diet.

Age Factors↗
PubMed1997

The CRE-binding protein dCREB-A is required for Drosophila embryonic development.

We have previously described the cloning of a cyclic AMP response-element (CRE)-binding protein, dCREB-A, in Drosophila melanogaster that is similar to the mammalian CRE-binding protein CREB. dCREB-A is a member of the bZIP family of transcription factors, shows specific binding to the (CRE), and can activate transcription in cell culture. In this report, we describe the gene structure for dCREB-A, protein expression patterns throughout development and the necessary role for this gene in embryogenesis. The 4.5-kb transcript is encoded in six exons that are distributed over 21 kb of DNA. There are seven start sites and no TATA consensus sequences upstream. The dCREB-A protein is expressed in the nuclei of the embryonic salivary gland, proventriculus and stomadeum. Late in embryogenesis, tracheal cell nuclei and specific nuclei within the segments show staining with anti-dCREB-A antibodies. In adult female ovaries, dCREB-A is expressed in the stage 9 through stage 11 follicle cell nuclei. Null mutations of the dCREB-A gene give rise to animals that no longer express dCREB-A protein and die late in embryogenesis before or at hatching. The absolute requirement of dCREB-A for embryogenesis demonstrates a nonredundant function for a CRE-binding protein that will be useful in studying the role of specific signal transduction cascades in development.

Animals↗
PubMed2005

Expression of the UDP-GalNAc: polypeptide N-acetylgalactosaminyltransferase family is spatially and temporally regulated during Drosophila development.

The UDP-GalNAc : polypeptide N-acetylgalactosaminyltransferase (ppGaNTase or ppGalNAcT or pgant) enzyme family is responsible for the first committed step in the synthesis of mucin-type O-glycans on protein substrates. Previous work from our group has demonstrated both sequence and functional conservation between members of this family in mammals and the fruit fly, Drosophila melanogaster. One member of this family in Drosophila has been shown to be essential for viability and development. In an effort to understand the developmental stages and processes in which O-glycosylation is involved, we have determined the expression pattern of each functional family member as well as putative isoforms during Drosophila development. Our studies indicate that isoforms are expressed in discrete spatial and temporal fashions during development, with some isoforms being found uniquely in restricted areas of the developing embryo (brain, trachea, pharynx, esophagus, proventriculus, and amnioserosa), whereas others are found in multiple regions and overlap with the expression of other isoforms (salivary glands, posterior midgut, anterior midgut, and the fore-/hindgut) during embryogenesis. Additionally, we examined expression patterns in imaginal discs from third instar larvae, which will become the adult structures. Most isoforms are also expressed in the imaginal discs, with some showing unique transcript localization and spatial regulatory control. Thus, this report provides insight into the specific regions during Drosophila development that may require O-linked glycosylation in vivo as well as which isoforms may act cooperatively in certain tissues and which may be uniquely responsible for glycosylation in others.

Animals↗
PubMed1991

Identification and distribution of tropomyosin isoforms in chicken digestive canal.

Two-dimensional gel electrophoresis of eight digestive organ extracts from 60-day-old chicks was performed. Judging from the similarity of their protein maps, the organs were classified into the following four types: 1) esophagus type, 2) proventriculus type, 3) gizzard type, and 4) intestine type. In four representative organs of these types, the distribution of tropomyosin isoforms was examined, and four high- and five low-Mr-type isoforms in addition to alpha and beta isoforms were detected in the embryonic organs. In the adult organs, however, there were three high- and four low-Mr-type isoforms, which were restricted to the mucous membrane, in addition to alpha and beta isoforms. Immunoblot analysis indicated that the high- and low-Mr-type isoforms in the embryo corresponded with those in the adult mucous membrane, but differences in the number and amount of the isoforms were found between the embryo and the adult mucous membrane.

Animals↗
PubMed1998

Stunting syndrome in broilers: effect of stunting syndrome inoculum obtained from stunting syndrome affected broilers, on broilers, leghorns and turkey poults.

Responses to stunting syndrome (SS) infective material obtained from affected broilers and administered per os were monitored for 3 wk in a fast-growing commercial broiler population, in slow-growing Leghorn chicks, and in turkey poults. At 2 and 3 wk, the size of the gastrointestinal tract (GIT) segments, the pH of the GIT contents, and the activities of digestive enzymes in the intestinal contents and of disaccharidases on the jejunum mucosae were determined. Inoculation affected the genetic stocks differently. In broiler chicks, growth and feed utilization were markedly reduced. In contrast, inoculation of Leghorns was accompanied by improved feed intake and growth rate. Performance of poults was affected only slightly, albeit significantly. The effect of inoculation on the pH of crop and intestinal contents in Leghorn chicks was opposite to that found in broiler chicks, i.e., a significant increase in the crop and small intestinal pH in the former vs a significant decrease in inoculated broilers. Although inoculation of the broiler chicks did not affect the pH in the proventriculus, in Leghorn chicks it was reduced by 25%. In poults, inoculation did not significantly affect GIT contents pH. The GIT segments were markedly enlarged in broiler chicks, whereas in Leghorn chicks the opposite trend was observed; namely, intestinal segment weights were significantly reduced. In poults, inoculation caused a reduction in the intestinal segments and gizzard weight at 3 wk. During this same period, the liver and pancreas relative weights were dramatically increased in broiler chicks. A higher relative heart weight at 2 wk was observed in broilers and poults; this trend persisted to Week 3 in poults but not in broiler chicks. In broiler chicks, a nonsignificant reduction was observed for all enzymes assayed at 3 wk and for chymotrypsin at 2 wk. In Leghorn chicks, inoculation was accompanied by a marked and significant increase in the activity of chymotrypsin during both periods. In poults, inoculation caused a marked increase in the activities of amylase during Week 2 and 3, and trypsin at 3 wk. Maltase and saccharase activities in the jejunum of broiler chicks were slightly depressed a t 2 and 3 wk, the depression being significant at 2 wk for maltase and at 3 wk for saccharase. In the Leghorn chicks, inoculation caused a twofold increase in the activities of both enzymes. As in Leghorns, inoculation of poults with SS infective material caused a marked increase in the activities of the disaccharidases. The different responses to SS inoculation in the different genetic stocks are discussed.

Animals↗
PubMed1999

The effects of delayed access to feed and water on the physical and functional development of the digestive system of young turkeys.

Three experiments were conducted with turkeys to determine the influence of delayed access to feed and water on the development of the digestive system. In all experiments, poults were randomly assigned to three placement times, 6, 30, and 54 h posthatch. Experiments 1, 2, and 3 were terminated when poults were 10, 28, and 14 d old, respectively. In Experiment 1, six poults per treatment were sampled on Days 1, 2, 3, 4, 5, 6, 8, and 10. In Experiment 2, 12 poults per treatment were sampled on Days 1, 2, 3, 4, 5, 10, 15, and 28. The objective of Experiment 3 was to determine the effect of delayed placement on dietary MEn. Delaying access to feed and water for 54 h adversely affected BW through 10, 28, and 14 d of age in Experiments 1, 2, and 3, respectively (P < or = 0.01). Delayed access to feed and water for 54 h decreased the absolute weights of the small intestine and pancreas and reduced lengths of the small intestine through 5 d posthatch (P < or = 0.05). The relative weights of the small intestine and proventriculus were reduced by delayed access to nourishment through 4 d posthatch. Poults placed on feed at 54 h posthatch had decreased pancreatic amylase activity (P < or = 0.05) at 3 and 4 d, and trypsin activities were depressed at 3 d posthatch (P < or = 0.05). In Experiment 3, dietary MEn value determined at 4 d of age with poults placed 54 h posthatch was less (P < or = 0.07) than the MEn value obtained with poults placed at 6 h posthatch. A 54-h delay in access to feed and water generally delayed development of the digestive system, impaired nutrient utilization, and reduced BW.

Animals↗
PubMed2000

The toxicity of purified fumonisin B1 in broiler chicks.

An investigation of the toxicity of fumonisin B1 (FB1), a toxic metabolite of Fusarium moniliforme, in broiler chicks was conducted. Purified FB1 (98.1% pure) was incorporated into the diets of broiler chicks at 0, 20, 40, and 80 mg/kg, and fed to chicks from 0 to 21 d of age. Dietary FB1, at concentrations of 80 mg/kg or less, did not adversely affect body weight, feed efficiency, or water consumption of broiler chicks. The relative weights of the liver, spleen, kidney, proventriculus, and bursa of Fabricius were also unaffected (P < 0.05) by any dietary concentration of FB1 compared with the control (0 mg/kg) group. Total liver lipids of chicks fed 40 or 80 mg FB1/kg were significantly lower than those of the chicks fed either 0 or 20 mg FB1/kg of feed. Liver sphinganine concentration and the sphinganine:sphingosine ratio were increased significantly in all treated groups. Chicks fed dietary FB1 at 80 mg/kg had significantly higher serum glutamate oxaloacetate aminotransaminase:aspartate aminotransferase ratios and levels of free sphinganine in the serum. The results of this investigation agree with the results previously described, in which FB1 was supplied to diets from the use of F. moniliforme-contaminated grain; therefore, the use of such material as the source of the mycotoxin in animal feeding studies is appropriate.

Alanine Transaminase↗
PubMed2000

Colonization of the intestinal tract by Clostridium perfringens and fecal shedding in diet-stressed and unstressed broiler chickens.

Commercial broiler chicks were given a three-strain composite of bacitracin-resistant Clostridium perfringens by oral gavage and were sampled periodically to determine the dynamics of C. perfringens colonization of the intestinal tract of broiler chickens and fecal shedding. After gavage, the chicks were divided into two groups and placed in isolators, one group received a traditional corn-based diet, and the other group received the same diet supplemented with 50% rye to place the birds under dietary stress. The numbers of bacitracin-resistant C. perfringens in various parts of the intestinal tract, liver, and feces were determined using a selective plating medium containing bacitracin. In chickens on the corn-based or 50% rye diet, C. perfringens was isolated infrequently from the various parts of the intestinal tract, liver, or fecal droppings during the first 36 h following the last gavage. For the 24 chickens on each of the two diets that were sampled from 2 to 21 d after gavage, C. perfringens was recovered more frequently from the crop, proventriculus, duodenum, jejunum, ileum, ceca, and feces, but not the gizzard, of birds on the 50% rye diet as compared to those on the corn-based diet. From 2 to 21 d, the intestinal numbers of C. perfringens in contaminated birds on the corn-based diet were < or =log10 6.2 and did not increase in any portion of the intestinal tract. Numbers of C. perfringens during this time period increased 3.3 to 4.9 log factors in the ileum, ceca, and feces of birds on the 50% rye diet to as high as log10 7.1 to 7.9 at 21 d. This study confirms that addition of rye to the diet of chickens can increase the numbers of C. perfringens in the ceca of broiler chickens and extends these findings to demonstrate increases in the numbers and frequency of recovery of C. perfringens in other parts of the intestinal tract.

Animal Feed↗
PubMed2002

Chronic effects of fumonisin B1 in broilers and turkeys fed dietary treatments to market age.

Floor pen studies were conducted with 270 broiler chicks and 144 turkey poults, all 1 wk old, to evaluate the chronic effects of fumonisin B1 (FB1). A completely randomized design was used in both studies with six pen replicates of 15 chicks or eight pen replicates of six poults assigned to each of three dietary treatments from Weeks 1 to 7 (broilers) or to Week 14 (turkeys). Fusarium moniliforme (M-1325) culture material was added to a typical corn-soybean basal diet to supply 0, 25, or 50 mg FB1/kg diet. Feed intake, body weight gain, and feed conversion of chicks were not affected (P > 0.05) by FB1. Turkeys fed 50 mg FB1/kg had significantly (P < 0.05) lower feed intake than the controls. Compared with controls, chicks and turkeys fed FB1 diets had significantly higher liver sphinganine to sphingosine ratios (P < 0.05). Relative organ weights of chicks were not affected (P > 0.05) by FB1, other than those chicks fed 25 mg FB1/kg, which had lower (P < 0.05) relative proventriculus weights than the chicks fed 0 or 50 mg FB1/kg. Broilers fed 50 mg FB1/kg had decreased serum calcium and increased serum chloride when compared to broilers fed 0 or 25 mg FB1/kg. Hematology was not affected (P > 0.05) by dietary FB1. No lesions were present in any organ examined microscopically. Results indicate that 50 mg FB1/kg diet is detrimental to turkeys but is not toxic to broilers fed to market age.

Animal Feed↗
PubMed2003

Free diet selection by broilers as influenced by dietary macronutrient ratio and corticosterone supplementation. 1. Diet selection, organ weights, and plasma metabolites.

Male broiler chickens (aged 21 d) were allowed to chose freely for 14 d between three diets in which only one specific macronutrient (protein, lipid, or carbohydrate) was isocalorically substituted for one other macronutrient, but otherwise (nearly) isocaloric and composed of the same ingredients. The three diets were low protein (LowCP; 15.81% CP; 6.56% lipid; 50.78% carbohydrate), low lipid (LowL; 19.63% CP; 3.01% lipid; 51.12% carbohydrate), and low carbohydrate (LowCHO; 19.50% CP; 7.72% lipid; 44.00% carbohydrate). The chickens either received 0, 30, or 45 mg of corticosterone (CORT) per kg diet. As a percentage of their total intake, unsupplemented chickens consumed 24.0, 71.4, and 4.6% of the LowCP, LowL, and LowCHO diets, respectively, giving a total CP, L, and CHO intake of 282, 61, and 765 g, respectively. The addition of CORT significantly changed the diet selection, as compared to the unsupplemented chickens, CORT chickens consumed a greater percentage from the LowCP (35%), less from the LowL (55%), and again more from the Low-CHO (10%) diet. On the other hand, total feed consumption, macronutrient, and ME intake were not altered significantly by CORT supplementation, probably because of the close similarity of the diets. Corticosterone-supplemented chickens manifested hyperglycemia, hyperlipidemia, and uric acidemia suggesting insulin resistance, increased lipogenesis and protein catabolism, respectively. The elevated plasma creatine kinase (CK) activities of CORT chickens are also suggestive for decreased muscle cell membrane stability. Furthermore, CORT chickens were characterized by increased proportional weights of liver, abdominal fat pad, proventriculus, and gizzard, whereas an involution of spleen and bursa was observed. In conclusion, the present results suggest that high circulating levels of CORT as in the case of stress results in metabolic alterations, which in turn, affects diet preference as a compensatory mechanism to adapt energy and nutrient metabolism.

Adipose Tissue↗
PubMed2003

Detection of Salmonella enteritidis-specific immunoglobulin A antibodies in crop samples from chickens infected with Salmonella enteritidis.

The crop (ingluvies), an organ for food storage in most avian species when the proventriculus is full, is located at the base of the esophagus. Little is known about any immunological capacity in the crop, and the current study was conducted to determine whether any antibodies to SE could be found in crop flushes taken from White Leghorn hens following infection with this organism. Surprisingly, an exceptionally strong IgA anti-SE response could be detected in the crops of hens 17 d postchallenge, and a comparison at Day 22 of crop vs. intestinal IgA anti-SE responses showed a good correlation between anti-SE antibody levels in the two regions. Histologic examination of crop tissues revealed development of lymphoid aggregates in the crop walls following challenge with SE. These results indicate that the crop may serve a role in immune protection in addition to its capacity as a food storage organ.

Animals↗
PubMed2003

Esophageal tonsil: a novel gut-associated lymphoid organ.

The esophageal tonsil of the chicken is a novel, significant element of the gut-associated lymphoid tissue (GALT). Its stable location and histological organization fulfills the meaning of the term "tonsil." The six-to-eight-isolated tonsillar units are located at the border of the esophagus and the proventriculus. The number of tonsillar units is identical with that of the esophageal folds. Each tonsillar unit consists of a crypt lined by lymphoepithelium and surrounded by dense lymphoid tissue, which is organized into T- and B-dependent regions, like peripheral lymphoid organs. The excretory ducts of the mucosal glands of the esophagus are frequently involved in the formation of the lymphoepithelium. The esophageal tonsil is anatomically located cranial to the stomach, unlike the other parts of the GALT. Therefore, it is continuously exposed to undigested environmental antigens, allergens, food, and infectious agents. To develop effective oral vaccines, the existence of the esophageal tonsil has to be taken into account.

Animals↗